Cork was the county with the highest number of registered domestic waste water treatment systems (septic tanks) at 56,281 in 2023, according to the Central Statistics Office (CSO).
The Domestic Waste Water Treatment Systems 2023 report published today (Wednesday, May 22) shows that the number of registered septic tanks in Ireland increased by 1.1% to 492,359 last year.
The seven counties of Cork, Galway, Kerry, Donegal, Mayo, Tipperary, and Wexford accounted for just over half of all registrations.
The data shows that home owners accounted for 97% of all registered waste water treatment systems, while public authorities and other non-domestic owners accounted for 1.5% each.
In Longford, public authorities accounted for 4% of all owners in 2023, compared with Kildare where they accounted for 0.1%
Septic tanks
Linh Nolan, statistician in the environment division of the CSO, said that the data provides an insight into the registration of systems which collect, treat, and discharge waste water from households that are not connected to public sewer systems.
“The number of registrations increased in every local authority in 2023, with Leitrim and Wexford recording the highest annual increase of approximately 2% each.
“In 2023, with 56,281 registered domestic waste water treatment systems, Cork had the highest proportion of systems at 11% followed by Galway (9%) and Kerry (7%).
“Donegal, Mayo, and Tipperary had the next highest proportion of registrations at 6% each, followed by Wexford at 5%,” she said.
Nolan said that there were 5,457 new systems registered in 2023, which was a 4% decrease compared with 2022.
“Cork also accounted for the highest proportion of new registrations in 2023 at 12%, followed by Galway (9%), Wexford and Donegal (7% each),” she said.