Sewage plants serving rural areas 'primitive'
Irish Water has identified "major problems" with smaller sewage treatment plants serving rural communities across the country.
The utility said that current facilities in some parts are "primitive", and causing "chronic local pollution".
And it warned that it has yet to accurately assess how much wastewater is being treated and discharged into waters.
There is also an issue about the lack of a licensing regime for businesses which discharge wastewater to sewers, which is leading to odour complaints and blockages.
The company said it believes there are 1,155 wastewater treatment plants across the country, but admitted it did not have a "good picture" on the amount of sewage they treat, or are designed to accommodate.
Around half of the total serve small populations of less than 500 people, and investment in the past tended to be focused in large urban areas.
The situation is complicated by rigorous EU rules on the quality of effluent being discharged into waters.
"Our problem, and the piece we need to work on, is what can the environment take," a source said. "There is a lack of knowledge about the number of (trade) customers, and the sewer network."
The company is undertaking a review of licensing for trade discharges, saying that some businesses have no effective controls in place to reduce the amount of fats, oils and greases (FOGs) entering the network.
This not only leads to problems with odour and blockages, but can also impact on the treatment process.
The roll-out of a national licensing regime, as currently applies in Dublin, is being planned, and will take into account business costs, local factors and the scale of the business concerned, it said.
It also plans to upgrade at-risk plants or those under- performing. This could include installing additional tanks.
The utility is now measuring the size of the plants, and trying to rectify the pollution issues.
One solution is using modular plants, where capacity can be increased in stages to accommodate higher loads.
At Athea in Limerick, wastewater was historically discharged into the River Galey with minimal treatment.
The plant was to be upgraded to cater for long-term population growth of 1,500, but the utility has reduced its capacity for 600 which is sufficient for current needs, while allowing for an expansion in population.
This approach will be used for smaller urban areas as it provides improved treatment at a lower cost, and can be expanded to allow for future growth.