The report also flags glaring lapses in water testing, monitoring, and infrastructure including use of carcinogenic polyelectrolytes in treatment process.
More than half of the ground water samples tested between 2017 and 2022 were found to be unfit for drinking and pose a “serious risk” to public, said a report by the Comptroller and Auditor General (CAG) of India, raising serious concerns over the quality and safety of drinking water supplied in the national capital.
The report, tabled in Delhi Assembly on Monday, also flags glaring lapses in water testing, monitoring, and infrastructure including use of carcinogenic polyelectrolytes in treatment process.
The CAG report, titled “Functioning of Delhi Jal Board”, said, “Quality testing of groundwater was carried out on 16,234 samples by the eight zonal laboratories of the DJB during the period 2017-18 to 2021-22. Out of the total samples tested, 8,933 samples (55 per cent) were found unfit for potable purposes.”
The percentage of failed water samples ranged from 49% to 63% during the audit period. “Supplying groundwater from areas where samples were found unfit poses serious health risks to the public,” it added.
To be sure, Delhi has been progressively reliant on groundwater sources to meet its water supply demands. Of the city’s 1,000 MGD (million gallons per day) water supply, around 135 MGD comes from groundwater sources like tubewells.
The CAG audit also flagged the practice of mixing treated and untreated water. “During test check of records and information furnished by the DJB projects division and laboratories, it was found that 80 MGD to 90 MGD raw water from borewells/ranney wells was supplied to UGRs/consumers directly without treatment by DJB during 2017-18 to 2021-22, thus compromising water quality which could be hazardous to the health of the people,” it added.
An HT report published earlier this month also found that nearly 44% of the samples violated basic microbiological safety standards. Laboratory analysis of a seven-day sampling exercise at 18 complaint-prone locations revealed that eight samples tested positive for total coliform or E. coli – indicators commonly associated with faecal contamination in water.
All eight contaminated samples came from domestic tap connections. Strikingly, three of these domestic samples did not meet even the threshold for “bathing water”.
Additionally, the CAG report flagged shortages of staff and equipment at the DJB testing labs, adding that water was not being tested as per Bureau of Indian Standards (BIS) norms. Against 43 parameters, “DJB was testing only 12 parameters during the water treatment process,” it noted.
As a result, for instance, there was a shortfall up to 69% at the Dwarka WTP and 62% at the Sonia Vihar WTP in testing of required parameters at all stages of the water treatment process.
The audit report also notes even though DJB draws raw water from borewells, this water was only tested on four of 46 parameters. Critical parameters like “toxic substances” “radioactive substances”, “biological tests”, and “virological tests” were not conducted. Tests for the presence of heavy metals like arsenic, copper, lead, etc. in the water were also not conducted by DJB. “The presence of radioactive substances and heavy metals in drinking water can be fatal as these substances may cause damage to the liver, kidney, and intestine, and also cause anemia and cancer in humans,” the report added.
CAG also flagged the continued use of banned polyelectrolytes at Haiderpur plant. In a DJB memorandum issued in May 2016, it banned the use of polyelectrolytes at all WTPs and recycling plants due to their carcinogenic properties. “Audit observed that the private operator of recycling plant at Haiderpur WTPs was using polyelectrolytes in the treatment process since 2017-18 despite it being prohibited by the Testing and Quality Control Department of DJB,” the report said.
CAG report has also noted the increase in the failure rate of the number of water supply samples internally tested by DJB’s labs.
During the period 2018-19 to 2021-22, cases of samples failing in “physical quality tests: out of the total sample collected more than doubled and increased from 0.81% to 1.74% of the total samples collected. Similarly, samples that failed “chemical quality tests” also doubled from 0.83% to 1.76%. This shows a deteriorating trend in the quality of water being supplied to residents of Delhi by DJB, it noted.