New Delhi, Sept. 21 -- For the fourth time in five months, high coliform levels have been found in the drinking water being supplied by the Delhi Jal Board (DJB) to Janakpuri's Block A, the Central Pollution Control Board (CPCB) has informed the National Green Tribunal (NGT) earlier this week. The pollution control board said it found presence of either total coliform or E. coli in nine of 17 samples collected from houses in the neighbourhood. In its latest report, dated September 14, the CPCB said samples were lifted from houses between September 3 and 8 and tested for three parameters --total coliform (TC), faecal coliform (FC) and E. coli, all of which should be nil in drinking water. But the highest reading of total coliform in the water samples goes up to 16 million units, indicating sewage is mixing with the drinking water supply. The highest FC reading was 9.2 million units and the highest E. coli value 3.5 million units. The NGT has been hearing a plea filed in March this year by the Janakpuri A-1 Block Residents' Welfare Association, which alleged that their drinking water was contaminated by sewage leaks. Since May, the tribunal has directed the CPCB to collect samples on four separate occasions, with tests confirming the presence of E. coli total coliform, or faecal coliform in multiple samples each time. The latest report shows little has changed on the ground. "Out of 17 samples, eight were free of total coliform and E. coli. Two samples had very low levels of total coliform, but no E. coli was found, including one from a randomly selected house. In seven samples, both total coliform and E. coli were detected above safe limits. According to the Bureau of Indian Standards, neither total coliform nor E. coli should be present in 100ml of drinking water," the report said. In June, the NGT reprimanded the DJB for inaction. CPCB's first round of sample testing in the last week of May found contamination in six out of 20 samples. The DJB told the tribunal that the issue stemmed from pipelines-nearly 40 years old-being corroded. A long-term solution includes laying down a new 730-metre pipeline, the work on which commenced on August 4, the NGT was told. "The work is to be completed in 60 days from the date of starting work..." a bench headed by NGT chairman justice Prakash Shrivastava said on August 8. The bench added that the DJB will have to submit an affidavit by November 15, stating that the work is complete. HT had last week reported a similar problem in Vasant Kunj's C-9 block, where residents were also receiving water contaminated with sewage....