New Delhi, Jan. 5 -- Of the 15,600km water supply network in the Capital, nearly 18% is more than three decades old and in need of replacement, according to a report by the Delhi Jal Board (DJB). Ageing pipes are prone to cracks and leaks that can raise the likelihood of water contamination. Concerns over water supplies in cities are in focus after contaminated water in Madhya Pradesh's Indore killed at least 10 people. "There is 2,800km (17.94%) of network which is more than 30 years old," the report, accessed by HT, said. It further noted that at least half of the water (50-52%) is non-revenue water (NRW), unaccounted for due to non-metered connections, punctured pipes, thefts and leakages. NRW can cause significant financial and resource loss for utilities. DJB plans to undertake a study of the entire supply network through Japan International Cooperation Agency (JICA) or similar technical experts to revamp the supply network, the report states. This has significant implications for Delhi. The DJB currently operates nine water treatment plants across the city that supply around 1,000 million gallons water per day (MGD). According to DJB's water quality surveillance reports from December 22 and 26, of the 7,129 samples of drinking water from various parts of the city, samples from 100 locations were found to be "unsatisfactory". Some samples were taken from underground reservoirs and booster pumping stations. The localities where samples failed included DDA flats in Mansarovar Park, Puran Nagar Palam, several samples in Sector 13 Dwarka, Bhagat Enclave in Uttam Nagar, booster station at Siraspur, Gali 8 Mohammadpur, Uttam Nagar's Vijay Vihar and Kiran Garden, Vijay Colony in Burari, parts of Jonapur, Ghitorni among other places. DJB officials claimed that corrective action was taken after the samples failed. The water utility relies on testing the residual chlorine levels in the supply water samples to test their suitability, officials said. Speaking to HT, Residents' Welfare Association (RWAs) in south, central, old, and north Delhi said water contamination from sewage and drainage-related issues remain an everyday reality for them, despite multiple complaints to local authorities. "The water supply lines run next to sewage lines. Moreover, people use motor pumps during the supply hours. Broken old pipes and widespread use of pumps makes the initial 10-15 minutes of supply water smelly and contaminated," Ashok Bhasin, president of the North Delhi RWA said, adding, "Supply lines in areas like Old Delhi, Ghantaghar, Sabzi Mandi, Malkaganj, and Chandrawal are around 40-50 years old." In response, a senior DJB official said that a large-scale replacement programme of water supply lines is being undertaken in areas such as Yojana Vihar, Jagriti Enclave, Shanti Mohalla, Jhilmil Industrial Area, Dilshad Garden, Gandhi Nagar, and IP Extension. "The government has also cleared Chandrawal catchment area improvement project under which 1,000km of new water pipelines will be laid, reducing leakages and contamination issues," the official added. Atul Goel, president of United Residents Joint Action (URJA), an umbrella organisation of around 2,500 RWAs, said the entire Delhi has sanitation and water contamination-related issues, but the concern is more prominent in areas like Karol Bagh, Rajinder Nagar, Chandni Chowk, Model Town and Shakti Nagar. "Initial water supply is almost always contaminated. During idle hours, the contaminated water enters the supply network. There is an urgent need to replace the old pipelines and plug the sites where people have illegally punctured them," he added....