A LEADING health expert has demanded a public debate over the spread of water disease as fears grow that part of East Lancashire's water supply could soon be infected.

The North West's Director of Public Health, Professor John Ashton, made his call as the NHS revealed health authorities are bracing themselves for a spring outbreak of cryptosporidium carried in water from the Thirlmere reservoir in the Lake District.

The moves comes less than a year after 50 people were struck down in the Ribble Valley by cryptosporidium after animal faeces, which carry the disease, polluted Grindleton Springs. People in around 10,000 homes had to boil water and 50 people were struck down with the illness after it crept into water supplies feeding Chorley, Leyland and South Ribble areas.

The bug causes diarrhoea, headaches, fever, cramps and nausea and, according to the NHS Executive in the North West, several hundred people supplied with water in the Thirlmere Reservoir contract the illness every year.

It is believed the disease enters the water as it passes through a 100-mile long underground aqueduct from Grasmere to Lancashire under grazing land. Professor Ashton today called on the public to start demanding answers from firms like North West Water.

He said: "The privatised water companies claim to be doing everything they can to tackle the problem but here in the north West their expensive improvement programme will take up to four years to complete.

"In the meantime, people will continue to become ill. We need to ask ourselves whether the companies and public health professionals are doing their best. Is there more that can be done? In the aftermath of the Hatfield rail disaster, the public has started to ask this question of all former public bodies."

It is a view shared by Liverpool John Moores University lecture Mary Lyons, who has written a bulletin on cryptosporidium on the internet. She said: "It is easier to find out about water quality in Sydney, than it is to find out about water coming from our own taps.

A spokesman for North West Water said: "Thirlmere reservoir supplies some areas within the Blackburn postcode. We are aware of the report and looking into it."

Ribble Valley MP Nigel Evans said the reaction of North West Water -- which issued £5 goodwill discounts to affected people -- was totally inadequate.