Faecal content in Mumbai’s seawater 60% higher than accepted standard: Study

Discharge of untreated sewage into the sea by the municipal corporation has caused this, said MPCB officials

Faecal coliform (FC) — an indication of human and animal excreta — in the seawater along Mumbai’s coast is 60% higher than accepted standards, says a study by the Maharashtra Pollution Control Board (MPCB). Reason: Discharge of untreated sewage into the sea by the municipal corporation, said MPCB officials.

Exposure to faecal contamination through swimming in seawater can lead to gastrointestinal illnesses, respiratory infections and irritation of the skin and eye, said doctors

The count of FC — measured as colonies of coliform per 100 millilitre (ml) of water — was as high as 1,600/100 ml against the accepted limit of less than 1,000/100 ml at Mithi River, Girgaum Chowpatty, Worli Sea Face, Malabar Hill and Haji Ali. Before the monsoon season this year, the count was 920/100 ml, the study said.

Along Versova, Juhu, Nariman Point, Dadar, and Gateway of India, the FC levels varied between 920/100 ml to 1,200/100ml. It was 540/ml before monsoon.

Levels at creeks such as Thane and Mahim were much lower at 49/100ml and 63/100ml.

MPCB officials confirmed that the high level of FC in coastal waters was a matter of concern. “We will issue directions to the Brihanmumbai Municipal Corporation (BMC) to carry out disinfection and chlorination of sewage entering directly into the sea. This is the only way to practically reduce the amount of FC and we will ensure this is done at the earliest,” said P Anbalagan, member secretary, MPCB.

Last month, the Union environment ministry imposed stricter pollution norms for industrial and domestic waste at sewage treatment plants (STPs) before releasing it into water bodies. The rules stated that the concentration of FC in sewage needs to be controlled by state pollution control boards and should not exceed 1,000/100ml.

Exposure to faecal contamination through swimming or ingestion can lead to gastrointestinal illnesses, respiratory infections and irritation of the skin and eye, said doctors. Faecal bacteria from the water are transferred to the sand and sediment on beaches.

“Citizens exposed to this water in any manner are at immediate threat of diarrhoeal diseases (passage of three or more loose or liquid stools per day). Contaminated water, especially with the presence of FC, where the specific kind of bacteria is not known is a health risk for residents of the area,” said Dr Paresh Kantharia, surveillance medical officer in World Health Organisation (WHO), Mumbai. “The main remedy is to wash hands with clean water after coming in contact.”

The faecal content notwithstanding, overall water quality improved along many places on the coast after the rains. The Water quality index (WQI) — a single number (grade) that measures overall water quality taking into account pH (acidity levels) dissolved oxygen, biological oxygen demand (BOD) or the concentration of oxygen required for sustaining aquatic life, chemical oxygen demand (COD) — which was reported as ‘polluted’ or ‘bad’ category between January to June improved to ‘non-polluted’ category or ‘medium to good’ for a majority of locations in July, August and September. The improvement in WQI is attributed to monsoon rain that diluted sewage content. WQI levels for Mithi River and Versova Beach were the only two locations falling under the ‘bad’ or ‘polluted’ category.

Anbalagan said the improvement in water quality can be attributed to high level of dilution at marine outfalls during the monsoon months. “The other reason is that common effluent treatment plants (CETPs) are performing well with a few exceptions like Tarapur and Taloja, which are treating all effluents before discharge at creeks,” said Anbalagan. He said with the new discharge standards in place, the BMC needs to expedite the setting up of new STPs with primary screening of chemicals followed by secondary biological treatment through multiple technologies. “They [BMC] have been informed,” said Anabalagan. “There cannot be any excuses now from their side.”