Thames Water checking west London water quality after concerns raised

Image: Library image of a Thames Water van

West Londoners boiling tap water as a precaution

Thames Water, London’s water supplier, is looking into west London’s water quality after concerns were raised about contamination of drinking water.

Dozens of people in the Beckenham area of south-east London reported being unwell with stomach cramps, vomiting and diarrhoea over the weekend. Their symptoms mirrored similar reports coming out of Devon earlier this month, where unsafe drinking water led to more than 100 cases cryptosporidium, a parasite found in faeces which can cause gastrointestinal and respiratory illness.

In response, South West Water, which manages Devon’s water supply, told 17,000 households and businesses in the Brixham area not to use their tap water for drinking without boiling and cooling it first.

On Monday (27 May), Thames Water, which is the UK’s largest water company, said there are “no water quality concerns” following testing in the Central Sydenham water zone – which covers Beckenham.

Nonetheless some residents in Chiswick have told us they are boiling their tap water as a precaution after following the news over the weekend. Seeking to quell fears that water quality could have been compromised locally, Thames Water urged their customers to check local water quality reports online and said that since 2010 “99.5% of tests taken from customers’ taps met the standard required by UK legislation.”

The recent water quality report published on Thames Water’s website for Chiswick & Hammersmith states both areas have “very good quality” water, but this report only covers the period 1 Jan 2023 to 31 December 2023. No up-to-date tests have been published.

After we raised this, Thames Water confirmed to The Chiswick Calendar that they are carrying out checks on water quality in west London.

Image: Frothed-up sewage on the banks of the River Thames pictured at Strand-on-the-Green

Why has cryptosporidium been found in the UK’s water supply?

Cryptosporidium parasites get into surface water sources, such as rivers and lakes, from the faeces of infected animals or people. Public water systems that get their water from these surface water sources can contain Cryptosporidium oocysts (the egg-like form of the parasite).

Public health officials believe that the presence of a few oocysts in drinking water does not pose a threat to people with healthy immune systems. It takes an unusual combination of events to lead to a situation where the drinking water would be considered unhealthy.

A change in the source water and a failure of the treatment system would have to occur at the same time for the drinking water to be considered unhealthy.

Lack of investment in England’s privatised water infrastructure has meant even a drizzle of rain often overwhelms the country’s sewage network, which water companies say necessitates raw and diluted sewage dumps in our rivers, seas and waterways.

In March, figures released by the Environment Agency showed that South West Water, which covers Devon, discharged sewage a staggering 582,49 times in 2023, a 55% rise compared to in 2022.

Similarly, as of March 2024, Thames Water has pumped human waste into the Greater London area of the River Thames for a total of 1,914 hours since the start of 2024 – equivalent to 79 days – according to the campaign group River Action UK.

Such massive dumps of human excrement into the waterways have been blamed for causing potentially lethal increases in bacteria in the Thames, such as E Coli – which is found in faeces.

READ ALSO: Potentially lethal levels of E coli found in River Thames ahead of Boat Race

Image: Library image of a tap 

“No water quality concerns” after testing carried out in south-east London

In a statement released following reports of sickness in south-east London, a Thames Water spokesperson said:

“We understand that, following recent media reports, customers may be worried about their water supply; however we can confirm there are no water quality concerns in the Central Sydenham water zone.

“Our technicians collected samples from a property in the area on Wednesday 22nd May following a customer contacting the business. Initial on site testing carried out by our accredited technician did not indicate an aesthetic issue with the water, further samples were also collected for laboratory analysis and results showed no concerns.

“We carry out regular sampling at the local works, reservoirs and across the whole of our supply area on a routine basis which verify the excellent quality of the drinking water we supply.

“We take the quality of our water extremely seriously – it is the highest quality drinking water in the world – and since 2010 more than 99.95% of tests taken from customers’ taps met the standard required by UK legislation. Every year we carry out more than 500,000 tests, taking samples from source to tap.

“Customers can find information about their water supply by inputting their postcode on our website. Should anyone be concerned about their tap water, we’d encourage them to contact us.”