Septic tanks inspections needed to prevent polluted drinking water, EPA warns

THE 350,000 septic tanks servicing rural houses countrywide must be inspected more to ensure they are not polluting drinking water and do not pose a hazard to protect public health, the Environmental Protection Agency (EPA) warned yesterday

Local authorities are responsible for granting planning permission for septic tanks for one-off rural houses and enforcing the law.

But the latest EPA groundwater report has revealed that many rural group water schemes are contaminated and the main sources of this pollution are septic tanks and small wastewater schemes, EPA programme manager Gerard O’Leary said.

“Local authorities must ensure that septic tanks comply with their planning permission - this includes a regular programme of testing and monitoring - at least once a year,” Mr O’Leary added.

This is because domestic wastewater contains many substances that are undesirable and potentially harmful to human health and the environment, he said.

The main reasons why septic tanks and small scale domestic wastewater treatments pollute groundwater are poor design, siting and installation, he said.

But now independent research on the performance of septic tanks and the new mechanical systems commissioned by the EPA has found that both are equally effective if they have the proper percolation area, are built on the right site and are properly installed.

Researchers from Trinity College’s Environmental Engineering Group carried out four separate field trials on the two systems that were purposely built for the experiment over a 12 month period.

“There is a lot of myth about septic tanks and percolation area and we wanted to have an independent assessment of the guidelines the EPA produced for the installation of these in 2000,” Mr O’Leary said.

These independent tests proved that the EPA guidelines for the selection, design and operation of these two wastewater treatments were correct. The guidelines can be found on the EPA website: www.epa.ie.

However, wastewater treatment systems for single houses are exempt from the very stringent EU Ground Water Directive under which the European Commission is currently prosecuting Ireland.

The Commission is claiming there are widespread breaches of the directive here and that a County Wicklow landfill site at Ballymurtagh licensed by the EPA is one example of these breaches.

This Commission claims that “dangerous substances” at the landfill were allowed to pollute groundwater and the waste licence granted by the EPA in 2001 infringes article 4,5,7, 10 of the directive.