Water supplier Thames Water said it has collected samples last week where traces of E coli showed up at one property.
Although surrounding Brockley homes have been tested and there is no indication of further traces, Thames Water has advised that households boil all water as a precaution.
The Guardian reports that a notice has been sent reading: “The samples we have recently collected from your drinking water tap were not of the quality we would normally expect.
“We are investigating whether this may be due to an issue with our mains supply or whether this is related to your internal pipework or fittings.
“As a precaution we therefore advise you to boil all water before it is used for drinking, cleaning teeth, preparing food, provision of drinking water for pets.”
According to the paper, Thames Water has also shared advice to bleach taps and sinks after use.
E coli is a bacterial infection which can affect the guts and cause diarrhoea, stomach cramps and fever.
A Thames Water spokesperson told The Guardian: “As part of our standard water quality testing that we carry out throughout the year, last week tests were undertaken at a property where traces of E coli were found.
“We also tested surrounding properties and no further traces were found.
“For the impacted one property – we have issued a boil water notice and have supplied the resident with bottled water while investigations are ongoing.
“Follow-up investigations indicated this is likely due to either contamination of the tap or internal plumbing system.
“We are continuing to engage with the customer providing advice on flushing the taps to bring high-quality water back into the taps.”
