2013
Urban Rainwater
Harvesting and
sustainable water
management in Sri Lanka
“Hållbar utveckling av vattenförsörjning och
hanteringen av avloppsvatten i Sri Lankas
stadsmiljö”
By : Anders Strand
Byggdesign
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 2 Abstract
The field study will investigate the importance of Rain Water Harvesting (RWH) as a water supply option. How can sustainable innovative solutions be developed to solve the water problem of Sri Lanka?
Suffering from more than 30 years of civil war and damages after being struck by the tsunami 2004, Sri Lanka faces many challenges to recover and rebuilt the country. The access to water is the most important need for a civilization´s existence. In the dry zones of the island people suffer from long drought periods with dried up wells and no natural sources for water.
However the rainfall during the monsoon, even in these areas, is more than enough to provide the water needs if properly collected, thus the run-off coefficient is more than 60%. Several projects with rain water harvesting in so called RWH systems have been implemented with success. Because these areas are not covered by the water supply net and therefore have no tap water, the people are very positive to having the RWH system.
In the wet zones and especially in the urban environment of Colombo the situation is
different. Here most of the people have treated pipe-borne tap water. The metered tap water is highly subsidized by the government which makes the cost low for the users and increases the water consumption. The citizens do not feel a responsibility to be careful with resources since the common opinion is that water is a never ending source. The majority of the households find no reasons for installing a RWH system because it´s low economic profits. Even if there is a legislation that demands all new buildings should have a RWH system not many
households have installed these systems. However the cost to deliver and treat this water is very expensive for the government and demands a lot of energy. Huge investments need to be done in both the treatment plants and the pipe-line net to meet the growing population in Colombo area. Another problem is that 40% of the households today in Colombo have no sewage connection but lead their wastewater directly or after a septic tank into the ground or the sea.
If the awareness regarding these concerns could be improved and the conditions between tap water costs and RWH be adjusted with changes in the subsidized system, a sustainable solution to the water situation in Colombo with both economic and environmental benefits could be found.
The result from the case study is a recommendation about installing RWH as a complimentary source of water for the households. And investments in RWH systems should be focused to industries, hospitals, schools, municipal buildings and other public buildings with a high water demand and with the best possibilities for optimal results.
Further the case study treats a sustainable solution to the sewage situation. It shows the Decentralized waste water treatment plant (DWWT) and its advantages.
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 3 Sammanfattning
Denna fältstudie kommer att undersöka betydelsen av regnvattenanvändning som vattenförsörjnings alternativ. Hur kan hållbara innovativa lösningar tas fram för att lösa vattenförsörjningen på Sri Lanka?
Efter lidandet av mer än 30 års inbördeskrig och efter de omfattande skadorna från tsunamin 2004, står nu Sri Lanka inför många utmaningar rörande landets återuppbyggnad. Tillgången till vatten är den viktigaste grundläggande förutsättningen för ett fungerande samhälle. I landets torra zon är det långa perioder av torka då vattenkällor sinar och inget naturligt vatten finns att tillgå. Detta trots att det under monsunen kommer tillräckligt med regn för att täcka vattenbehovet om det skulle samlas på ett optimalt sätt. Avrinningskoefficienten är här mer än 60% outnyttjat regnvatten. I ett flertal lyckade projekt har man samlat regnvatten i RWH system för senare användning. Människor i dessa områden saknar kranvatten eftersom detta område ej är täckt av vattenförsörjningsnätet. Detta gör att dessa människor har en positiv inställning till att ha RWH system..
I den våta zonen, och då speciellt i Colombos stadsmiljö som denna studie handlar om, är situationen annorlunda. Här har de flesta invånare kranvatten. Det kommunala kranvattnet är högt subventionerat av regeringen vilket gör att kostnaden är låg för användarna samt ökar vattenkonsumtionen. Invånarna känner inget ansvar för vattenresurserna eftersom den gemena uppfattningen är att det är en evig källa. Majoriteten av hushållen ser inget skäl till att
installera RWH på grund av den låga lönsamheten. Trots att det finns ett förordnande att det ska ingå ett RWH system, så följs inte detta. Saknande av uppföljningsplikt anges som orsak av vatten styrelsen. Kostnaden för att behandla och leverera vatten till invånarna är väldigt hög och är mycket energi krävande. Det finns ett behov av enorma investeringar för att rusta upp och bygga ut både vattenverken och vattennätet för att klara av att möta det växande invånarantalet i Colombo området. Ett annat problem är att 40% av hushållen i Colombo saknar avloppsanslutning. De leder sitt avloppsvatten direkt eller efter en septi-tank ut i jorden eller havet.
Om medvetenheten kring dessa frågor ökar, samt att förhållandet mellan kranvattnets kostnad och RWH justeras med ändringar i subventionerna, kunde en hållbar lösning på
vattensituationen med såväl ekonomiska som miljövinster ske
.
Resultatet av denna studie är att RWH får ses som ett komplement när det gäller
vattenförsörjningen för hushållens del. Fokus bör istället ligga på industrier, sjukhus, skolor, kommunala byggnader och andra byggnader med stora vattenbehov och med de största möjligheterna att uppnå optimalt resultat.
Studien visar också på en hållbar lösning på avloppshanteringen. Den visar DWWT och dess fördelar.
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 4 Preface
“Urban Rainwater Harvesting in Sri Lanka” is a field study granted from MFS and SIDA. The field study is written as a case study and as a final essay at Bachelor degree for Malmö
Högskola, Technique and Science, December 2012.
Introduction to people making this case study possible
A huge thanks to all people involved in this case study helping me to make it come true. Special thanks to Dr.(Ms.) Tanuja Ariyananda Executive Director at LRWHF. Her help as supervisor in field and all her help with arranging appointments with people related to the study. She also made it possible for me to participate in a four days training course in Colombo about RWH and DWWT. Huge thanks to Dr. Deblina Dwivedi and Dr. Suresh Kumar Rohilla at CSE (Centre of Science and Environment) for a interesting training course and for all useful material in the subject.
Thanks to D. Senevirathne, Chief Sociologist at NWSDB (National Water Supply & Drainage Board) for all his help with data and setting up appointments.
Special thanks to Jens Wittmis for many years of teaching and for being my Swedish supervisor during the study. Mr. Wittmis has a Master of science in Civil Engineering and I have attended his classes at Malmö Högskola. Mr. Wittmis is a very pedagogic teacher and I highly respect him for both his knowledge and helpful treatment.
Also many warm thanks to Anna Enhörning Singhateh, International Relations Officer at the International Office Malmö University for helping me with my application for the field study and all the practicalities involved.
