In 2025, 59% of septic tanks failed inspection, according to the Environmental Protection Agency’s (EPA) report on domestic waste water treatment system inspections 2025.

In 2025, local authorities carried out 1,466 septic tank inspections, of which 863 failed as they were not built or maintained properly.

Faulty septic tanks can pose a risk to human health due to contamination of drinking water wells with harmful bacteria and viruses and it can also cause pollution to waterways by the release of nutrients such as nitrogen and phosphorus.

ADVERTISEMENT

Reasons for failure include operational issues such as inadequate desludging and maintenance, as well as structural defects including illegal discharges to ditches or streams, leaks, ponding and rainwater ingress.

Failed inspections

If a septic tank fails an inspection, the local authority issues an advisory notice to the householder setting out what is required to fix the issue.

These inspections are targeted towards areas identified as a pollution risk, for example near rivers known to be at risk from septic tanks and in areas where tanks are co-located with household drinking water wells.

Since 2013, 7,212 septic tanks have failed inspections and 84% of these tanks had been fixed by the end of 2025, according to the EPA.

The number of failed tanks with advisory notices unresolved for two years or more fell from 523 in 2024 to 442 in 2025.

The national inspection plan requires local authorities to complete a minimum of 1,200 inspections annually. About 14,500 inspections have been completed in its 13 years of running to date.

However, three local authorities fell short in the number of inspections they carried out in 2025, including Donegal, Fingal and Wexford. This must be made up in 2026, as well as planned inspections.

Grants

In 2024, grant schemes for fixing septic tanks increased from €5,000 to €12,000.

There were 460 grants awarded in 2025, totalling nearly €4.77m, up from 265 grants awarded in 2024.

“In 2025, 59% of inspected septic tanks failed. This is a worrying statistic, as many homeowners may be exposing their families to health risks from contaminated private wells, or polluting local rivers, often without realising it,” EPA programme manager Noel Byrne said.

“Regular checks and routine maintenance of septic tanks by homeowners can prevent minor issues becoming major problems, helping to protect their family’s health and the environment.

“Where eligible, homeowners should also make use of grant support of up to €12,000 to remediate faulty systems.”

Too many faulty septic tank systems remain to pose a risk and local authorities will be required to ensure that septic tanks that fail inspection are fixed by homeowners in an appropriate timeframe, the EPA said.