Challenges of Sustainable Water Supply for Cities
Lessons Learnt in Reduction of Non-Revenue Water in Colombo, Sri Lanka
W.B.G. Fernando, Deputy General Manager, National Water Supply and Drainage Board, Sri Lanka
T.W.S. Perera, Assistant General Manager, National Water Supply and Drainage Board, Sri Lanka
Key Words: Sustainability, Water Supply, Non-Revenue Water, Challenges, Lessons Learnt
Abstract
A major challenge for the sustainability of any water supply system in the world is the non-revenue water (NRW).
The situation in many Asian cities is highly alarming. Except for few numbers of cities, many urban water supply
systems in Asia encounter high NRW. Colombo, the capital of Sri Lanka is also same. At present NRW in Colombo is
about 50%. This simply implies out of 64 million gallons of water supplied every day to the city, 32 million gallons
of water does not generate any revenue for the National Water Supply and Drainage (NWSDB) which operates and
maintains the water supply in Colombo. While high NRW reduces the income, it causes many other adverse
effects. It reduces the level of service and creates the necessity for additional supplies which again generates a
need for high capital investment. Furthermore this is a well-accepted performance indicator in the water sector.
As a developing nation, the country has to rely on foreign loans and grants for new water supply developments.
High NRW has become a negative factor for obtaining funds through international lending institutions like World
Bank, ADB and JBIC etc.
NWSDB has taken many steps to reduce the NRW. However it is a very challengeable task. Even finding the
composition of NRW is a difficult task due to the very old distribution system laid in a haphazard manner.
Replacing of old distribution lines, strengthening of raiding and prosecution of illegal connections, provision of
water to the people in slums on concessionary basis and disconnection of stand posts, regularizing of metering,
billing and collection procedure are some of steps taken to address this situation. Another innovative step taken is
the restructuring of the administrative system for the city so that an officer would be responsible for all activities
within a small area consisting about 5000 service connections.
All the above measures have various challenges and limitations. The high investment for NRW reduction has also
necessary to be compared with the final output. Usually there is certain limit beyond which investing on reduction
of NRW does not yield any economic benefits. Although it seems to be very simple NRW reduction is an area
which needs very careful consideration before investment are made. The paper will elaborate on these issues and
provide a comprehensive account of this subject which will be a good lesson for any Asian city.
Introduction
Colombo was the capital of Sri Lanka from 1815 to 1978. The adjoining city “Sri Jayawardahapura Kotte” was
named as the new capital when the new constitution was introduced in 1978. However Colombo is the leading
administrative and commercial city in the country up to date. The city is administered by the Colombo Municipal
Council (CMC) for which members are selected by the people once in four years. The population of the city is
about 650,000 while there is a floating population of another 350,000 who daily travel to city for their
employment and other needs. The extent of the city is 120 square kilometers.
Colombo was one of the few countries in Asia that fortunate to get pipe born water supply about 150 years ago.
Sri Lanka was under the British Regime from 1815 to 1948 until it got independence in 1948. They have built an
impounding reservoir in 1968 and commenced piped water supply to the city. City water supply system has been
gradually improved and it was managed by CMC. The Government decided to establish an organization called “
National Water Supply and Drainage Board (NWSDB)” in 1975 to undertake all existing water supply
schemes(WSS) in the island. However only the head works in Colombo city water supply was handed over to
NWSDB. In year 2000, distribution system was also handed over to the Board, so that Board is responsible for
entire system since 2010.
At present Colombo water Supply systems has three water sources. While two impounding reservoirs Labugama
(1868) and “kalatuwawa” (1960) provides 45,000 Cubic meters per day (Cmd) and 55,000 Cmd, the new treatment
plants constructed adjacent to the river “Kelani Ganaga” provides 500,000 Cmd. These sources cater for
surrounding cities of Colombo as well. The total inflow of water to the city is288,000Cmd (64 million gallons per
day. The water produced is highly up to the Sri Lankan Standards based on WHO standards and hence there are no
any quality issues..