At last but not least many thanks to all the wonderful people of Sri Lanka who always made me feel most welcome letting me into their homes and for sharing their stories. I have never met a similar friendly and unconditional attitude during my earlier travels. The warmness and kindness amongst these people are amazing.
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 5 Table of contents 1 Introduction ... 6 1.1 Background ... 6 1.2 Introduction of problem ... 7 1.3 Aim ... 7 1.4 Vision ... 8 1.5 Method ... 8 1.6 Demarcation ... 9
2 Rain Water Harvesting... 11
2.1 Introduction to LRWHF ... 12
2.2 RWH systems ... 13
2.2.1 Function ... 13
2.2.2 Maintenance ... 15
2.2.3 Usage and efficiency ... 17
2.2.4 Calculation of RWH system required ... 21
2.2.5 Costs of RWH system ... 22
2.2.6 Disadvantages with RWH ... 25
3 Economic and environmental benefits with RWH ... 27
3.1 Usages of drinking water and costs ... 27
3.2 Rain Water Policy in Sri Lanka ... 34
3.3 Cut usage of treated water with RWH ... 34
3.4 Economic benefits to the households with RWH... 37
3.5 Environmental benefits with RWH ... 37
4 Empiric study of RWH ... 40
5 Sewage in Colombo ... 43
6 Decentralized Waste Water Treatment plant... 44
6.1 Principles of DWWT ... 44
6.2 Components of the system ... 44
7 Results ... 48
7.1 RWH ... 48
7.2 DWWT ... 49
8 Conclusions and discussion ... 50
Afterword ... 52
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 6
1 Introduction
This field study is a proposal of how rain water harvesting systems in the urban areas can be a solution for a sustainable water management that will lead to economic and environmental benefits. How it can be more attractive to the Sri Lankan households and the Government.
1.1 Background
The main problem in Sri Lanka is not the scarcity of water but how the water is managed. Sri Lanka has an annual rainfall of between 2500 to 5800 mm in south west and about 1250mm in the other parts of the island. Three quarters of the country is in what is known as the Dry areas. But if you look at the amount of water coming down from the sky it is not really a dry zone compared to many European countries. It is just that all of the rain falls in the 3 months of the north-east Monsoon between October and December. And the rain often come in short dramatic bursts causing floods of water. Some places can get all their annual amount of rain in a couple of days. This is why it is so important to collect as much of this water as possible to avoid scarcity for the rest of the year. If this rainfall runoff is collected effectively on surface it will contribute during dry season from March to September. The main occupation and source of income of the farmers in these zones is farming (Shanthi de Silvaand Ariyananda, 2009 ).
Other areas like the southwest urban areas are not suffering from lack of water. But since the water is not very well managed and the consumption is increasing due to the growing
population, there are people without access to clean water. The sewer system is often flooded during the monsoon causing both health problems and environmental affects. According to studies on urban areas in Sri Lanka about 60 percent of the rainwater flows directly into the sea without benefitting the people. Building cities with mainly asphalt, cement or tiled surface coating prevents rain water to infiltrate with the ground water. This makes the ground water table to go down. Rain water harvesting can make use of this wasted water both for direct usages, ground water storages and also certify the use of drinkable pipe borne water for appropriate usages. (Fukuoka, 2011).
Several projects have been done with Rain Water Harvesting systems, from here on to be mentioned as RWH. Sri Lanka has an independent organization called Lanka RWH Forum. Lanka Rainwater Harvesting Forum, from now mentioned as LRWHF, was established at the beginning of 1996 by a small group of interested persons. They are from a range of
government and non-government institutions, including the National Water Supply and Drainage Board (NWSDB), Intermediate Technology Development Group Sri Lanka (ITSL), Community Water Supply and Sanitation Project (CWSSP), Church of Ceylon, Board of Women’s Work, NGO Water Supply and Sanitation Decade Services, Agrarian Research and Training Institute (HARTI) and the Open University. The organization has a vision which is formed as following: “Leading the nation in rain water harvesting technology, construction and utilization to sustain water needs”. (LRWHF, 2012:1).
Focus has until today been on the dry rural areas that are in the most emergent need of water. There is very few rain water harvesting system in urban areas in Sri Lanka, even though Sri Lanka have legislation since 2009 that every new building in urban and municipality area should have a rain water harvesting system. (LRWHF, 2012:2)
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 7 Sri Lanka has since 2009 legislation that every new building in urban and municipality area should have a RWH system to collect rain water (Gazette, 2009 ). Despite this there are few RWH systems in use in these areas today. In Colombo most households use drinking water coming from three different water treatment plants to cover all their needs. Even gardening water, cleaning water etc. is covered from the pipe born water. (NWSDB, 2012)
The currency being used in the study is Rs. (Sri Lanka Rupies) and the exchange rate at this time, in December 2012, was Rs.100 the same as 5,09 SEK according to FOREX.
1.2 Introduction of problem
Regarding the importance of Rain water harvesting as a water supply option, there is a need to develop sustainable innovative solutions to solve the water situation in the urban environment of Sri Lanka. Questions to be asked are the following: For what purposes can the rain water be used? What are the effects on recharging the ground water table with collecting rain water in wells and pit holes? How can the waste water management be improved? Why is RWH systems not being frequently used in the urban sector and what can be done to make the households to see the feasibility of RWH and DWWT systems? Because of today´s water for the households is being metered and up to a certain level highly subsidized they make no profit in investing in RWH. And as a result the usage of drinking water for other purposes than drinking is there for unnecessary high. Distribution and processing the drinking water cost the Sri Lankan water board a lot of money, especially since it is a non-efficient process with high electricity consumption and usage of chemicals used in the cleaning process, which needs to be imported from abroad.
In Sri Lanka only 2,5% of the country is connected to a sewage system. Some of the households have their own septic tank but many households lead their wastewater to rivers, the sea or the ground. In the Colombo area 60% have a sewage connection. 50% households without connection have their own septic tank and the rest are without any water or sewage connection and lead the wastewater through canals into the sea. How can sustainable solutions solve these problems and recycle the waste water?
1.3 Aim
The aim with the field study is to find solutions to improve the water management in Sri Lanka. Evaluate the rain water harvesting of today, the effectiveness and how it can be developed and adapted in the urban sector. What are the using areas? How much of this water can replace the tap water consumption? What are the costs involved ? Since there are not many RWH systems in use in urban areas, the aim of the study is to, if possible, help the LRWHF in their efforts and support the development of the RWH system in these areas. In the urban sector, I conduct an economic study, to see the feasibility of having RWH system, and to see what is the saving to the householders and to the water board. The urban
household´s water lines are metered, but up to a certain volume highly subsidized. If the water board could promote RWH through reduction in pipe connection fees for households, which has rain water system. And if it can be shown that the water board will be saving money in the long run if they do that, it would be easy to convince them. The water supplytoday comes from water plants which are very expensive for the water board. They are not very efficient and the cost in electricity is very high. If the household´s usage of drinking water would be
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 8 cut down there would in my opinion be both economic and environmental benefits. The loss of expenses could then be used for making the water plants more efficient.
