Given the rapidly increasing urban population, water utilities across the country are facing difficulties in delivering basic services such as clean drinking water and sewage treatment. Meeting the rising consumer demands becomes even more difficult when a large volume of the water supplied is lost due to leakages, faulty pipelines and unauthorised connections. Non-revenue water (NRW), that is, the water lost before it reaches the customer, accounts for roughly 41 per cent of the total water supplied in the country. It is typically measured as the volume of water lost as against the net water generated, or the volume of water lost per km of the water distribution network per day. However, it is not just water that is lost, it is also the energy used to produce and distribute treated water that is wasted.
Municipal corporations across the country have been taking several measures to reduce NRW and improve their operational efficiency. These include the use of good quality pipes and fitting materials, selection of service pipes based on soil conditions, improvement of distribution systems, and renovation and replacement of pipes. The New Delhi Municipal Council (NDMC) and the Municipal Corporation of Chandigarh (MCC) are two such utilities that have taken initiatives to improve their water supply infrastructure and reduce the percentage of water lost due to leakages.
Current practices and key initiatives
NDMC covers an area of 42.74 square km, accounting for only 3 per cent of the city’s area. The area has a fixed population of 232,255 and a floating population of 1,500,000. The municipal corporation requires 127.71 million litres per day (mld) of water, of which only 5 mld is met through tube wells.
Currently, the civic agency is facing challenges such as low water pressure, contamination of water, pipe leakages and water pilferage. NRW accounts for about 39 per cent of the total water supplied by the utility. NDMC has taken several steps to reduce water losses and associated costs, prevent leakages and ensure pressure management in the system.
NDMC has also set a number of targets to improve the quality of water services. These include providing 24×7 uninterrupted water supply, ensuring 100 per cent water supply coverage, reducing the NRW level to 20 per cent over a period of two years and ensuring 100 per cent metering of water connections. Further, the utility is planning to take steps to improve the quality of fresh water by reducing contamination, increase the efficiency of the municipal staff, address consumer complaints in a timely manner, replace water pipelines, reduce energy consumption and increase municipal revenue.
Chandigarh is divided into seven zones and each zone is served by a dedicated independent water works department. Before 1983, the city relied only on tube wells for water availability. However, after an agreement was signed with the Ministry of Home Affairs in 1983, the city started to receive water supply from tube wells as well as from the Bhakra canal (Kajuali). The average daily water supply in the city is roughly 245 litres per capita, with 10 hours of supply in a day to urban areas and six to eight hours to rehabilitated colonies.
Currently, NRW accounts for roughly 38.7 per cent of the total water supplied to the city. The high level of NRW is a result of ageing infrastructure, growing urban population, inadequate network coverage, pipeline leakages, illegal/unauthorised service connections and high water pressure, among others. The techniques deployed by MCC for leakage detection in the city are impulse response analysis (IPA) and the transient damping method (TDM). Under IPA, a pseudo-random binary signal is sent to the pipeline system using an oscillating valve, after which the measured pressure response is compared to the leak-free and blockage-free calculation. A spike in the impulse response helps detect a leakage or a blockage. On the other hand, under TDM, leakages in pipelines contribute to damping of transient events, which helps in finding the location and magnitude of leaks.
The key elements of the utility’s NRW reduction strategy are water audit, water balance analysis, NRW assessment and improvement/action plan. A water audit helps assess the level of NRW and develop a programme for NRW reduction. However, there are various challenges faced during water audits. These include the unavailability of network drawings, intermixed network zones/water zones, old/faulty/buried consumer meters, leakages in old networks, leakages in household service connections and unauthorised connections.
In view of the ever-increasing water woes, MCC has devised a strategy to reduce its NRW. The various steps taken under this strategy are water audits for the entire water supply system, energy audits for all pumping installations, study of district metered areas (DMAs), installation of the supervisory control and data acquisition (SCADA) and online monitoring systems, creation of web portals, and introduction of the smart water metering concept.
For conducting regular energy audits of its pumping installations, MCC has signed an MoU with Energy Efficiency Services Limited (ESSL) for a payback period of 13 years. In a recent survey on 478 pumps, ESSL has recommended the replacement of 276 old pumps with energy efficient pumps. The initial expenditure required for replacing the pumps is Rs 150 million and the same is expected to translate into savings of Rs 130 million. Further, MCC has introduced the concept of performance-based contracts for smart water supply management. This contract entails geographic information system-based asset mapping, detailed hydraulic modelling of the water supply system, establishment of DMAs, installation of electromagnetic flow meters with SCADA control at all important delivery points (at the outlet of water treatment plants and at the entry of DMAs), active leakage control, and leak identification and reduction on a continuous basis. Besides, under the Smart Cities Mission, MCC plans to issue a requests for proposal for the installation of household meters with an automated meter reading (AMR) facility.
A pilot study was undertaken by MCC in Manimajra to implement all these initiatives. It was a household-level survey to determine the number of metered connections in individual houses/properties. The measures that were proposed for leakage control include assessment of water losses in the system by implementing modern leak detection technologies; repair and replacements of leaking parts or structures; replacement of old pipes and reconditioning of lead caulked joints; and installation of the SCADA system. The measures proposed for controlling NRW included the installation of smart metering devices for all connections; adoption of efficient methods for recording water consumption (implementation of AMR/advanced metering infrastructure); deployment of appropriate mechanisms to convert flat rate connections into metered connections; and regularisation of illegal connections.
The way forward
NRW is a key performance indicator for water utilities. High levels of NRW indicate a poorly managed water utility. This also adversely affects the financial health of urban local bodies. Several initiatives have been undertaken to address this issue. These include metering of household connections, leakage detection, modernisation of infrastructure, auditing, and replacement of pipelines.
The steps taken by NDMC and MCC have helped them reduce their revenue losses and improve service delivery. Going forward, the two civic agencies have also set targets to further reduce the NRW component through a number of initiatives. The successful implementation of these initiatives will require a greater level of private participation, manpower training, implementation of rational user charges to increase revenue collection, and public support.
Based on presentations by Ajay Gupta, Superintending Engineer, NDMC, and Sanjay Arora, Superintending Engineer (PH), MCC, at a recent India Infrastructure conference