The development came to light as a part of the report based on a study of samples collected by the Indian Council of Medical Research (ICMR) between 11 and 22 May 2020.
However, senior officials of the BMC said that there is no risk to human beings.
The Covid-19 outbreak has been rampant in Mumbai since the end of March. Against this backdrop, ICMR collected sewage samples from six areas of Mumbai – Dharavi, Kurla, Shivajinagar, Malad, Kanjurmarg, and Wadala between May 11 to 22 and classified them scientifically.
However, no such virus traces were found in samples collected in March.
The officials said that the virus found in sewage doesn’t come into direct contact with humans, since sewage goes into the sea unprocessed.
The civic body also said that there is no such danger to the employees involved in the work of the sewage treatment plant.
Meanwhile, Mumbai city on Tuesday reported 521 new cases, taking its caseload to 2.91 lakh while its death toll rose by seven to 10,991.