I will also investigate how the sewage system of today can be improved with a sustainable solution.
1.4 Vision
The vision is to find a way to unite all interests; economical, political, environmental, and points of views from different professions and the people to together strive towards a sustainable city. And a personal aim is to find what I as a Building Engineer can learn from the Engineers and people and their situation in Sri Lanka. How I as a world citizen can use my education to support the Sri Lankan people´s efforts of finding sustainable solutions regarding water issues and green cities.
1.5 Method
The method being used in this field study:
Literature study of articles, case studies, books, websites and other publications on the subject
Collecting statistics about rainfall, water consumption etc.
Participating in a seminar about RWH and DWWT
Interviews and discussions from appointments
Observations and documentation in field
Empiric study
I prepared the field study by doing a pre study of articles, websites and literature in the subject. Collecting facts regarding rainfall statistics, water consumption, the infrastructure of Colombo and compare costs of today´s distribution of water to the usage of RWH systems. Mr. P.K.S. Mahanama was supposed to help me to get in contact with key-persons at the University and other people concerning the issue. He would also arrange meetings with Civil Engineers for technical guidance and support. Since Mr. Mahanama is also a Town planner he would also guide me in the aspects regarding the physical planning of the city. Unfortunately I lost contact with Mr.Mahanama when arriving Sri Lanka. Beyond his help I had already contacted the Lanka Rain Water Forum organization as an alternative and complementary source for information. In 1996 the Lanka Rain Water Forum (LRWHF) was launched with the vision of leading the nation in rain water harvesting technology, construction and
utilization to sustain water needs. The organization consists of a group of people from a range of government and non-government institutions. One of their issues is to organize workshops where rain water practitioners and national experts share and exchange information. My intention was to participate in some of their workshops and also to study a demonstration project. I also intended to collect information from the research and development at the Forum by interviewing people in and outside the organization. All this later took place in Nugegoda, just outside Colombo, where the organization is situated. I got a new supervisor for the case study in Ms.Tanuja Ariyananda, who is the Director. She provided me with all the
information I needed and arranged and set up appointments with important persons outside the Forum. Because of her help I had the possibility to meet D. Seneviratno at the Water Board and discuss the water management of Colombo. He provided me with all the figures
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 9 about the consumption and the costs for treated pipe borne water to citizens of Colombo area. Ms.Tanuja arranged for me to participate in a training course and workshop in RWH and DWWT (Decentralized Waste Water Treatment), which were held in Colombo just as I had arrived. I collected a lot of material at this training course that were later very useful for the study and I also had some practical experiences in how to calculate and design these systems. The training program was given by Dr. Suresh Kumar Rohilla, Program Director of Water management, Centre of Science and Environment and head of the Centre of Excellence in Sustainable Water management, Ministry of Urban Development, Government of India. At his help he had Dr. Deblina Dwiwedi, Program officer. Except from experienced knowledge from this course another result was many contacts with people working in these areas or from companies planning to implement RWH systems. Further appointments and visits were set up as a result of this.
My next step was to visit different social and geographic areas in Colombo that have or could have RWH systems in the future. And then I continued my trip to Galle in the south part where many RWH systems where constructed after the Tsunami because of the damages to the water supply. Photo documentation and notes where done from these visits. I interviewed both constructors and users of the systems, so that I got information from all points of views. I also did an empiric study of the RWH systems in Habarandue, which were installed after the tsunami 2004.
The methods being used in this field study have both positive effects as its limitations. The variety of the people interviewed from different social and professional fields gives a wide perspective to the problem. However it should be considered that not always their true opinions are expressed especially when there is a conflict of interest. Further Sri Lanka is not an open society regarding to the right to print or say what you want. Sometimes there might be political reasons involved. There is also a limitation with the empiric study because of the chosen area and numbers of people being interviewed. It was problem to find a similar area in Colombo because the lack of RWH systems being in use. And concerning the DWWT this is not yet a system implemented in this area.
There is also a limitation due to the size of the essay to further investigate the complexity of the economic aspects.
1.6 Demarcation
The study does not include the whole country because of the limited time for the study and scale of my essay. Previous studies from students on the subject (Clara Norell,2010) have focused on the rural areas or smaller villages so my research should focus on the situation in the urban environment. I intend to study rain water harvesting not only within basic living standards but in the complexity of a modern development city. This is because of my interest in how sustainable cities can be built in development countries with minimum impact on the environment. And to build a city with a healthy and well working water management
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 10 The study covers these different parts:
Rain water collecting systems:
Catchment areas (different types of roof material)
Conveyance systems (gutters, pipes, first flush pipes etc.)
Filter unit
Storage tank
Usages
Recharge groundwater table
Economic and Environmental benefits Sewage of Colombo:
Decentralized Waste Water Treatment plant
Principles
Components
Apart from the households I investigate differences and opportunities with public and industrial buildings. The study includes both a technical angle, with the construction and function of the rain water harvesting systems, advantages and disadvantages with them and development possibilities. Also the economical aspect is included with the costs and possible benefits.
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 11
2 Rain Water Harvesting
Rain Water Harvesting (RWH) is catching rain water when it falls and storing to use during the non rainy season. This is a method being used for more than 4000 years. Harvested rain water can be utilized for several purposes including washing, gardening, flushing and even drinking. RWH is practiced all over the world and the demand is increasing. The techniques usually found in Asia and Africa by ancient civilizations within these regions and today still serve as a major source of water supply in especially rural areas. In Sri Lanka it has been practiced throughout the history by collecting water in tanks or so called wewas. Today more than 31,000 RWH systems are in operation throughout the country most of them in rural areas. In the rural areas rain water is used for agriculture. Closed tanks made of bricks or cement which collects the rain water from the roof tops and open tanks or wells to collect the surface runoff water which can be used for both agriculture and recharge the ground water.
Photo1: Photo2: Tank collecting surface runoff.
Tank to collect rain water from roof top LRWHF,2005
LRWHF,2005
RWH in urban areas is slowly becoming popular with appropriate technology. According to studies more than 60 percent of the rain water flows back to the sea without benefitting the citizens. With RWH in these areas this wasted water could be used for toilet flushing, cleaning, laundry and gardening but because of the high polluted air it is not recommended for drinking and cooking. It would also certify the use of purified pipe borne water for appropriate usages. Except from collecting water in tanks for general use and pit holes for recharging the ground water, ponds are being used in large facilities such as factories. Today this is just in the beginning era and could be much more develop. (LRWHF, 2012:3).
