The Environmental Protection Agency (EPA) has asked every local authority to supply it with information on all local water supplies that are at risk from contamination by the cryptosporidium bug.
In the wake of the drinking water crisis in Galway due to contamination with the bug, the EPA wrote last week to every local authority requesting the information. The agency sought details of any public water supplies where there is only chlorination and minimal filtering. These supplies are generally seen as being at high or very high risk of contamination from cryptosporidium.
The agency also asked councils to begin "immediate" monitoring of high-risk water supplies if no short-term measures could be introduced, as this was the time of the year when cryptosporidium levels peaked.
The EPA has also carried out inspections of three sewage plants in Co Galway whose waste water flows into Lough Corrib.
It comes amid increasing speculation that one of the three plants, at Oughterard, is a major source of the outbreak. The plant is unable to cope with the levels of waste in the area because of high levels of development.
Speculation has been added to by the fact that of 25 detailed tests in relation to people who have fallen ill from cryptosporidium in Galway, 19 have indicated infection from a form of the bug usually found in human waste. However, a HSE spokeswoman said there was insufficient data from the tests to draw any conclusion.
In a statement yesterday the EPA said it was unlikely that the plant was the single source of the outbreak, but that such facilities were likely to have contributed to the problem.
"Lough Corrib is subject to pressures from urban waste-water discharges, septic tanks and agricultural run-off, all of which are likely to contain the cryptosporidium parasite and therefore present a risk to drinking water supply," the statement said.
Green Party Mayor of Galway Niall Ó Brolcháin said the Corrib had been "treated like a sewer for years". "Oughterard's waste treatment plant was built in 1947 and designed for a maximum of 250 homes," he said. "There are now nearly 800 houses attached to it."
He also criticised the fact that a new treatment plant was planned for Oughterard but had been delayed because of issues regarding funding between Galway County Council and the Department of the Environment.
The EPA also criticised the failure of authorities to ensure that adequate public-water and waste-treatment facilities were in place before large developments were allowed to proceed.
"The pace of development needs to be brought into line with the capacity for provision of both drinking water and waste-water treatment," the statement added.
"New development should only be allowed to proceed where adequate waste-water treatment and drinking water supply infrastructure is either in place or being put in place in tandem with the development. Otherwise, we are compromising our ability to provide consistently safe drinking water to consumers and our ability to treat waste water to a satisfactory level."