Donegal County Council is urging home owners who have a septic tank to register it before a deadline expired next February.
Donegal has the third highest number of septic tanks in the country only behind Cork and Galway.
New rules announced yesterday oblige homeowners to make sure their tanks are not polluting rivers and lakes - those who refuse to carry out repair works could end up in court.
Central Statistics Office figures show there are almost 500 thousand on-site wastewater treatment systems in the Republic- just over 30 thousand of them are in Donegal.
If you have a septic tank, you have until February the 1st 2013 to register it - inspections will begin next year with local authority officials checking to see if tanks are working properly.
They will have the power to force homeowners to undertake repair works but some financial help may be provided by the Department of the Environment in that regard.
It has been reported that 35,000 homes across the country would be among the first to be inspected because they are believed to pose the greatest risks to water courses.
It can cost up to 250 euro to pump out a septic tank - those who don't could face a fine of up to 5,000 euro.
Donegal County Council is urging people to register their tanks at protect our water dot IE