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 12
2.1 Introduction to LRWHF
The Lanka Rain Water Harvesting Forum was established in 1996 by a small group concerning about the water problems of Sri Lanka. They come from a range of both government and non-government institutions including the National Water Supply and
Drainage Board, Intermediate Technology Development Group Sri Lanka, Community Water Supply and Sanitation Project, Church of Ceylon, Board of women´s work, NGO Water Supply and Decade Services, Agrarian Research and Training Institute and the Open University. The Forum consist experts, scientists, engineers, politicians and professionals working together to find sustainable solution of water management in Sri Lanka. LRWHF was officially launched 1997 by the Minister for National Housing and Public Utilities. The Forum is registered as a non-profit organization. Their mission is to solve the water problems of the nation by research and development dissemination and sharing experiences in rain water harvesting technology. The Forum´s aim is:
research and develop further techniques for RWH
promote the application for rain water to domestic purposes through information, communication, awareness raising
study efficient methods and make recommendations
promotion of RWH for gardening and domestic level agriculture
promotion RWH as a viable solution to recharge ground water table
LRWHF has a Director Board of several Professors, Engineers and Researchers. My contact person will be the Executive Director Dr. Tanuja Aryiananda.
The LRWHF has a lot of different activities like promotion, networking, research and development and practical training with workshops. My intention is to participate in one of these workshops on place in Sri Lanka. They also provide information like how to build your own RWH system or maintenance of your RWH system or Gardening with RWH and so on. The information, training and workshops are free of charge.
A long list of publications, books, brochures and papers can be found on their website. The Forum has participated in conferences all over the world concerning the issue with water problem. A long list of projects, both ongoing and completed, can be read about in their own website. The organization is very well known and has a very good reputation in the area of rain water harvesting and water supply issues. National Policy on RWH in Sri Lanka was officially implemented on September 27 of 2005. LRWHF represented the Steering
Committee for Formulating this Policy. The main objective of the Policy is to order to ensure that the City of tomorrow applies RWH broadly, by the control of water near its source, its pursuance of becoming a Green City in the future. (LRWHF, 2012:4).
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 13
2.2 RWH systems
2.2.1 Function
A typical RWH system has the following general components:
Catchment
Gutters and pipes
Filters
Storage facility
Devices to draw water out
The catchment is the area where the rain water is collected usually the roof top but also the driveway, landscape or other surfaces in runoff collecting systems. The choice of material and construction influence the efficiency of the collecting amount.
A conveyance system consisting gutters and pipes transport the water to the storage tank. It is of great importance that materials such as PVC, woods or certain metals with no
contamination risk are used for the conveyance system.
Different filters are used to filter out the debris that comes from the rooftop water and prevent them to reach the storage tank. Each filter has its function and has to be chosen by the purpose of using the rain water. There are both gutter filters and tank filters. Mesh filter is being used to prevent leaves and other big things entering the tank. First flush device is a valve that ensures the first polluted rain is being flushed out and not entering the system. Sediment discharge tap to be used on the bottom of the storage tank, to flush out the sediments settled there. If the water is being used as drinking water, which is not recommended in the urban areas, specially designed sand filters or filters made of charcoal can be used. Maintaining of these filters in good conditions is essential to provide healthy water quality.
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 14
Picture2: Filter. LRWHF,2005
Storage facility can be above, partly underground or under the ground. The storage tank can be in various shapes and in different materials. There are tanks being cylindrical, rectangular and square. Construction materials is usually reinforced concrete, Ferro cement, masonry, polyethylene (plastic) or galvanized iron sheets designed for its purpose of water usage. The size and volume can be designed after annual rainfall, catchment area, water requirements or numbers in household.
In runoff systems water can be directed to wells or pit holes for recharging the ground water table.
Devices to draw water from tank can be such as hand pumps or motorized pumps depending on usage of water and position of tank.
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 15
2.2.2 Maintenance
Maintenance is generally limited to the annual cleaning of the tank and regular inspection of
the conveyance system. This often takes place before rainfall season. A change of filters, refilling new filter media or careful cleaning will also be necessary. Maintenance typically consists of the removal of dirt, leaves and other accumulated materials. Eventual damages in the storage tanks can create major problems and should be repaired immediately. Roof should be cleaned from leaves, branches etc. at least twice a year. In the case of ground and rock catchments, additional care is required to avoid damage and contamination by people and animals, and proper fencing is also required.
A. Trimming/cutting branches from trees
near the house B. Cleaning out the gutters
C. Doing the first flush! D. Replacing the filter media.
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 16
E. Checking for cracks. F. Cleaning out the tank.
Figure 1 :Maintenance of RWH pumpkin. LRWHF,2005
To avoid mosquito entering the tank check the mosquito proof netting on a regular basis. Keep sure the tank is not letting sunlight into the water because of the risk of algal growth. The costs of RWH maintenance is various depending on the use and purposes of the rain water. If the purpose is for drinking it demands the better filters and more frequent cleaning in general.
Table1: Estimated Average Annual Maintenance Requirements. Ariyanda, 2011 Requirement: Dry zone (Rs.) Wet zone (Rs.) Cleaning of roof Repairing gutters Repairing of filters Cleaning of roof Cleaning of tank Repairing of tank 133 280 149 133 150 221 100 - 125 100 130 150 Total 933 505
As stated in the survey made by T.Ariyananda it can be seen that the average annual costs for maintenance is about Rs.500 in the Colombo area which is situated in the part of Sri Lanka counted as the wet zone. After installing and building a RWH this will be the only cost remaining.
To have a RWH demands a responsibility and awareness about the relation between careful maintenance and water quality. Of course this is a little more work involved compared to the use of pipe borne water.
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 17
2.2.3 Usage and efficiency
RWH systems being in use in Sri Lanka at the present time are approximately around 31,000 systems over the whole country. Below you can see a picture showing the distribution of household RWH systems on the island.
Figure2: The figures are showing how many household RWH systems in use in the different
areas of the island.
LRWHF, 2012
Most of them are located in rural areas where the scarcity of water is the most. A large scale household Rural RWH project was introduced in 1995 to the country. It was under the World bank funded Community Water Supply and Sanitation Project. Since then many other
organizations and institutes have supported projects with RWH systems for water supply in the wet and dry zones.
