‘No miracle, water turns sweet during monsoon’

Quoting WHO and BMC standards, he said the samples of water collected from Mahim and Dadar were indeed low in salinity, but definitely not potable. ‘‘We appeal to citizens to not consume this water as it is nowhere near the standards of the water supplied by the BMC,’’ said Joseph.

By Saturday evening, the water had started turning saline again.

‘‘When we got the call (from the Mahim police around 5.30 today), we had no doubt what it could be. But we had to investigate,’’ said Dr Shankar Gajbhiye, deputy director, NIO.

The apparent change in taste was noticed probably around low tide as water from Mithi river or rain water flowed into the sea. River water, lower in density, floats on sea water for a while before merging with it.

BMC officials said since Mahim creek is a semi-enclosed area like a natural harbour, dilution of seawater is greater during low tide. Also, the newly-widened Mithi brings to the creek over a third of the city’s monsoon runoff.

‘‘This kind of phenomenon can be experienced all along the east coast at the mouth of rivers like Ganga and Yamuna when they meet Bay of Bengal,’’ Dr Gajbhiye said.