PREVIEW

Horley Sewage Works in Surrey has been spewing overflows of untreated sewage containing harmful bacteria just metres away from residential housing and a children’s playground, according to locals.

River Mole River Watch has been investigating the sewage works for months, after trustee, Simon Collins, discovered sewage overflow when on a dog walk next to the works.
Collins stated, “It is an insidious repeating horrible thing.”

The public pathway which surrounds the site is, “Off the scale in phosphate readings,” according to Collins.

According to Collins, the Environment Agency has deemed the overflows as “totally unacceptable” but are yet to sort out the ongoing issue.

The campaigner said, “This has happened repeatedly ... (but) short-term mitigation hasn’t happened.”

He explained the seemingly long-term incident may have been the cause of illness among members of the public, as well as the death of three cows belonging to a local farmer.
While it cannot be proven definitively that the deceased cows and illness were caused by the untreated sewage, Collins claimed the river contained high levels of phosphate, cyanobacteria, sewage fungus, and algal bloom.

The River Mole runs through Horley, Crawley, under Gatwick airport, and even enters the Thames River near to Hampton Court Palace, among other places.
Upon visiting the sewage works, Collins said, “(It) just shouted no investment.”

He added, “They (the Environment Agency and Thames Water) did not respond quick enough ... It has been difficult to build up a dialogue with them, because they say, ‘it’s an ongoing investigation’.”

The Environment Agency rated the incident at a ‘level 4’ which Collins explained as, “no impact.”

River Mole River Watch believes the reality, is a ‘level 3’, potentially a ‘level 2’, which is more reflective of the impact to the public in the area.

The sewage works, which is unmanned, has been under investigation by the River Mole River Watch since November 2023, when they first became aware of the situation.

However, they believe incidents of “gross sewage debris on the land” had been occurring for a while before then and had caused a “lake of untreated sewage effluent” to form.

Despite the recent rough weather, Collins noted that it only requires 15mm-20mm of rainfall to cause a problem.

Testing conducted by River Mole River Watch is still ongoing and includes a test for the harmful bacteria, E. coli.

An Environment Agency spokesperson said: “We are aware of the ongoing situation at Horley Sewage Treatment Works which is completely unacceptable. We have recorded non-compliance against Thames Water for breaching their permit, and our officers are actively investigating this incident. We have also made clear that we require the water company to complete the previously recommended major infrastructure works for this site.”