Residents in parts of Surrey and south London have been told they could face a complete loss of water supply after a major fault at a water company’s treatment works.

Sutton and East Surrey (SES) Water said its customers around Sutton, Morden and Epsom could be affected as it carried out “essential repairs” on Monday.

Two bottled water stations have been set up at Bourne Hall in Ewell, Surrey, and in Upper High Street Car Park in Epsom, as a makeshift solution, while the issues at its Cheam Water Treatment Works were resolved.

Both stations will remain open throughout the night and into Tuesday.

The company had earlier said that parts of Carshalton, Cheam, North Cheam, Wallington, Hackbridge, Worcester Park, Ewell and South Croydon may also have experienced issues with their water supply.

Luke Taylor, Lib Dem MP for Sutton and Cheam, said on X, formerly Twitter, that the situation was “not good enough” and he would be monitoring the situation closely.

He said: “I have been informed by SES this afternoon of a fault at the Cheam Water Treatment Works.

“Despite efforts by SES teams to repair a critical valve failure and sustain the water supply through alternative measures, they have been unable to fully resolve the fault.

“Unfortunately, this means the supply across the network has diminished, and some customers may now experience interruptions to their water supply, including complete loss of service.”

Mr Taylor added: “I have contacted SES to tell them that this is not good enough for residents in Sutton and Cheam and that addition water stations must be set up closer to local residents.”

SES Water confirmed it was working closely with St Helier Hospital in Sutton to support their water needs, he said.

The company said it would be looking to set up further bottled water stations on Tuesday.

An SES Water spokesman said: “Following a fault identified overnight at our Cheam Water Treatment works our teams initiated a routine alternative supply plan to ensure customers water supply operated as normal.

“Unfortunately, our reserve levels as part of this response have not been able to maintain the supply and demand, meaning a number of customers within Sutton, Morden and Epsom are currently experiencing no water supply until this fault is fixed.

“We are therefore standing up an emergency response ensuring all partners and stakeholders are supported as well as our priority service customers.

“We sincerely apologise to all customers who are impacted by this disruption.

“Please rest assured that this is our absolute priority to restore supplies to these areas as fast as possible and we will be communicating updates via our social media channels and our website.”

SES Water supplies 160 million litres of water to more than 750,000 people in parts of Surrey, Kent and south London each day, according to the company’s website.

Pennon, which also owns South West Water, Bristol Water and Bournemouth Water, was cleared to buy the company for £350 million in June.