Two thirds of domestic septic tanks in Wexford failed inspections last year – while over half of those tested nationally failed.
The Environmental Protection Agency says 23% were a risk to human health or the environment.
Six local authority areas had failure rates of above 75%, while Wexford’s failure rate in 2020 was 66%.
Noel Byrne, from the EPA, says there were two main reasons for failures.
“One is around construction which can be very simply things like leaks or maybe a pipe going from the septic tank is going into a nearby watercourse.
“And the other is maintenance and its pretty much 50:50 of those issues.
“Roughly 60% of failure rate has been found by local authorities when they conduct the inspections.
“An area of particular concern are people who have a drinking water well on the same site as their septic tank.
“There are 166,000 households in Ireland who have a drinking water well and a septic tank on the same site.
“If your septic tank is not working properly, you could contaminate your well, it could contaminate your neighbours well with parasites and viruses that would ultimately make you ill.”