250,000 people warned to boil tap water for weeks after stomach bug strikes

A quarter of a million people heve been told to boil all drinking water for the next month after samples were found to contain a stomach bug.

Cryptosporidium, which can cause severe illness for weeks, has been found today in tests by Anglian Water.

Around 108,000 homes in Northampton, Daventry and nearby Northamptonshire villages must boil water for cooking, drinking or cleaning teeth.

Vans with loudspeakers were later sent out to warn people about the problem and alerts were given to the media.

Seventeen schools have been forced to close. Northamptonshire council said they should shut if they did not have bottled water.

Some supermarkets rationed bottled water as customers began panic buying and cleared the shelves of stocks.

The water firm is investigating the cause of the contamination at a treatment works near Pitsford reservoir, north of Northampton.

A spokesman said: 'Until we know why this happened we can't say when it's going to end. It's more likely to stretch into weeks rather than days.

'Once we've got to the source, we need to sample. Once we've done that and we are happy, we need to flush the whole system to make sure there is no water left which was affected. So it is a really, really big job.'

The Drinking Water Inspectorate watchdog will also investigate.

The parasite is common in farm and domestic animals, and is passed on through their manure or their corpses.

It is in the environment at low levels all the time, but greater concentrations are common in spring, particularly when heavy rain washes it into the ground, rivers and lakes.

It is usually destroyed during the water treatment process. A spokesman for Anglian Water said: 'We do about 1,000 water quality tests a day.

'Cryptosporidium is 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.'

Boiling water kills the bacteria, which can cause an infection called cryptosporidiosis.

This is most common in children aged up to five but it can affect anyone.

There is no specific treatment. People with weak immune systems are most likely to be seriously affected.

It is not yet known how far into the water supply the bug has travelled. The Health Protection Agency said there were no confirmed cases of cryptosporidium in the area.

It advised anyone with symptoms such as diarrhoea, stomach pains, dehydration, weight loss and fever, to see their GP.

Anglian Water said the bug has an incubation period of five to seven days so it may be up to a week before it is clear if anyone has been infected.

The firm said pets' drinking water should also be boiled but tap water is safe for washing and toilet flushing.

Bottles of water have been handed out to vulnerable customers, such as the disabled, although some who were eligible but not registered for the scheme said they could not get any.

In 2005, 231 people were hit by cryptosporidium in North Wales after an outbreak in the water supply. About 70,000 homes had to boil their water during a two-month period. Dwr Cymru Welsh Water was fined £60,000.