Thousands of people were warned to boil drinking water today after a contamination scare.
Anglian Water issued the warning after cryptosporidium was found in samples in Northamptonshire. It is thought the affected area covers 108,000 properties and 250,000 people.
Cryptosporidium is naturally occurring but can cause severe stomach upsets, especially in young or elderly people.
An Anglian Water spokesman said: "We do about one thousand samples every day just testing on water quality and last night we had traces of cryptosporidium.
"It's a naturally occurring bacteria but if it gets into the human body it can cause quite severe stomach upsets. It's something we do not take any risks with whatsoever.
"When the second test came back confirming it we immediately let everybody know.
"We have asked 108,000 properties, equivalent to 250,000 customers, to boil their water. If they boil it, it eliminates the bacteria."
The spokesman said all water should be boiled, including for use when brushing teeth and giving to pets.
He said: "Bottles of water were being handed out to vulnerable customers."
He added: "Until we know exactly why this had happened we can't say when it's going to end. It's more likely to stretch into weeks rather than days."