Water from RWH systems in Sri Lanka is used for various purposes including drinking, sanitation, cooking, washing clothes, bathing, gardening and other household needs. The RWH systems are designed and constructed to meet the security of these purposes. In some of
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 18 the areas it has been stated after tests that because of the poorer quality of the groundwater, the use of rain water as drinking water is a more secure alternative. Recommendations have been made for communities with high level of fluorides in their groundwater to drink rain water collected in RWH systems instead. However the use of rainwater is not recommended for drinking and cooking in the urban areas because of the high polluted air as mentioned earlier.
The main reason for the use of rainwater for 75% of the users is the lack of alternative during the dry season. In the dry zone areas about 41% and 56% of RWH system users use the harvested rainwater for drinking purposes. Compared to the wet zone this is around 25% in both dry and wet season. Water treatment methods are applied before drinking by 70% of the users who are using rainwater for drinking. Boiling and filtering is the major methods. Other methods are chlorination and SODIS. The present drinking water supply coverage in Sri Lanka is estimated to be 78%. The population with piped borne water supply is only 38% and the rest get their supply from RWH, dug wells and tube wells. Sri Lanka has as a target to provide drinking water supply for all citizens by year 2025. To reach this goal RWH is considered as the best alternative. However a substantial percentage of domestic rain water systems owners are reluctant to use rain water for drinking. The reason is mostly because of perception and lack of awareness about the water quality and security about the RWH. The majority of the people still prefer access to pipe borne water because it is considered as social status and more reliable availability all over the year. This is not really true according to studies being made about RWH, with correct management and calculated size of equipment required, will provide better availability than the pipe borne water which often have a lack of capacity during the dry season.(LRWHF, 2012:5).
A study done in Anuradhapura area reports that about 85% of the households use stored rain water as drinking water ( Bandara,2010). The main reasons for the use of rain water as a water supply were easy access of water, cleanliness and quality assurance given by project partners implemented the RWH system. Analysis shows that the chemical and physical quality of the stored water meets the Sri Lanka standard of potable water. Potable water is the same as drinking water. Some of the samples have contained non acceptable values of E-coli bacteria but the majority of the biological water parameters were in acceptable range. Other studies like Ariyananda 2000 and 2003, reports no chemical contamination in stored rain water except high pH values in new tanks due to cement dissolving and especially in the urban areas. This considered caused by the high polluted air. High turbidity levels and color in tanks has also been shown in some studies ( Padmasiri, 1998). A study in Badulla district found the same result and found that it was likely to believe it was related to the non-application of first flush device in these systems ( Heijnen and Mansur, 1998).
Several studies have been made concerning the usage of RWH systems in relation to sex, social status, education and area. These studies can be read about in a report in the following link: (LRWHF, 2012:6).
The different purpose of the usage are here shown in tables that show how much water is being used for what purpose. This study will not further investigate this area but it can be read about in the previous mentioned link. However this study will look into reasons for using and not using a RWH system. My aim is to find how it can be more attractive for the urban households to install the RWH system.
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 19 Figure3: Reasons for use of RWH system.
Ariyananda,2011 Key:
1. No alternative water sources
2. Drying up of alternative water sources during dry periods 3. Convenient to use at homestead
4. Prefer to use rainwater
5. No one available in the household to carry water from outside 6. No cost involved
7. Low quality of water in the alternative water sources 8. Other reasons
As seen in the table the reasons for use of RWH system is mainly because no alternative of water source or the convenience of it. Majority of these advantages is related to the areas with no pipe borne water where households have to spend a lot of time fetching water from other sources. Another main reason is the no cost or low cost involved. The first reasons are not very useful when it comes to convincing urban households to increase their use of RWH system because of the access to pipe borne water in the urban areas. However the reason regarding the low cost involved could be an argument if the pipe borne treated water was not so highly subsidized by the government.
0 10 20 30 40 50 60 1 2 3 4 5 6 7 8 P e rcent ag e Reason
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 20 Figure4: Reasons for not use RWH system.
Ariyananda,2011 Key:
1. Incomplete construction 2. System is not functional
3. Harvested water is not sufficient 4. Not like to use rainwater
5. Unacceptable water color 6. Water leakage in the tank
7. Entry of other fauna into the tank 8. Have a tube well
9. Have pipe born water 10. No response
The main reasons for not using RWH system are the not satisfying function and the access to pipe borne water. As stated earlier regarding the function conclusions can be done due to lack of education and awareness about the system. A non functional RWH system and with
problems like fauna entering the tank can with correct maintenance and required equipment be to satisfaction. This is in my opinion a question of better information to change the attitude against the RWH system. Again the access to pipe borne water is a major reason for not having a RWH system. I will in later chapter study the economical benefits where I will try to find a solution in this matter.
0 5 10 15 20 25 30 1 2 3 4 5 6 7 8 9 10 P e rcent ag e Reason
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 21 2.2.4 Calculation of RWH system required
This is a calculation of the size of tank to cover the usage of water by liters required and the size of catchment area (roof). Figure 5 below shows the Colombo area. Tables are derived by Mansur´s Graphs: Mansur U. “An investigation on RWH in Sri Lanka with Emphasis on quality of rain water and system design” M.Sc. Thesis University of Peradeniya, Sri Lanka. The effective collection area is equal to the area of roof that can be reasonably used to collect rainfall. All the rainfall that falls on the collection area will not be caught. During intense rainfall, rainwater will overflow from the gutters and will not be collected. And when rainfall is very light, increased evaporation means less can be captured. Which type of roofing will also have an effect on the result, so that is why a drainage coefficient is relevant to use. This coefficient is the run off coefficient.
The Reliability is 95% in this study and the Run off coefficient is set to 0.8, because it is in Colombo area.
Figure5:Calculation of RWH system required. LRWHF,2005
As can be seen in the figure 6 below, the frequency of filling storage tank in the wet areas, where Colombo is situated, about 75% of the beneficiaries fill their tank for three times or more per year. Because of this the required water need can be covered with a smaller tank compared to the dry zone where tanks have to be maximized due to the long periods of no rainfall. And according to the recommendations of not using rain water for either drinking or cooking purposes will cut the required volume of tank to cover only other needs. The size of an average household in Colombo area is 4.4 persons. (Department of Census and Statistics, 2001). A large worldwide study done by WHO, comparing different required amount of water per day and capita, shows that the average required need in Sri Lanka is 27.6 l/d/c. About 50% of this 27.6 l are used for drinking and cooking purposes. .(Peter Gleick, 1996). Of course in the urban areas like Colombo the consumption reaches a much higher level. With an easier access to water intend to increase the water consumption. Households with pipe borne water supply that cover their entire needs seem to use more than five times the amount what is required. Non-efficient taps and leaks added to this result in consumption over the limits for defendable usage and sometimes waste of treated water. (Dangerfield, 1983). As seen in the (figure 2) a tank of 5 m3 with a catchment area or roof size of 50 m2 could almost cover the entire need that would be enough to maintain a reasonable level of household consumption. And due to the recommendations of only use for other reasons than drinking and cooking it
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 22 would be more than enough. However this requires a pipe connection as supplementary water supply source. The calculation of the size of tank is related to the small scale household. In large scale households with apartments or other multifamily buildings the efficiency and savings will be larger.
