A report by the Comptroller and Auditor General (CAG) of India has raised major concerns about drinking water quality in Delhi. The report said more than half of groundwater samples tested between 2017 and 2022 were not safe for drinking. It warned that this poses a “serious risk” to public health.
The audit, titled “Functioning of Delhi Jal Board,” found that out of 16,234 samples tested, 8,933 samples — or 55% — were unfit for potable use.
Wide Gaps in Testing and Monitoring
The report highlighted serious lapses in testing, monitoring, and infrastructure at the Delhi Jal Board.
It said the failure rate of water samples ranged between 49% and 63% during the audit period. It added, “Supplying groundwater from areas where samples were found unfit poses serious health risks to the public.”
Delhi depends heavily on groundwater. Out of its total water supply of 1,000 million gallons per day (MGD), around 135 MGD comes from sources like tubewells.
Untreated Water Supplied to Consumers
The audit found that authorities supplied untreated water directly to consumers in many cases.
It stated that 80 to 90 MGD of raw water from borewells and ranney wells was sent to reservoirs and households without treatment between 2017 and 2022. The report warned that this practice “compromising water quality which could be hazardous to the health of the people.”
Contamination Found in Tap Water
Earlier findings also showed serious contamination in water supplied to homes.
Tests conducted at complaint-prone locations revealed that nearly 44% of water samples failed basic microbiological standards. Eight samples tested positive for coliform bacteria or E. coli, which indicate faecal contamination.
All contaminated samples came from domestic taps. Alarmingly, three samples did not even meet the standard required for bathing water.
Incomplete Testing Raises Red Flags
The report pointed out that testing practices were inadequate. Although 43 parameters are required, the Delhi Jal Board tested only 12 during treatment. This led to major gaps, including a testing shortfall of up to 69% at Dwarka and 62% at Sonia Vihar treatment plants.
Groundwater drawn from borewells was tested on only 4 out of 46 required parameters. Critical checks for “toxic substances”, “radioactive substances”, “biological tests”, and “virological tests” were not carried out. Authorities also did not test for heavy metals like arsenic, copper, and lead.
The report warned, “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.”
Use of Banned Chemicals Continues
The audit also flagged the use of banned substances in water treatment. It found that a private operator at the Haiderpur plant continued to use polyelectrolytes despite a 2016 ban due to their carcinogenic nature.
The report said this practice continued from 2017 onwards, ignoring safety rules set by the testing department.
Water Quality Shows Declining Trend
The report noted a worsening trend in water quality. Samples failing physical quality tests rose from 0.81% to 1.74%. Similarly, failures in chemical tests increased from 0.83% to 1.76% between 2018-19 and 2021-22.
This indicates that the overall quality of water supplied to Delhi residents has deteriorated.
Rising Water Loss and Unequal Supply
The audit also highlighted major water losses in the system. Transmission losses increased from 16% to 21% between 2017 and 2022. At the same time, water supply remained uneven across different zones.
In some areas, per capita supply was less than 20 gallons per day, far below the required 60 GPCD.
Massive Revenue Loss Due to Water Theft
Delhi also faces serious issues of water loss and theft. Non-Revenue Water (NRW) — which includes leakage and theft — remained between 51% and 53% of total supply during the audit period.
The Comptroller and Auditor General of India estimated that the financial loss due to NRW exceeded ₹4,988 crore.