Almost 50 wastewater treatment plans across Donegal, Sligo and Leitrim, are part of a new €2.7m monitoring and sampling project.
The aim of the project is to give better protection to river and coastal waters by improving the workings of treatment plants as well as enabling quicker reaction to events such as storms.
Irish Water says it will also allow it identify where investment is needed for future development of towns and villages.
Twenty-five plants in Donegal are part of the project as are about 12 each in Sligo and Leitrim.
John McElwaine, of Irish Water, says the utilituy currently collects wastewater from more than 1,000 separate communities throughout the country.
It treats about 1.6 billion billion litres of wastewater daily before safely discharging it back into rivers, harbours and coastal areas.