The Bidhannagar Municipal Corporation (BMC) will soon drain water out of the swimming pool where a teenager died on Tuesday and scrub the tiles of the floor and the walls, said an official of the civic body.

The official said the clean-up decision was taken based on members’ feedback that the water turns progressively murky, reducing visibility, as one dives deeper into the pool.

The Bidhannagar Municipal Sports Academy swimming pool, opposite Mayukh Bhavan in Salt Lake, is run by the BMC.

Police on Wednesday said the post-mortem on Elina Dutta Bhattacharyaa was “inconclusive” as the autopsy surgeon did not share any opinion on the cause of death of the 15-year-old.

The death of the Class X student has raised questions about pool maintenance.

IA block resident Subhajit Sarkar, who swims daily at the Bidhannagar Municipal Sports Academy pool, said visibility decreases as one dives deeper.

The police probe till now has not indicated anything that could suggest that poor visibility was a reason for Elina’s death.

“We are probing all possible angles and will verify whether the pool authorities followed the standard protocol,” said a senior officer of the Bidhannagar commissionerate.

Officials of the Indian Life Saving Society, popularly called the Anderson Club, said they strictly follow the protocol while enrolling trainees and for the maintenance of the pool.

“To enrol, one has to produce a certificate issued by a doctor after checking all parameters. One also has to submit a declaration from guardians whether the applicant is allergic to any chemical or has a medical history,” said Ketan Thakkar, the director of swimming at ILSS.

He also stressed the need for proper maintenance of the pool and to have enough trainers, depending on the number of trainees.

“The pH level of the water in our pool is tested three to four times a day to check its acidic level. Also, the chlorine level has to be maintained accurately. We do the backwash every second day and use the best media at the filtration plant,” Thakkar said.

BMC officials said the pool where Elina died is “deep cleaned” every Thursday.

Aratrika Bhattacharjee, the mayoral council member in charge of sports, said the filter media in the pool’s filtration unit was replaced before it was opened this year.

“The pool has a filtration unit that uses multi-graded filter media,” said Bhattacharjee. “The pool’s water quality and pH level are checked once a week.”

She said lifeguards will be posted on high chairs so they can have a clear view of the swimmers and the trainees.

The civic body will reduce the batch size. An official said more than 2,500 members have enrolled this year. “Every batch has around 40-50 swimmers and learners,” the official said.

Gaurab Ghosh, the director of Calcutta Waterworks Infrastructure, which builds swimming pools, said: “Pools of this size need a lot of maintenance to ensure water doesn’t get heavy or murky....”