One of the major issues that affects water supply services in Goa is the considerable proportion of non-revenue water (NRW), that is, the difference between the amount of water put into the distribution system and the amount billed to consumers. NRW in Goa was as high as 45 per cent of the water supply, resulting in a huge loss of water and revenue due to corroded pipes, leakages and theft.
Given this situation, it became imperative for the government to reduce the ratio of NRW before undertaking any large-scale water supply projects. In August 2007, the Goa government launched the Capacity Development Project for Non-Revenue Water Reduction in Goa. The project was undertaken by the Goa Public Works Department (PWD) with technical assistance from the Japan International Cooperation Agency (JICA), and was aimed at adopting advanced technologies at various stages of water supply distribution.
The measures taken to reduce losses and increase efficiency include leak detection in the main and distribution pipelines, rehabilitation of old and obsolete pipeline infrastructure and the installation of water meters.
Under the project, a study was conducted of the state-wide NRW situation, following which pilot projects were undertaken in three areas. During the formulation of the plans, it was decided that the success of the initiatives in the pilot areas would guide the future NRW reduction plans.
The areas for the pilot project were selected on the basis of parameters such as the number of household connections in each area, the ease of collecting information regarding pipeline leakages, the water supply scenario and the number of ongoing projects. On the basis of these, Curtorim, Khadpaband and Moira were selected as the pilot project areas. These areas are part of the Salaulim, Opa and Assonora water supply schemes respectively. Three separate teams were formed for the implementation of the project in the individual areas. One of the distinguishing features of the project was the active involvement of the public relations team in creating awareness about the benefits of the project among the general public. This ensured smooth operations during the course of the project activities.
The first step of the process was the collection of data pertaining to the quantity of water supplied, amount of water billed, meter condition, etc. as part of the study. This helped the state authority to formulate the roll-out and action plan for the pilot project.
Following the development of the plans, the Goa PWD and JICA prepared a topographical map and pipe network drawings for the pilot areas. For this purpose, it used the geographic information system (GIS) developed under the 24×7 water supply project, which mapped the transmission mains and distribution mains across the state as the base map. The map was updated to include information on the number of household connections and water meters collected by the respective teams. In order to reach the goal, the teams collected information on valve locations, pipeline alignment and diameter, along with the type of material used. Next, a GIS pipeline network map was prepared using the Quantum GIS software. The GIS software was then used to extract information regarding the transmission lines, rising mains, distribution lines, service lines, details about functioning and non-functioning meters and details about water sources during the entire course of the project.
After completion of the mapping, the various teams conducted leak detection surveys using listening bars (stethoscope rods) on the water mains. Leak detection was conducted along distribution pipelines during the night when water consumption was minimal. The teams then undertook repairs of the faulty distribution and service connection pipelines.
Household surveys were conducted using portable ultrasonic flow water meters to collect information regarding the quantity of water reaching households. Apart from this, in order to isolate the pilot project areas for monitoring water received by these areas, permanent bulk flow meters were installed on pipes at the boundary of the pilot project. The choice of permanent bulk flow meters was based on the shape of the pipeline system in these areas. Most of the pipeline systems in the selected areas were shaped like a tree branch and not a network. Since water supply could be stopped downstream and closed at the boundary, bulk flow meters were installed at such points instead of gate valves. Following the collection of data by flow meters, the billing data issued by the Revenue Section (Cell) was summarised for each pilot project area in a time series. Subsequently, the billing data sheet, the results of the household survey and GIS map were linked with each other. This assisted the authorities in estimating the accurate NRW ratio in the three areas. The estimated NRW figures were used as a base for future reference.
These processes were classified under “baseline”, “interim” and “final” stages. Major activities for NRW reduction such as leak repair and disconnection of unauthorised consumption were undertaken during the period from “baseline” to “interim”. On the other hand, activities such as the replacement of malfunctioning meters and improvement of meter reading by special reading were undertaken during the period from “interim” to “final”. After the final stage, the NRW ratio was reduced from 45 per cent to 18 per cent in Curtorim, 58.7 per cent to 34.4 per cent in Khadpaband and from 53 per cent to 36.1 per cent in Assonora.
Based on the success of the pilot project, JICA issued specific guidelines for implementing the project in other areas of the state. These include undertaking works aimed at the reduction of leaks in pipelines, installation of the necessary number of gate valves for stopping the flow of water during leak repairs, replacement of faulty and obsolete pipes, metering of all water connections and minimisation of flat rate connections.
On the basis of these, a long-run NRW reduction plan and an annual NRW reduction plan were formulated for various areas in the state. Also, NRW reduction projects for areas outside the pilot zones, known as district metered areas (DMAs), were formulated. A total of 10 DMAs have been selected with around 1,000 water connections each. Using GIS, details on leakages and water meters have been collected for these areas. The combination of data analysis and adherence to the guidelines issued are expected to reduce the ratio of NRW in DMAs as well. Besides, the PWD has already set up a dedicated helpline, which enables customers to report leakages in the pipelines. The department is also planning to upgrade the leak detection methodology to include the use of noise loggers, hydrogen gas injections and ground penetrating radars.
Further, as part of the long-run NRW reduction strategy, plans are afoot to set up a central NRW control unit in the PWD head office. This control unit will be authorised to execute management activities such as the preparation of an NRW reduction plan, monitoring of activities, collection and processing of data, securing the budget and carrying out the necessary training.
Going forward, more concrete steps are needed for the introduction of leakage control technologies across cities, repair and maintenance of non-functional meters and replacement of obsolete and faulty pipeline infrastructure. A piped water supply network with operational meters should be developed to reduce losses incurred during the distribution of water. Most importantly, capacity building of water utilities and effective implementation of volumetric tariffs will be crucial for sustainable NRW management.
The Goa government’s ambitious plan to reduce the NRW ratio across the state to 20 per cent by 2019 looks achievable, given the successful implementation of the pilot projects. The lessons learnt from the pilot projects in Goa should be utilised by other cities such as Delhi, Bengaluru and Hyderabad, which face the problem of a high NRW ratio. This will not only assist various urban local bodies in meeting the growing water demand in various areas but will also relieve them of the financial crunch hindering the uptake of a number of initiatives.