One of the serious problems faced by Colombo Water Supply is high percentage of Non revenue Water (NRW). At
present NRW figure stands around 50%. Although it was around 65% in 1970s, the figure was brought down to
about 50% by taking various measures. However it is still in an alarming situation. High NRW is a common feature
in urban water supply systems in many Asian countries. Hence the lessons learnt through NRW reduction will be
useful for any developing country in Asia.
Effects of NRW
High NRW in any WSS has many adverse effects as follows.
1. Reducing the revenue from WSS and thereby affecting the financial sustainability of WSS
2. Unnecessary burden on water sources for additional water or low level of service due to the inability to
provide adequate water to meet the demand
3. NRW is a key performance indicator for any WSS. Therefore high NRW automatically indicates an
inefficient WSS. This may affect seriously for developing countries where development of new WSS manly
depend on financial assistance from international lending institutions.
4. Water from outside may into the system through water leaking points thereby threatening the quality of
water
5. Creation of a bad image on the water supply authority
Causes of NRW
There are a large number of contributory factors for NRW. The major causes are given below.
1.
2.
3.
4.
Leaks in transmission and distribution pipe network
Unbilled legitimate consumption of water through public water outlets.
Stealing of water through illegal water connections and by passes.
Administrative losses created by errors in meters, reading errors of meters etc.
Contribution of each factor for making total NRW is generally difficult to be found. This is usually attended by
selecting a pilot area and thoroughly measuring or estimating the water loss due to each factor. However accuracy
of results will depend on the extent to which the sample represents the whole area. Several such studies have
been carried out in Colombo to find the contribution of each factor for NRW and based on them a reasonable
break down can be given as shown in Figure 1.
Percentage
Factor
Contribution
For NRW
Leaks in transmission and distribution system
30
Legitimate unbilled water consumption
10
Stealing of water
6
Losses due to administrative errors
4
Figure 1
Reduction of NRW
As high NRW in Colombo city is a critical factor for NWSDB, various steps have been taken during last two decades
to address this situation. These steps and the success of them are briefly described below.
Water Leaks in Transmission and Distribution System
The total length of the water distribution system in Colombo city is about 720 KMs. The pipe network is very old.
Out of the total system, about 600km are of cast iron pipes laid about 100 years ago. The majority of rest is also
Ductile iron and steel pipes. There is only about 50km of PVC pipes laid during the last two decades. Due to the
aging of the pipe system, there are many water leaks occurring every day. A comprehensive leak repairing system
is in operation for last few years. However when one leak is repaired, the same pipe starts from leaking at another
place. Therefore although leak repairing is compulsory for the maintaining of the service, it is not a permanent
solution for the problem. Generally replacement of pipes is the permanent solution. This has been quite difficult
for NWSDB due to the lack of necessary funding. Even with the limited funding replacement of pipes has been
badly affected by two reasons.
1. As the funds are limited, pipes needs to be replaced on priority basis. A detail study of the distribution
system is required for this purpose. This is usually attended by establishing District Metering Zones(DMZ)
and measuring in those DMZs. Isolation of a part of distribution system and fixing of meters to measure
the inflow is required in this process. But in Colombo, as the pipes have been laid in a haphazard manner
this is quite difficult. Therefore identifying the worst areas is difficult.
2. As the distribution system is very old, now many pipe lines are located in the middle of roads and
sometimes under the buildings. There are no enough space to lay pipe lines along roads. Even pipe line
repairs are also carried out only in night time, due to the heavy traffic congestion in the city. This factor
also seriously affect whenever new pipe laying are planned
NWSDB is now planning to replace all old pipe lines with assistance from donors on priority basis and intends to
complete this process within next 5-10 years.
Other than old pipes quality of workmanship as well as materials used also affects water leakages in the
distribution system. Having understand the importance of this factor, now NWSDB has taken measures to have
strict control in this connection.
