Quarter of septic tanks inspected pose risk to human health or environment

There are nearly 500,000 septic tank systems in Ireland, which are used predominantly by rural householders in order to treat sewage. 

More than half of Irish septic tanks failed inspection last year, while almost a quarter of those inspected posed a risk to human health or the environment, according to the Environmental Protection Agency (EPA).

There are nearly 500,000 such septic tank systems in Ireland, which are used predominantly by rural householders in order to treat sewage. 

The EPA said that of 809 inspections of septic tanks and other domestic wastewater treatment systems in 2020, some 433 of the systems, or 54%, failed inspection because they were not built or maintained properly. 

Inspection failure rates

In Cork, there was a failure rate of 54% out of 59 inspections last year, while 88% of the 352 failing systems since 2013 have been fixed. 

In Clare, 57% of the 30 inspections carried out failed, while 84% of the 150 failures since 2013 have been rectified. Limerick fared better in 2020, with 44% of 36 inspections failing, but dropped to 79% of 194 fixed since 2013.

Just 18% of Waterford systems out of 11 inspections failed in 2020, while there were no data available for Tipperary last year. Kerry had just one inspection, which passed.

Almost 3,000 systems that failed from 2013 to 2020 have been fixed across the country, or 76% overall.

A total of 182 systems nationally, or 23%, inspected in 2020 were a risk to human health or the environment, as faulty systems can contaminate household wells and pollute rivers, the EPA said.

Three-quarters of systems that failed inspection have been fixed, but it remains an area that requires increased engagement and enforcement by local authorities, the body's domestic wastewater treatment report for 2020 said.

Failure to resolve older cases remains a concern, according to inspectors. 

"There were 468 advisory notices open more than two years at the end of 2020. These must be addressed as a matter of priority. The EPA has engaged with local authorities on progressing the resolution of these advisory notices," the report said.

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Six local authorities have taken 34 legal proceedings for failure to fix domestic wastewater treatment systems since the beginning of the current national inspection plan.

Maintenance failures

Some 4,000 inspections are earmarked from 2018 until 2021 under the plan, which saw numbers drop last year due to the impact of the Covid-19 pandemic.

The main reasons for failure were twofold, according to the EPA - de-sludging and maintenance failures; and structural defects causing illegal discharges to ditches and streams, leaks, ponding, and rainwater entry.

Dr Tom Ryan, director of the EPA’s office of environmental enforcement said the onus was on householders with septic tanks to get yearly checks done.

Householders should ensure effluent from their septic tank is not ponding in their garden, going to nearby streams, or contaminating their drinking water well. 

"They should visually check their septic tank and get their well tested at least annually to satisfy themselves that their septic tank is not posing a risk to the health of their families, their neighbours, and the environment," he said.

The septic tank grant scheme, which was expanded in 2020, offers grants of €5,000 to assist in addressing malfunctioning systems, the EPA said.

EPA programme manager Noel Byrne said it is important that householders fix septic tanks where problems are detected.