The water company at the centre of a poisoning outbreak that may cost millions of pounds was warned last year of the need to inspect a treatment works thought to be the source of a similar incident in 1992.
South West Water was warned that the works, the probable source of a micro-organism that has infected at least 388 people in south Devon, needed a detailed inspection to prevent a further outbreak.
In a report following an outbreak of the cryptosporidium micro-organism three years ago, Dr Mark Kealy, then consultant in communicable disease control at Plymouth and Torbay health authority, called for an independent expert to look at the treatment process at the Littlehempston works.
His request was refused by South West Water. In a damning conclusion to his report, he said such a decision was "inexcusable" and added: "If South West Water have nothing to hide then there is no reason why they should not allow an independent water treatment scientist to look round the works to reassure us. Owing to the unwillingness of SWW to be open about their processes, it is difficult to be confident about the security of the water supply."
Mr Kealy said SWW representatives had no criticisms of substance about his report but "tried to cast aspersions on the 'scientific' quality of the report and made comments that were pedantic in the extreme".
The latest outbreak was first identified on 11 August and 200,000 households are still being forced to boil their water in the Torbay, South Hams and Teignbridge area. Children at 80 schools in the area who started the new term this week received bottled water.
SWW has already agreed to an ex-gratia payment of pounds 15 to customers - a total bill of pounds 1.5m - and legal claims are mounting from those struck down by the disease and hoteliers and campsite owners who fear a catastrophic effect on trade. The final bill could be millions of pounds. Mark Hann, South-west regional manager for the water regulator Ofwat, said pounds 3mo f improvement works were scheduled to be completed at the Littlehempston works by 2000, to reduce the danger of cryptosporidium infection.
He believes the recent outbreak will spur water companies to act more quickly. "The liability for causing a public health risk means companies face limitless damages. These pounds 3m works could already have been half paid for by the pounds 1.5m payments to customers."
Because of the previous outbreak and the criticism of SWW in not accepting that the cause of water that they supplied, Dr Sarah Harrison, consultant in communicable disease control at Plymouth and South West Health Trust, said stringent procedures were in place to identify cryptosporidium.
"This has been a much bigger, more rapid outbreak than the last time, but at the same water treatment works," she said. "When we plotted the outbreaks on a map they closely corresponded with the boundary of the works."
Yesterday, SWW officials still maintained that it was too early to speculate on the source of the incident and said a major investigation was under way. The instruction that all water should be boiled was a "precaution".
A spokesman said the micro- organism was a relatively new discovery and what was at issue was "frontier of science stuff".
He denied that the water company was now diverting water whose source was known to be free of the micro-organism to the works to ensure negative testing, but this was contradicted by Dr Harrison.