The water along the Worli and Bandra shoreline in the city has a high bacteria count, a latest civic environment report found. According to the Brihanmumbai Municipal Corporation’s Environment Status Report 2015-16, levels of Escherichia Coli (E Coli) — bacteria found in the environment, foods, and intestines of people and animals that could lead to diseases — was found to be three times the safety limit at Worli and much above permissible limits at Bandra.
The study was carried out at three marine outfall locations in Mumbai – Worli, Bandra and Colaba — by BMC’s Sewerage Operations department at their laboratory in Dadar between April 2015 and March 2016. The safety limit for E Coli is 100 millilitre (ml), but at Worli it was found to be at a maximum of 320ml and 130ml at Bandra. However, levels were below permissible limits at Colaba at 90ml.
Additionally, the study also found high bacteria content through most probable number (MPN) test to be eight times the safety limit at Worli, more than five times at Bandra and twice the safety limit at Colaba. The MPN test identifies the total amount of bacteria content in any water body.
“While the water being released in all three marine outfalls in the city is being treated by the corporation, the presence of a large number of slums near Worli and Bandra have led to high E Coli levels,” said a senior civic official from the sewerage operations department. “Untreated waste dumped at sewer lines along with open defecation by slum dwellers has led to the problem. However, Colaba hardly any slums near to the marine outfall site.”
Officials from the Central Pollution Control Board (CPCB) said the presence of high bacteria content in coastal sea water can affect public health. “While an E Coli level faecal coliform , a bacterium found in human and animal faeces, of 300ml and above does not affect marine life much but it definitely affects the surrounding areas of the water body as the area can become a storehouse for many water-borne diseases,” said A Sudhakar, additional director, Central Pollution Control Board.
He added that sewage needs to be collected at a common point and then treated before it is discharged into the water body.
Officials from the National Institute of Oceanography (NIO) said diseases are likely to be transmitted when there is consumption of fish from these polluted areas.
“As per the figures from the BMC’s report, there are high levels of contamination along the coastline, which cannot be assimilated by coastal waters. Hence, even if fish consumes the bacteria from the water and people consume it without cooking it properly, the chances of diseases are very high,” said Dr Baban Ingole, chief scientist and professor, NIO, adding that the pollution needs to be treated at source.
“The civic authorities need to immediately treat the polluted water and open defecation should not be permitted,” he added.
Sewerage treatment in Mumbai
The sewage disposal system in Mumbai is divided into seven zones — Colaba, Worli, Bandra, Versova, Malad, Bhandup and Ghatkopar. Sewerage infrastructure consists of 1,636 km of sewers, 25 pumping stations, preliminary treatment facilities and marine outfalls at three locations (Colaba, Worli, Bandra), three-stage aerated lagoons (that help in naturally purifying the water) at Bhandup and single stage lagoons at Versova and Ghatkopar.
In financial year 2016-2017, Rs198.33-crore budget has been proposed for laying new sewer lines in unsewered area and upsizing of existing sewer lines in the city, eastern and western suburbs whenever required.