The Environmental Protection Agency has said 1,800 tonnes of raw sewage is entering the Clare coastline each day and the issue will not be fully resolved until 2025.
Noel Byrne, Senior Inspector with the EPA, said the agency has highlighted wastewater treatment issues at Lahinch and Ennistymon to Uisce Éireann (Irish Water) for several years.
"We are aware from our work on the monitoring and site inspections, there are issues. And we have demanded Uisce Éireann put the right solution in place," he said.
Speaking on RTÉ's Morning Ireland, he said that this is critical for the people of Clare and any tourists who visit these locations.
Mr Byrne said there has been a legacy of underinvestment in wastewater treatment over a number of years.
"That has actually been very obvious," he said.
He said there are five areas in Co Clare currently discharging raw sewage into the coastlines.
"Roughly 1,800 tonnes of raw [sewage is] going out per day," he added.
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He said the EPA has been highlighting these areas and Irish Water has been focusing its investment on these.
"The good news is that three of these areas, Liscannor, Clarecastle and Kilrush, will be resolved this year and the remaining two will be resolved by 2025," he added.
Mr Byrne said Lahinch and Ennistymon plants are not working properly and Irish Water has identified the long-term solution for these which is to construct one big plant that will cater for both.
"We need Irish Water delivering on that," he said.
Locals have spent years campaigning about the issue, including Lexi Keating, who believes her daughter suffered E.coli poisoning a few days after swimming at a local beach in Co Clare in 2018.
Speaking on the same programme, she said her daughter, who was two, suffered acute kidney failure and was urgently transferred to hospital where she received life-saving dialysis and care.
"We have no doubt that she contracted E. coli from swimming in the water that day and her case is certainly not an isolated incident," she said.
Ms Keating said the experience was "incredibly traumatic" for their family and her daughter will require specialist care for the rest of her life.
She said her community has been advocating to stop the flow of raw sewage and agricultural run off, she said, adding that it is simply unacceptable.
