The DJB was reacting to a complaint from the All India Institute of Medical Sciences (AIIMS), as also to a report in the Hindustan Times on November 11, “Delhi’s water carcinogenic: New Tests”.

Probe by the DJB into AIIMS’s complaint that bad quality water was being supplied to it instead blamed the institute for the contamination, saying it was mixing groundwater with water supplied in pipes.

Old, leaking pipes carrying water carrying DJB-supplied water to thousands of homes across the city are also a source of contamination and the board said the onus was on the consumer — and not the DJB to check such contamination.

“We have testing labs at all our water treatment plants and we ensure Delhiites get clean water,” Sanjam Chima, consultant (public relations) DJB, said, reacting to the HT report.

Tests conducted by the National Environment Engineering and Research Institute in July, September and November 2006 at DJB’s water treatment plants show water released from all the plants conform to approved standards, she said.

With respect to presence of toxic substances called total trihalomethanes (TTHM) in water supplied by the DJB, the tests found them within World Health Organisation (WHO)-approved limits.

But the DJB did not rule out TTHM contamination on the way.

Central Pollution Control Board officials said TTHM, a byproduct when chlorine reacts with humic and fulvic acid, may find its way into water when outside particles enter pipes carrying water.

Chima said under laws it is the task of consumers to replace pipelines from DJB reservoir to homes every 15 years, something that is seldom done. “In many old colonies of Delhi, pipelines are 30-40 years old with cracks. Replacing the pipelines are the responsibility of consumers, not the DJB,” she said.

In approved colonies, the job is done either by the DDA or MCD, the cost borne by way of development charges taken from consumers.