Over half of septic tanks inspected last year failed the test, putting householders’ health and the environment at risk, the Environmental Protection Agency (EPA) warns in its latest report on domestic wastewater treatment systems.
Local authorities completed 1,390 inspections in 2024, targeting those near rivers and household drinking water wells at risk of contamination by faulty septic tanks.
There are almost 500,000 septic tanks countrywide used to treat sewage, most of which are in rural areas and attached to individual houses.
Of septic tanks inspected, 56 per cent (773) failed “because they were not built or maintained properly”. When tanks fail inspection, local authorities issue advisory notices to householders setting out what is required to remedy the problem.
The biggest failure rates were in Laois (97 per cent), Westmeath (92 per cent), Roscommon (85 per cent), Kildare (83 per cent), Leitrim (75 per cent), Offaly (70 per cent) and Wexford (70 per cent). There was a 100 per cent failure rate in Dún Laoghaire-Rathdown and a 75 per cent rate in South Dublin, but only seven and four septic tanks were inspected, respectively.
The EPA report found 82 per cent of septic tanks that failed during 2013-2024 were fixed, up from 75 per cent at the end of 2021. This has been aided by increased uptake in grants.
The number of advisory notices open more than two years fell for the first time; from 576 at the end of 2023 to 523 at the end of 2024.
Director of the EPA’s Office of Radiation Protection and Environmental Monitoring Micheál Lehane said: “The reduction of old advisory notices [over two years] is to be welcomed. However, the number not resolved remains unacceptably high, allowing risks to public health and the environment to continue.”
Grant schemes for the remediation of septic tanks were increased from €5,000 to €12,000 last year and the requirement to have registered the septic tank in 2013 was removed. There were 265 grants awarded in 2024, totalling nearly €2.5 million – up from 194 grants in 2023.
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EPA programme manager Noel Byrne said the high failure rate “is a real concern”.
“By maintaining their septic tank and fixing any problems identified, householders will protect their health and the environment. Householders should take advantage of the enhanced grants where applicable,” he said.
Leaking septic tanks can contaminate household drinking wells with harmful bacteria and viruses, while people may be exposed to wastewater if it surfaces in gardens or runs off into ditches and streams.
The EPA’s national inspection plan requires local authorities to complete a minimum of 1,200 inspections annually, targeted near where there are important water sources.
Last year, there was a shortfall in inspections by four local authorities: Limerick, Donegal, Wexford and Leitrim and these need to be completed in 2025, said the EPA.