Figure 6: Frequency of filling storage tank. Strand, 2012
2.2.5 Costs of RWH system
Constructing a RWH system depends on several technical and financial considerations:
locally available materials and skills
cost – of purchasing a new tank
cost – of materials and labor for construction
space availability
locally available experience and options
local traditions for water storage
soil type and ground conditions
type of RWH – whether the system will provide total or partial water supply
(Ariyananda, 2011).
Both tanks and cisterns have specific advantages and disadvantages. The main disadvantage of cisterns is that water cannot normally be extracted by way of gravity; it requires either a bucket, hand pump, step pump or, if the topography and ground conditions are suitable, gravity can be used with the help of a pipe/tap arrangement. The table 2 below summarizes the advantages and disadvantages of each storage type:
3 22 15 26 15 16
Frequency of filling storage tank (%) of
beneficiaries
once twice three times four times five times >five times”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 23 Table 2: Advantages and disadvantages of tank and cistern. Ariyananda, 2011
Tank
Cistern
Advantages
• Above ground structure allows easy inspection for leakages • Many existing designs to choose from
• Can be easily purchased ‘off-the-shelf’
• Can be manufactured from a wide variety of materials • Easy to construct from traditional materials
• Water extraction can be by gravity in many cases • Can be raised above ground level to increase water pressure
• Generally cheaper due to lower material requirements • More difficult to empty by leaving tap on
• Require little or no space above ground
• Unobtrusive
• Surrounding ground gives support allowing thinner wall thickness and thus lower costs
Disadvantages
• Require space
• Generally more expensive • More easily damaged
• Prone to attack from weather • Failure can be dangerous
• Water extraction is more problematic – often requiring a pump
• Leaks are more difficult to detect
• Contamination of the cistern from groundwater is more common
• Tree roots can damage the structure
• There is danger to children and small animals if the cistern is left uncovered • Flotation of the cistern may occur if groundwater level is high and cistern is empty. • Heavy vehicles driving over a cistern
Ferro cement is a low-cost steel and mortar composite material. Because Ferro cement walls can be as thin as 1 cm, a Ferro cement tank use less material than concrete tanks, and thus can be less expensive. Tanks made of Ferro cement consist of a framework (or armature) made from a grid of steel or bamboo sticks reinforcing rods tied together with wire around closely spaced layers of mesh or chicken wire. A cement-sand-water mixture is applied over the form and allowed to dry or cure. Repair of small cracks and leaks can easily be done by applying a mixture of cement and water, where wet spots appear on the tank’s exterior. Developing a budget for a rainwater
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 24 system and deciding what one can afford. The reservoirs typically determine the main costs of any RWH system.
Table 3: Costs involved in building of tank. Ariyananda, 2011 Tank capacity
m3
5 m3 5 m3
Material Bricks Ferro-cement Costs in Rs. Material Labor Other (transportation, supervision etc.) Total cost Cost per m3 24300 12400 5800 42500 8500 22900 17300 2500 42700 8540 Average Beneficiary contributions 4101 4101 Cost to household 38399 38599
Beneficiary contribution has been mobilized by different organizations like LRWHF, US Aid, Plan Sri Lanka, World Vision and others, for constructing RWH systems. The average
beneficiary contribution given to households installing a RWH system is Rs.2003 for labor and Rs.2098 for materials. This covers part of the investment on an initial basis. (Ariyananda, 2011).
Total costs for installing a RWH system will with these calculations for the average
household, with an approximate need of a storage capacity of 5 m3 tank, be about Rs.38500 in the Colombo area. During a period of 10 years the costs including annual costs for
maintenance (Rs.505 in Colombo area) would be estimated to Rs.4355 a year.
Further there are other economic benefits with these constructions especially in the rural areas where the unemployment figures are high, and it is the fact of what the skilled labor generates for these people. However in the urban area where people often have less space and a smaller and easier solution is required, there is another alternative to meet the demands. This
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 25 alternative is to use a prefabricated plastic cistern. They are manufactured in Sri Lanka and cost Rs.60000 for a cistern of the same size 5m3. It has a guarantee to last 25 years which can be equally compared to the constructed alternatives before restoration needs. The plastic alternative is little more expensive but is easily installed. They come in different sizes after demand of water usage. A comparison to the costs of using pipe borne metered water to the different RWH systems will be done in a later chapter.
2.2.6 Disadvantages with RWH
Initially RWH systems were very simple. They had no lid, filter or a first flush system which led to many cases of illness using rain water in the households. The water was being
contaminated by leaves, animal leavings, mosquito larvae and other insects and pollution from the air during the first 10 minutes of rain fall. Some cases of severe illness caused by E-coli bacteria´s also appeared. Later on RWH was designed to include these features which resulted in improvement in water quality. To reduce the costs of building tanks above and underground bricks and Ferro cement became popular. However a disadvantage with high pH was found due to cement dissolving. This was later improved after the tanks were washed and flushed several times (Ariyananda, 2001).
Another disadvantage with the RWH systems is the required maintenance but it is considered as a minimal impact to the comparison to the benefits both economical and environmental. A list of found disadvantages:
WHO recommended standards on conductivity of drinking water were maintained in all the rainwater harvesting tanks
WHO recommended standards on the total hardness of drinking water were maintained for all rainwater tanks
All rainwater harvesting tanks passed the WHO recommendation on turbidity for drinking water
Overall 40% of the tested rain water tanks records No E-coli, which is the WHO recommended value for drinking water. In more than 55% of the rain water tanks the E. coli levels are less than 10 in 100 ml of water, WHO low risk value (Ariyananda, T., 2003)
Having a simple Charcoal and gravel filter and first flush systems reduce the contamination levels in the tanks markedly (Ariyabandu, R. de S., etal, 1999)
E. coli levels in the tanks receiving rain water from G.I roof is less than from other roof due to heating of the G.I roof which result in perishing of E.coli in the roof (Vasudevan, 2001)
Mosquitoe breeding is reported in some tanks. Experience in Ahaspokuna in Kandy has shown that mosquito breeding could be prevented by raring fish in these tanks (Rajkumar, 2000). Or else, if the tank is tightly sealed, it serves both in preventing the breeding of mosquito larvae and the growth of algae and thereby improves the quality. (Ariyananda, 2003).
