Householders told to boil water

The risk to people's health is considered to be low

Thousands of people have been warned to boil tap water before drinking it after rain water leaked into a supply tank.

Sutton and East Surrey Water issued the warning shortly before 0500 BST to all households and businesses within its Sutton supply area.

About 80,000 properties and 200,000 people are affected.

The warning comes after torrential rain flooded the company's Cheam treatment works and rain water entered a holding tank used for treated water.

A spokesman said this water went into supply before it was detected, when the works was immediately shut down.

The water tank involved holds heavily chlorinated water as part of the final treatment process. It is designed to automatically eliminate most organisms which may affect water quality.

Medical advice

Mike Hegarty, Sutton and East Surrey Water's operations director, said: "We have reason to believe that some of the water which went into supply may not have met our quality standards and, as a precaution, we are asking everyone in the affected area to boil their water before consuming it until further notice.

"The water is perfectly safe to use for other purposes, including washing, bathing and toilet flushing."

Dr Paul Crook, public health consultant of the south west London Health Protection Unit, said: "The HPA considers the risk to people's health to be low.

"If anyone were to be taken ill they should seek medical advice as normal, via NHS Direct or their local doctor."

The affected area is bounded by Morden, Worcester Park, Carshalton, Wallington, Ewell, Stoneleigh, Sutton and Cheam.