The report, submitted by a commission to the Supreme Court of Pakistan, said 83.5 per cent of water in 14 out of 29 districts of Sindh is unsafe for drinking, Dawn reported on Monday.
The commission was constituted last year when a number of Sindh residents filed petitions in the apex court against government offices which "are required to ensure provisions of potable water, sanitation and hygienic atmosphere, but they have individually and collectively failed to discharge such fiduciary, statutory and constitutional duty".
The water supplied to the residents has "insects crawling in it, despite sieving it through the thinnest of muslin", Mohammad Riaz, a chauffeur who lives in one of Karachi's squatter colonies, told Dawn.
"Often the water tasted salty, or was cloudy," added another resident who in January switched to bottled water.
Head of the commission Justice Muhammad Iqbal Kalhoro earlier in July "asked the head of the Karachi Water and Sanitation Board, responsible for 90 per cent of water supply in the metropolis, to show him one area which was supplied with clean water", said Ghulam Murtaza, amicus curiae for the commission.
The commission was tasked to collect water samples from 14 cities as villages were left out because the taskforce only looked into major urban centres where water was supplied by government agencies.
A research officer of the Pakistan Council of Research in Water Resources (PCRWR) said that out of 460 samples collected from across Sindh, 232 (50.4 per cent) were collected from surface water, 179 (39 per cent) from groundwater, 46 (10 per cent) from reverse osmosis filtration plants and three (0.6 per cent) from mixed sources.
Murtaza said the analysis suggested that Karachi had the highest water supply contamination score. At least 90.7 per cent samples collected from various places in Karachi were unsafe for drinking purposes.
"The presence of E. coli indicated the mixing of sewerage and drinking water supplies," said Murtaza.
Karachi gets its water from the Keenjhar lake -- sourced from the Indus -- nearly 122 km from the city, through a canal system.
"The first drop of water that reaches Keenjhar lake from the Indus takes 17 days to travel to Karachi," said Khan, emphasising the value of the water.
Karachi Water and Sanitation Board has blamed the residents for the "contamination" as they "steal" water like electricity.
"When electricity is stolen, you can take action. When water is stolen from the mainlines which are underground and are punctured, you cannot," he said.
The Board suggested that people played their civic part by keeping their underground water storages clean. "How often do we hear of residents of high rises, mosques and hospitals getting their tanks cleaned?"
Another water board official, requesting anonymity, said: "The board repairs leaks, and even replaces pipes every now and then, but while a complete rehabilitation of the entire distribution network is needed, it is a huge undertaking and may require two-to-three years."
Karachi has six water treatment plants (under the KWSB) that do not work optimally.
When Justice Kalhoro visited the treatment plants, the Board admitted that "200 MGD is supplied unfiltered owing to a lack of capacity".
With unrestrained demand from Karachi's galloping population, the water board is expanding the supply system, while failing to rehabilitate the existing one. An official said "there is still a shortfall of 50 per cent".
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)