In earlier studies it has been shown that the average use of rain water as drinking water was only 10-15% of the beneficiaries (Ariyabandu, 1999). Reason for not using rain water for
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 26 drinking purposes was mainly the people´s perception. Improvement in technology and
awareness has today increased the numbers of beneficiaries using it for drinking purpose to nearly 90%. This according to a study recently published in 3rd ABD Water Supply & Sanitation Project report.
An improvement in personal health can be seen as a result of the households increased use of water for toilets and washing. Another improvement is the social aspect about all the saved time for the households which the earlier spent on fetching water could now be better used as time to spend with their children helping them with their schoolwork (Ariyananda,1999). Other disadvantages are:
Use rain water for toilet flushing it demands a second plumbing diverted from the drinking water. During water shortages dry periods there might be a problem with flushing and if reconnecting to the drinking water pipeline there will be a risk of contamination. Catchment areas too small on small houses
Demands a lot of space which can be a problem especially in the urban environment
Require maintenance
Advantages with having a RWH system:
Sustainable solution Environmental friendly Positive hydrological effects Less or no energy required No water bill expenses Relative low investment cost
Lower use of washing powder because of more softened water Responsibility and awareness about resources
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 27
3 Economic and environmental benefits with RWH
Following chapter will treat the economic and environmental benefit with RWH systems. It contains the water usage and the costs for treated water of today how it can be cut with RWH and what the costs involved are. Further it will investigate non-revenue water in today´s water supply net. And also show the results of using rain water to recharge ground water table. It will also treat the Rain water policy in Sri Lanka.
3.1 Usages of drinking water and costs
The urban population of Sri Lanka is presently 31 % of the total population of 19.0 millions, which amount to 5.9 million people and expected to increase more with increasing
urbanization. It is predicted that in the year 2025, 60 % of Sri Lanka's population will be in urban areas (Sri Lanka Water Vision, 2025).
Urban Water supply in developing countries like Sri Lanka is usually more complex than in develop countries. Universal access to piped Water, which is at a high service level in develop countries, are less appropriate in urban areas in developing countries. There is a huge variety of different sources used by the population with costs and quantities available and the quality of the water. Sri Lanka´s urban areas have different sources of water supply which are piped systems or protected public shallow or deep wells. But it is recognized that these wells often have a high risk of contamination by waste water from septic tanks and leaching pits. The availability is too not continuous in most areas. Average duration of water availability per day is 21 hours in Colombo municipality, 20 hours in other municipalities and only 14 hours in other areas. (Aryainanda, 2007)
With the increasing population in the urban areas the supply of pipe born water will not be enough according to D. Senevirathne at the Policy and Planning Division in Colombo. This because of rising costs of production with high electricity usage in old non-efficient water treatment plants, high costs of import of chemicals for the purification process, depletion of resources of over utilization and in great delivery losses. The total treated water being
produced in Sri Lankas urban water supply schemes averages 24 million m3 monthly. That is about 789,000 m3 daily. Only 39.9% of the population is served with safe piped water supply in Sri Lanka in varying degrees of intermittent supply levels due to either low supply levels from the natural water sources or expansion of coverage over and above designed capacity. It has been estimated that the total capital funds required to increase the water supply coverage from the current level to 60% of the population is around Rs. 500 billion. (The per capita capital investment is Rs.175, 000/-per cubic meter). Today´s costs to provide 1 m3 of treated water is Rs. 40,00, but only Rs. 6,50 is charged from the consumers for the first 10 m3 and Rs.20 for up to 25 m3 which covers the most of the households monthly usage. These figures include nothing but the costs for the treatment and deliverance. Including investments in treatment plant and the pipe system, this amount would be much higher. At least Rs.125/m3 is required to repay the required capital investment. (Senevirathne, ,2012)
As seen in table 4 below the average monthly consumption is 17.22 m3 and the monthly billing about Rs.573.
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 28 Table 4: Average consumption and billing for households per month. Domestic water supply, 2011
Average Household Monthly
Consumption
(cu. m. per house connection) (a) Western Province 17.14 17.22 0.5 (b) Other Provinces 13.18 13.16 (0.2) Average Household Billing per
Month (Rs.)
(a) Western Province 566.17 573.21 1.2
(b) Other Provinces 310.23 319.03 2.8
"According to the present rate of consumption, domestic and other needs of the population cannot be met with the current supply level. Hence there is an urgent need to find alternatives to reduction of water bills through government subsidiary by minimizing usage of treated water. This could both satisfy the water requirement of the population and cut the costs of water production. Alternatives with a lower quality of water delivered through the pipe-borne system for other uses than drinking and cooking have been discussed. Potable water would then be provided by only bottled water to all citizens of Colombo. This alternative is not a sustainable solution and has a lot of both economic and environmental disadvantages. A lot of transportation and energy for plastic production would be required as an initial effect to be added with all the future effects with pollutions etc. and of course the limitation to existing water wells. Then we would not be prepared to climate changes and droughts of these wells." (George, chief manager of water development, Colombo, interview 2012-12-24). According to George an example of great misuse of treated water because it is being so highly subsidized could be seen at an Army complex that used more than 3000 m3 per day. “When an
expedition was sent out to check how come the usage was that high, they found out taps for vehicle washing never being shut off. Because of the low cost involved nobody had responded to it.” (George, chief manager of water development, Colombo, interview 2012-12-24).
The Greater Colombo area gets its drinking water from 3 different Water treatment plants:
Ambatale Water Treatment Complex
Kalatuwawa Treatment Plant
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 29 Greater Colombo Water Supply Scheme
Ambatale Water Supply Scheme
Year Commissioned : 1966 (Old Plant) : 1994 (New Plant)
Water Source : Kelani River
Water intake : 02 Pump Houses ( Old & New) : 577,000 cu.m. per day
Sedimentation tanks : 05 Tanks capacity 61,300 cu.m. each
: 04 Tanks capacity 45,000 cu.m. each
Filters : 26 (18+8) Rapid Gravity Sand Filters
Chemicals: Alum Al2(SO4)3. 14H2O : Lime Ca(OH)2 Chlorine gas Cl2
Water storage : 03 Tanks (91,000; 4,200; 6,600 cu.m.)
Production per day: 470,000 cu.m. (105 million gallons)
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 30 Kalatuwawa Water Supply Scheme
Year Commissioned : 1960
Water Source : Kalatuwawa Reservoir
Water Catchment Area : 3500 Acres
Water Surface : 320 Acres Dam - Length : 980 feet
- Height : 80 feet
Maximum Water Level : 370 feet MSL
Water Intake : Water flows to Treatment Plant under gravity
Sedimentation Tanks : 02 Tanks Horizontal flow
Filters : 10 Rapid Gravity Sand Filters
Chemicals : Alum, Lime and Chlorine
Power Generators : 02
Transmission Lines : 02
Production per day / Distribution: 68,000 cu.m.