Unbilled Legitimate Consumption
Out of 650,000 population in Colombo about 50% lives in underserved settlements(US) ( more commonly known
as Shanties). According to the statistics of CMC, there are about 1150 such settlements in the city. The number of
families living in a settlement varies within a large range from 20 to 400. About 50% of families in US, have
individual water connections whereas the rest depends on water obtained through public water out lets. There
are three types of such outlets. People get their drinking water needs from public stand posts, while there are
number of water taps provided for public toilets and public bathing places. As at December 2010, there are about
1800 public stand posts, 1600 toilet taps and 700 common bath taps. The quantity of water used through these
outlets has been estimated to be about 10% of the total supply to the city. These families are living in the city for
several decades and many common taps have been provided by CMC, even before billing for water is started in Sri
Lanka in 1983. At present no one is paying for the water used in USs. However NWSDB is definitely not in a
position to stop the water supply to them due to humanitarian and political reasons. Other than losing the
revenue this has several other bad effects.
1. There are no proper drainage facilities around many public water taps. Therefore water is stagnating. In
case there is low pressure in the pipe lines, there is a possibility of entering polluted water to the system
through leaking points. This may seriously affect the whole system.
2. There is no any control of water used at public taps. Some time they may be kept open for long hours.
This will badly affects service of other consumers who live closely and pay for their water.
NWSDB has taken several steps to reduce the NRW due to the usage in water in USs. A special programme was
started few years back ( Knows as Randiya programme – Randiya means golden water) to provide individual
connections to houses in US at a very concessionary rate. They can obtain water connections for about 20% of the
normal fee. This payment is also allowed to make in installments for 3 years. After providing substantial number of
connections in a US the public stand posts are completely removed or reduced. Number of toilet taps and bathing
taps are also reduced. This programme has been succeeded to provide water connections to about 50% of the
families living in USs. However there are certain limitations for this programme as follows.
1. In some US, the extent of houses are very small preventing fixing of a single in their houses
2. The pathways between houses are very narrow preventing laying of laying of pipes
3. Lack of drainage facilities
4. Attitude of people which assumes that government is responsible to provide them with free water
5. Although water for domestic uses are obtainable by this way, no possibility of constructing toilets and
bathrooms due to the lack of spaces
By taking above steps, NWSDB believes to reduce the NRW in USs by about 50%. In order to address the balance
NRW in US, efforts have been made to establish consumer societies for common taps to collect money and pay for
water. However this has not been succeeded due to poor participation from the community.
NRW due to Stealing of Water
It is believed that there are considerable number of illegal water connections in the city. Some of these
connections may have been provided even before water billing was started in year 1983. About 12,000 illegal
connections have been detected and regularized in the last 10 years. In addition there are a large number of
bypasses found specially in commercial places. Although strict measures have been taken in this regard, it is still
believed that about 6% of supply of water to the city , is illegally used. A separate section has been established to
address this situation. They continuously check suspicious places and take further action in this regard. Recently
necessary laws have been passed to increase the fines on water stealing. Public is also rewarded for providing
information about such places. Mass media is used to aware the people on serious punishment they may receive
for stealing of water. Steps have been taken to seal the water meter to avoid possible tampering and use of
prefabricated Galvanized Iron pipe section to fix the meter. Furthermore close attention is placed on the variation
of monthly consumption of commercial consumers who regularly use a large quantity of water.
NRW due to Administrative Errors
There are a number of reasons connected with the administration of a water supply scheme whereby substantial
NRW may be created. More common reasons are as follows.
1. Issuing bills on estimated basis without reading meters due to lack of meters, lack of meter readers, not
taking the meter reading on scheduled dates etc .
2. Under reading of water meters
3. Delay of issuing bills for new connections
4. Purposely providing wrong meter readings for less consumption
It is believed that in Colombo about 4% of NRW is created due to above factors. NRW in this area could be
brought to a minimum by adopting effective administrative systems. Following steps are taken to reduce NRW due
to above factors.
