The Environmental Protection Agency (EPA) plans to step up septic tank inspections in high-risk areas. Checks on domestic treatment systems will be increased in Louth, Meath, Cavan, Galway, Clare and Cork amid concerns that tanks are polluting water sources.
While around half of all tanks inspected so far are not operating properly, the EPA says that most tanks are structurally sound, but require better maintenance, including de-sludging.
The EPA said that inspections would be targeted in high-risk areas, which would include places with a large number of tanks installed and where there were concerns about groundwater being contaminated.
Geological conditions would also be taken into account. For example, a shallow depth of soil means it is easier for effluent to enter groundwater, while a lack of drainage means that waste appears on the surface or enters rivers, posing a risk to public health.
The increase in inspections comes after 1,000 tanks were assessed over the past year by inspectors working on behalf of the EPA.
Not until October will a final analysis be available, but the most recent figures suggest around half of systems fail, generally because they are not properly maintained.
There are some 500,000 septic tanks across the country and half of all inspections are carried out in high-risk areas. This number is expected to increase, especially where drinking water is abstracted or where the fresh water pearl mussel is found.