Managing the high levels of non-revenue water (NRW) has become a prime concern for water authorities. In urban India, a significant quantum of water provided by service utilities remains unaccounted for because of illegal connections, water thefts and leakages in the distribution system. The Kerala Water Authority (KWA), which has been facing similar issues, has started adopting advanced technological solutions for more effective detection of leakages. While some of the solutions, such as SmartBall and Sahara, are based on advanced leakage detection technologies, conventional tools are also being deployed by the water authority.
The KWA manages a total of 2.6 million domestic water connections as against a population of 30 million. Other than street pumps, all the water connections in the state are metered. About 95 per cent of all the water meters have been working efficiently.
One of the main issues faced by the KWA is low coverage of water connections. Further, it lacks the capability of tracking water from the production side, resulting in the NRW level being as high as 40 per cent. Of the water supplied in the state, 40-50 per cent is not billed. Another issue is the dated pipeline network, because of which about 50 per cent of the leaked water does not reach the ground surface, making it virtually impossible to detect the exact location of the leakage. Other challenges include intermittent water supply, and recurring operations and maintenance costs.
The KWA embarked on a pilot leak detection study in 2004, with the primary aim of reducing NRW levels. The study was conducted in Coimbatore and Kozhikode, with assistance from the Japan International Cooperation Agency. It showed high NRW levels in both cities, primarily due to under-reading by the installed meters. In order to address the problem, the KWA purchased equipment for detection of leakages in pipes in 2008, following which a dedicated NRW unit was set up in 2012.
Since then, the KWA has been using a variety of innovative methods for identifying the sources of leakages. In the case of a major leak at Thiruvananthapuram, the acoustic leak detectors deployed at the time were not able to locate its source. The KWA then used the sequential valve closing and control of flow method to identify the source. In a similar instance, a water shortage was reported in Nattika village of Thrissur district. Suspecting unidentified leaks, survey works were carried out in the main distribution pipeline, which showed inadequate inflow of water at a nearby plant. Repeated measurements at various points revealed a leakage of 3 million litres per day in the main pipeline. Leak detectors were then deployed to identify the exact fault location so as to rectify them.
The KWA has been instrumental in deploying advanced leakage detection tools for easier and faster detection of leakages in water distribution pipelines. SmartBall is one such technology. It is a free-swimming foam ball with instruments placed inside an aluminium alloy core. It calculates the location of a leak by detecting acoustic pulses emitted by the ball at receivers attached to pipe appurtenances. The location of the leak relative to the position of the receiver is determined by analysing the time the pulses take to arrive. This survey method has been deployed by the KWA in a number of instances for identifying leakages.
Another method adopted by the KWA is the Sahara pipeline inspection system. This system can be deployed for detecting leaks, air pockets, inline valves, branches, and redundant and illegal connections. The system can also detect structural issues such as corrosion, tuberculation, presence of debris and partial blockages in waste and sewage mains. It consists of a precision locator, known as the Sahara locator, which is equipped with an extremely low frequency transmitter that can be detected by sensors inside the pipeline. This enables easy communication and accurate data collection through pipelines.
Currently, the KWA boasts of a variety of equipment solutions for detecting leakages, ranging from mechanical listening sticks to electronic listening sticks, ground microphones (Omikron) and leak noise correlators (ZetaCorr). It is also equipped with flow and pressure measurement instruments (ultrasonic flow meters and flow and pressure loggers) and underground asset detection and mapping instruments (metal valve locators, metallic pipe locators, non-metallic pipe locators and ground penetrating radar).
The way forward
Water authorities across the country have started taking initiatives to reduce NRW levels and plug leakages, using both conventional and advanced techniques. Going forward, the full potential of the advanced technologies can be realised only when the concerned agencies deploy skilled manpower as well.
Based on a presentation by Praveen K.S., Executive Engineer, Operations, KWA, at a recent India Infrastructure conference