Closing the Tap on Bangalore’s Leaky Water
Bangalore receives most of its water from river Cauvery (1450 Million liters per day). Borewells in Bangalore also contribute to the supply to the tune of around 20 to 30%.
While bore well water is localized and decentralized in supply, the distribution losses are minimal. Cauvery water being transported for a distance of around 95 kilometers and with around 5000 km of pipes inside the city to distribute it, the losses through leaks in the pipeline are bound to happen. These pipelines have been laid from over 50 years ago, in varying sizes. Control systems like valves and pressure regulators also add to leaks at various junctions.
The water supply system in Bangalore has a bulk storage system underground/ground level tanks as well as overhead tanks. Ground level reservoirs are installed at main receiving stations. Bangalore City has 55 ground level reservoirs and 47 overhead tanks to store and distribute water. Loss of water due to leaks at storage places also add to the total loss of water.
Water supply in Bangalore is being metered at consumption points such as houses and commercial establishments. Group housing and apartments have meters at one point before it is redistributed within their premises.
Water pumped from Cauvery river is being measured at the first pumping station – Thorekadananhalli. Buster pumps lift water at additional two stations Harohalli and Thataguni before Cauvery water reaches Ground level reservoirs at Bangalore.
It is a well known fact that over 45% of Cauvery water being pumped to Bangalore is lost and is called Non Revenue Water (NRW) or Unaccounted for Water (UFW).
Water to the core area of Bangalore is distributed through 6 divisions of BWSSB and there are 26 sub divisions. The total loss of water is the arithmetic calculation of water being pumped to Bangalore minus cumulative reading of all the meters installed at homes, apartments, institutions and all other commercial establishments. What happens in between is not known and also how much is lost in which division or subdivision is also not known.
Loss of water can be attributed to leaks in pipeline, leaks in valves, leaks in tanks, theft of water from unauthorized water connections, faulty metering etc.
Bangalore city has over 7 lakh water connections / consumers. Loss of water in distribution needs to be traced to smaller unit areas of each sub division.
The water loss between River Cauvery and bulk storage reservoirs at main receiving stations in Bangalore is less than 3%. Loss in the bulk supply pipes of 250 km total length from all the four stages of Cauvery water supply is negligible or nil. However the back wash in the sand bed filters and leaks at valves account for around 3%. Bulk of the loss is inside the city limits in the distribution system of over 5000 kms of pipeline.
Bangalore water supply inflow systemWater to Bangalore is metered presently at 240 locations by using sensors for flow rate calculations. As an initiative to go closer to ward level or even smaller segments, Bangalore South division is chosen under “District Metering Area” (DMA) for assessing UFW.
Water being distributed in each of these 26 subdivisions need to be measured on a continuous basis. Unaccounted for water between each Ground level reservoirs / Overhead tanks and the consumers connected to respective reservoir need to be targeted.
The gap between outflow from reservoir and water received by the consumers connected to respective reservoir will give the quantity of water being lost. Monitoring smaller areas with metering at inflow and outflow against actual metering at consumer points will be a good indicator to assess the loss and the reason for the loss.
BWSSB has taken initiative to meter water flow at sub division levels as well as at supply reservoir levels. This will give indications on quantity of water supplied to the size of population in that area as well as accountability for loss of water.
Metering of water before distribution in a subdivision or a ward in comparison with the cumulative meter reading of connections with in that command area will pinpoint the weak points of leak. This will also assign responsibility and accountability on the officer incharge in the subdivision.
One classic example of how this works effectively:
In an apartment block of 200 houses with one bulk water supply connection from BWSSB had one meter at the entry point of water to the underground sump. Water from the sump is pumped to various overhead tanks and each house gets water on demand. Water consumption in each house is just the division of total water inflow through the meter at the sump by 200 households. It was practically not possible to know who uses how much water and there is no incentive for water conservation. Water consumption was 2 lakh liters a day.
As water shortage was prevalent and each one was blaming other for the over use of water, the decision of fixing a water meter for each of the 200 houses in the apartment was taken and implemented. Water consumption in the apartment automatically came down and with initiation of announcing the top three highest water users name on the notice board each month, water consumption reduced further. Now after 6 months of monitoring and system being stable, the water consumption in the apartment is around 1.2 lakh liters per day.
Accountability of each consumer for his consumption of water has brought in savings of 40% of water consumption.
And that is the power of measurement with water. With the newly installed lasers in the flow meters, the hope is that Non-Revenue Water in Bangalore will reduce from its 42% today to a figure that can also bring down the production costs of supplying water to the city.
Author: AK Shiva Kumar for The Alternative.
The Alternative is an online media publication focused on sustainable living and social impact.
