Of the 1,122 samples of potable water collected from homes in six districts in Tamil Nadu, NGO Consumers Association of India (CAI) found that at least 50 per cent of the water had E. Coli – faecal contamination.

According to Santhanarajan, director of CAI, 571 of the samples tested positive in a basic bacteria test.

“We added water to the dry culture that we get from the Tamil Nadu Water Supply and Drainage Board’s water test kit and let it remain for 24 hours in room temperature. If the water turns black, it means the bacteria have multiplied, and hydrogen sulphide gas is also produced. You can do this test at home. The dry culture is available at any shop selling scientific products,” he said.

CAI visited 18 centres in Erode, Nilgiris, Chennai, Kancheepuram, Vellore and Tiruchi over the past six months and asked residents to bring samples of water used in their homes for cooking and drinking.

“We also checked the levels of total dissolved solids (TDS) using a simple TDS metre that is available in the market. We found that 630 samples had more than 500 parts per million, which is over the permissible limit,” he added.

The water samples were from borewells, open wells or from piped water supplied by local bodies in these districts.

According to Kalyani Rajaraman of CAI, residents they met with were trained to do these basic tests at home and also taught to treat their water. “The basic thing is to filter and boil the water before it is consumed,” she said.

CAI founder-trustee R. Desikan said even though the Bureau of Indian Standards had set standards for potable water supplied by civic bodies across the country and notified them in 2006, the Central government is yet to make these standards mandatory.

“If these standards are made mandatory for Chennai Metrowater for instance, it would ensure that clean, drinking water is available at your home when you open your tap,” he said.

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