The Environmental Protection Agency says over 99% of public water supplies in Donegal comply with micro biological and chemical standards.
Hoever, the agency's water quality report for 2011 expresses concern at the poor water quality in many of the country's private wells.
According to the EPA figures, microbiological compliance in Donegal's public schemes fell by .3 of a percent to 99.5% in 2011. Chemical compliance figures remained unchanged at 99.4%.
The main problem was in Ballintra, where the county's only boil notice of the year was implemented in May and lasted six days. However, by year's end, Ballintra was one of three supplies taken off the EPA's remedial action list.
There are currenty 14 schemes on that list. They are Ballyshannon, Burnfoot, Cashilard, Creeslough, Donegal River Eske, Fintown, Glenties - Ardara, Gortahork - Falcarragh, Greencastle, Owenteskna - Kilcar, Letterkenny, Portnoo - Narin, Rathmullan and Rosbeg.
All those works shyould be complete by the end of September next year according to the EPA.
Meanwhile, the agency says it's concerned at the poor water quality in many of the country's private wells.
Tests show levels of VTEC - a harmful strain of E.coli that could lead to kidney failure - have doubled in private wells, in the last year.
They are calling on all owners of wells and those not on a public water supply to check their water source.