HUNDREDS of tap water supplies and landfills continue to threaten public health.
As many as 269 council drinking water treatment plants remain substandard, with serious health implications.
And 27 rivers are heavily polluted, warned the Environmental Protection Agency (EPA) in its end-of-year statement published yesterday.
A number of landfills also continue to cause "considerable concern".
One of those being investigated is the controversial dump at Kerdiffstown, Naas, Co Kildare, where more than 50 million litres of toxic waste are leaking into water annually.
An EPA-commissioned report, which was referred to in the statement, has previously warned of the the prospect of a catastrophic explosion from gases leaking from this dump.
Two fires have already occurred at the 50-acre dump which had been run by Neiphin Trading, operating as A1 Waste.
The report, which was carried out by SKM Enviros consultants, also warns about the risk of landfill gas to a nearby holiday home for elderly people which is run by the Society of St Vincent de Paul (SVP).
However, the EPA yesterday said a recent assessment identified this as a "low risk".
The Society of St Vincent de Paul said it had complained for many years about the nuisance caused by odour, noise and dust from the Kerdiffstown landfill.
"Our concern has been for the comfort and well-being of the guests, staff and volunteers in Kerdiffstown House."
The SVP added: "We co-operated with the EPA during its recent investigation and we will study the implications of its report.
We are particularly concerned at the uncertainty over the ownership of the landfill."
In its statement yesterday, the EPA said: "The management of a handful of landfills continue to cause us considerable concern. These particular sites have had a considerable impact on local neighbourhoods and resulted in understandable community distress."
Three-quarters of a million tonnes of biodegradeable municipal waste will have to be diverted away from landfills if Ireland is to meet its EU waste targets, the report added.
The EPA also revealed that 269 water treatment plants have to be upgraded to protect public health.
A total of 27 rivers are still classified as seriously polluted.
Some 15pc of groundwater, from which much drinking water is taken, is polluted by phosphates from sewage treatment plants or agriculture.
The poorest performers for bathing water between 2007-2010 were: Clifden, Co Galway; Balbriggan in Fingal, Co Dublin; and Lilliput, Lough Ennel, Co Westmeath.