A major main road connecting Reading, Slough and London is in danger of being flooded with sewage, a councillor has warned.

Hurst councillor Wayne Smith said the eastbound lane on the A4 Bath Road has been ‘flooded in several places’ between Blakes Lane and Castle Royle golf club for most of 2024 due to blocked culverts.

But he warned that, if left, rainwater could overload a nearby Thames Water pumping station at Kiln Green – causing a sewage overflow.

Councillor Smith said: “The blocked culverts cause a domino effect during heavy rainfall which puts the whole sewage and drainage infrastructure under the kind of loads which cause the water companies to discharge raw sewage into our rivers.

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“Without regular maintenance – which has been lacking for several years – the blocked culverts pose a recurring and major threat to health and safety, as well as a danger to motorists.”

He added that imminent housing developments and blocked drainage would cause a ‘perfect storm’ that could have ‘a calamitous effect on the health and safety of residents and road users.’

Wokingham Borough Council, which maintains the culverts, said they were blocked by silt erosion after heavier rain than expected. It said staff would unblock them this week.

Councillor Ian Shenton, responsible for the environment, said: “We have had a very wet winter—the wettest November and one of the wettest Februarys on record, with south England being particularly wet with more than 150% of the 1991 – 2020 average rainfall for this period.

“This has caused us, as well as many of our neighbours, significant problems with flooding and flooding related issues.

“The culverts under the A4 and Blakes Lane are blocked by silt erosion, due to the heavy rains we’ve had. This has caused a complete blockage of the culverts and is causing the ditch to overflow onto the road.”

He added: “Once the work is complete, we will evaluate the culvert network to see if it functions as it should once the blockages in the culverts and the downstream ditches are cleared.”

Thames Water said it did not believe issues at its pumping station had caused flooding. But it confirmed that blocked culverts could cause a station to back up. It did not answer questions about whether it should upgrade the Kiln Green station to cope with increased pressure.

A Thames Water spokesperson said: “Heavy rain can sometimes cause surface-water flooding. Normally excess rainwater is diverted into roadside gullies, which feed into our sewers.

“If the gullies or sewers become blocked, water can back-up and flood a road. The local authority is responsible for drains in the road and the pipes connecting them to our sewer.”