Skip to main content

Environment, Climate Change & Agriculture

Septic Tanks/Domestic Wastewater Treatment Systems

About one-third of all houses (500,000) in Ireland rely on a domestic wastewater treatment system (DWWTS) to collect, treat and discharge their wastewater. Septic tanks are one type of DWWTS.  

When not designed or operated properly, DWWTSs are in danger of contaminating domestic wells or water sources.  Contaminated water from DWWTSs can carry pathogens (bacteria/germs/bugs) and harmful chemicals that can cause serious illness and damage to the environment. It is the responsibility of the owner of the septic tanks/domestic wastewater treatment systems to maintain them in full working order including regular desludging of the tank.  

An information leaflet on how to look after your septic tank/domestic wastewater treatment system is available HERE.

Desludging of Septic Tanks/Domestic Wastewater Treatment Systems 

A sample list of contractors permitted to empty septic tanks/wastewater treatment systems is available here and a full list is available from the national waste collection permit office  

It is an offence to use an unpermitted person/contractor to empty your septic tank. 

Information for farmers on how to safely spread sludge from their own tanks on their own land is available HERE 


Mayo County Council carry out inspections each year of septic tanks under the EPA National Inspection Programme. An information leaflet on what to expect from a septic tank inspection is available HERE.   

Grant Schemes

A number of grant schemes are in place for necessary upgrades of septic tanks/domestic waste water treatment systems. Find out more here.

Grant assistance is only available to householders who had registered their system prior to February 1st 2013. 

Registration of Septic Tanks/Domestic Wastewater Treatment Systems

All queries relating to septic tank registration should be directed to ‘Protect our Water’. For full details visit: 


Private well water supplies are at particular risk of pollution from septic tanks as they depend on good quality water coming directly from the ground. An information leaflet on how to protect your well can be found HERE.  

Back to top