The Hampstead Heath bathing ponds remain closed following concerns over possible contamination of the water during flash floods on Monday.

Samples from the ponds are being tested by Public Health England to assess the water quality, and an incident has been reported to Thames Water and the Environment Agency.

In an email sent to swimmers on Thursday (July 14), the City of London Corporation (CoLC) said: “We will re-open the Bathing Ponds as soon as it is safe to do so for staff and swimmers.

“Further updates on re-opening will be sent to ticketholders as soon as we know more.

“We ask everyone to please consider the quantity of enquiries we are currently receiving and avoid asking for individual updates on when we are likely to re-open.”

Mary Powell, vice-chair of the Kenwood Ladies' Pond Association, said: “The rain on Monday was exceptionally heavy, although it is surprising how much that seems to have overwhelmed the bathing ponds, given the extensive work on the Heath dams in 2015/16."

Mary added: "Infrastructure maintained by both the City of London and Thames Water does not appear to have coped well on 12 July.”

Parliament Hill Lido remains open. Last year the bathing ponds were closed due to unsafe levels of bacteria in the water.

The Ham&High understands Thames Water believes there is no evidence of sewage contamination, but tests for bacteria including E.Coli are ongoing.

A spokesperson for the City of London Corporation said: “Following the heavy rainfall on 12 July the Bathing Ponds have been temporarily closed as the water levels have continued to rise.

“Water quality has also been impacted by storm water and foul water sewers surcharging in the vicinity of the Bathing Ponds.

“Water samples have been collected for testing. It takes up to 48 hours for the full test results to be issued. The test results from Tuesday 13 July confirm the water quality is currently unsatisfactory for bathing.

“Testing will continue until the water quality meets the Environment Agency Inland Bathing Water classification, enabling the Bathing Ponds to reopen.

“We are seeking to accommodate swimmers from the Bathing Ponds at the Lido, which remains open as usual.

“It was reassuring to see the dry dam in operation holding back storm water flowing down the Hampstead Chain of Ponds, and the Model Boating Pond holding the additional flows coming down the Highgate Chain of Ponds – proving the importance of our work to improve the dams over recent years.

“We are continuing to clean and repair damage following the storm and working to ensure the Bathing Ponds can reopen as soon as it is safe to do so.”

The Environment Agency has been contacted for comment.