1. Replacing of all defective meters promptly
2. Ensuring that all connections are fixed with water meters
3. Programming meter reading in a proper way to take all meter readings on scheduled dates
4. Random checking of water meters for their accuracy
5. Reconciliation of number of connections each month with the number of consumers in the billing records
6. Paying careful attention on meter readers to avoid providing any wrong readings
NWSDB has been succeeded to reduce NRW by about 2% by taking above steps to address administrative losses.
Innovative Approaches Made for Administration
NWSDB had taken many steps to address the NRW water issue for many years. However results obtained were
minimum. When the problem is further scrutinized, It was found that low commitment of officers involved is a
major setback in addressing the NRW issue. Various activities related to operation and maintenance of Colombo
city water supply system were handled by a set of officers and coordination among them was found to be poor.
On the other hand activities are too decentralized so that no one is ready to undertake the responsibility about
certain activities. Preparation of estimates for new connections, provision of connections, attending to water
leaks, meter reading and commercial matters, attending to consumer complaints, NRW reduction activities are
handled by various sections and the interrelation among them is poor or not at all . Hence new administration set
up was introduced, Entire city was divided in to 22 zones and each zone was placed under a single officer with
adequate supporting staff. The Zone officer has to attend all matters in his zone and directly responsible for all
activities including reduction of NRW. The number of consumers assigned to a particular officer is between 50006000 so that he can pay adequate attention for all matters. Action has been taken isolate the area assigned to the
Zone officer and meter and measure NRW separately for the Zone. This system is in operation for one year now
and positive result are already seen. NWSDB intends to provide more facilities to Zone officers in future and
strength this system of administration.
Challenges
Reduction of NRW in Colombo city is of high priority for NWSDB. NWSDB has paid its highest attention for this
purpose. While pipe replacement can only be attended by part by part due to the limitation of funding, NRW due
to other factors can be considerably reduced if all above steps are taken with high interest. High commitment is
also required in addition to various resources to achieve this objective. Therefore NWSDB intends to reduce NRW
at least to 40% within next five with only a part of pipes are replaced.
Conclusions
With the experiences gained and lessons learnt through engaging NRW reduction of Colombo city, following
recommendations could be made for any Asian city where NRW reduction has become necessary. While some
recommendations are applicable for new water supply systems, many could be applied for existing systems.
1. Correct assessment is a prime requirement for NRW reduction. Without knowing the present situation
correctly it is not possible to address the issue. Hence correct measuring of NRW is important. Isolation of
the required area and measuring the inflow using bulk meters are essential. If new water supply system is
constructed provision must be made for such measurements. If it is for an existing system, particular area
should be isolated and fixed with bulk meters, although this may be quite difficult.
2. Composition of NRW is important in order to address the problem for an existing system. This must be
carried out by selecting a sample area and analyzing the problem in depth.
3. Using high quality materials and better workmanship are necessary to be maintained for all new
constructions and pipe line repairs. A comprehensive pipe replacement programme is required for all
existing systems.
4. Provision of free water must be kept to a minimum. If public stand posts are unavoidable due to social
reasons, an effective method for collecting money for stand posts should be introduced.
5. Stealing of water should be completely stopped. This may be achieved by awareness programmes and
imposing relevant laws strictly.
6. An effective operation, maintenance, billing and collection system must be introduced. Timely meter
replacement, using high quality meters and employing trained and committed meter readers will keep the
administrative losses to a minimum.
7. Entire distribution system should be divided into smaller zones and there must be a single officer
responsible for the Zone. If a new water supply system is constructed, this factor must be considered at
the planning stage, so that zoning and isolation could be done easily.
8. Regular monitoring of NRW and comprehensive planning for NRW reduction is essential, in order to keep
the investment for NRW reduction at the optimum level.
Acknowledgements
The authors wish to acknowledge the assistance provided by the staff of Colombo city water supply system in
preparing this paper.
References
1. Cooperate Plan for NWSDB (2011-2016)
2. History of Water Supply in Sri Lanka( M.J. Ferdinando)
3. Annual Report – NWSDB – 2008
4. Water Loss Reduction for Colombo City ( Third ADB Project)