Labugama Water Supply Scheme
Year Commissioned : 1960
Water Source : Labugama Reservoir
Water Catchment Area : 2500 Acres
Main Dam - Length : 420 feet
Reservoir Dam Height : 87 feet
Maximum Water Level : 370 feet MSL
Water Intake : Water flows to Treatment Plant under gravity
Sedimentation Tanks : 02 Tanks Horizontal flow
Filters : 15 Jewel Type (Circular) Sand Filters
Chemicals : Alum, Lime and Chlorine
Transmission Lines : 03
Production per day / Distribution: 38,000 cu.m.
Maximum Production Capacity: 53,000 cu.m. per day Figure7: Greater Colombo water supply scheme. NWSDB,2011
Ambatale Water Treatment Plant takes the water from the Kelani River, Kalatuwawa Water Treatment Plant from Kalatuwawa Impounding Reservoir and Labugama Water Treatment Plant from Labugama Impounding Reservoirs. These water sources are surface water. Because Ambatale Treatment Plant location is not near the river pumps are used to pump from the Kelani River by the two 2 pump houses on the left bank of the Kelani River. These pumps work 24 hours. Therefore a large sum of money has to be spent on electricity.
Kalatuwawa & Labugama plants receive water under gravity. The water that is found in the rivers & reservoirs are usually not suitable for drinking. The water in the Kelani River is polluted by the activities of man & animals. And effluents of the industries situated along the river, domestic wastes, storm water, and sewage-all enter the river through a system of drains & waterways. Hence the river water is not suitable for drinking. Before the water can be distributed as drinking water it has to be purified.
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 31 Purification or treatment process of the water consists of 5 steps.
They are:
Aeration
Addition of chemicals Coagulation Flocculation
Sedimentation
Filtration
Desinfection
The chemicals being used in the process are imported from foreign countries. Therefore it is an expensive method. Also securing the water quality and distribute it to the households are of course added to the costs. It is a large sum of money needed to produce safe drinking water. National Water Supply & Drainage Board, in the year 2011, spent Rs.504 million monthly to produce 24 million m3 of water. To produce 1 m3, it cost Rs.21,00. The breakup of monthly Production cost is as follows:
Electricity 71%
Chemicals 10%
Administration/ Salaries/ Repairs/ Security/ Others 13%
To cover the expenses the National Water Supply & Drainage Board are compelled to charge a fee for the water the households use. The charge is not always in proportion to that all citizens can have access to drinking water. Citizens are urged to do the following to cut their bills and water usage according to NWSDB:
To use water carefully without wasting.
To keep tap closed when brushing teeth, washing face or doing work in the kitchen.
To use water saving techniques to reduce the usage of water. Have a bottle/bag full of water in the Toilet cistern; have a faucet aerator installed in the taps to reduce flow.
To protect the water resources. Do not use it as a dumping ground for waste disposal either for domestic or industrial purposes.
To attend immediately to any water Leaks in the house. Inform the Water Board of leaks outside your premises as soon as you detect it.
Try to use alternate sources of water other than drinking water for gardening. (LRWHF, 2012:7)
There are very few rain water harvesting system in urban areas in Sri Lanka, even though there is a legislation since 2009 that every new building in urban and municipality area should have a rain water harvesting system .Few system that are being installed are in commercial and Industrial buildings. (LRWHF, 2012:8).
The state sector involved in water supply projects have been depending solely on donor supported projects funded through ADB, World Bank, JICA etc. using concessionary terms of lending. However, some of the other water supply schemes have been mooted by the INGOs and NGOs through donations received from the developed countries for meeting objectives relating to alleviation of poverty in the third world countries. The percentage of such projects
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 32 is marginal compared to those funded by bi-lateral or multi-lateral donor funded projects. This funding has made the price levels of today possible. Without further funding the price Rs.40 for treated water will go up even if investments not are included.
There are 9,500 employees attached to the NWSDB to operate and maintain the existing water supply schemes out of which 400 are fully qualified and trained engineers, accountants 60, chemists 30, geologist 14, sociologist 16, HR 28, IT 28. The balance staff consists of, clerical hands, support staff, supervisors, and skilled and casual laborers. There was a loss of Rs. 1.4 billion in2009 compared to a loss of Rs. 2.9 billion in 2008. The losses were mainly due to high cost of financing up to Rs. 1.5 billion in 2009 and Rs. 1.1 billion in 2008. Considering the majority of the water supply facilities are provided by the NWSDB which is a top heavy entity with an overall administration overhead component of Rs. 2.0 billion in 2009 and with 39.9% coverage 2011 (D.Senevirathne,2012)
There is a need to reduce Non-Revenue Water (NRW) due to illegal tapping, stand post connections etc. from a high of 40% and provision of water for marginalized poor water users up to 20% of the total number of potential piped water users. There is a need to fill the gaps in investment and institutional policies to fill the gaps in catering for the urgent needs of majority of the population with piped water supply. Some project activities to cut the losses have been done in different areas of Colombo with varied results. The results depending on several different factors like population, income, age of supply net, number of stand posts etc. In the figures below you can see a comparison between the area Borella and Kotahena.(NWSDB, 2012)
Figure 8: Kotahena area water losses. Strand, 2012
In Kotahena area the water has to be distributed over a long distance. It is a low income area with a high population. The distribution net is old. In this area no activities have been done to reduce the water losses.
29,3 3,6 0,8 65,7
Kotahena area
Billedfree water outlet meter related losses real losses
”Urban Rain Water Harvesting and sustainable water management in Sri Lanka” Page 33 Figure 9: Borella area water losses before activities. Strand, 2012
Borella is an area with a new distribution net. The area is not that populated as Kotahena and the income level is higher. In figure 9 it can be seen that real losses before any activities were 32,4%, free outlets 2,2%, illegal outlets 0,1%, meter related losses 2,5% and losses depending on fixed rates 2,7%.
Figure 10: Borella area after activities. Strand, 2012
After activities to reduce losses in this area the result was as seen in the figure 10 real losses were cut from 32% to 12%, free outlets was extended to 2,6%, also meter related losses were
60,25 2,2 0,1 2,5 2,7 32,4
Borella area (before activities)
billed free outlet illegal meter related fixed rate real losses 82 2,6 3 0,3 12
Borella area (after activities)
billed free outlets meter related fixed rate real losses
