Residents in Fingal in Dublin will find out later whether it is now safe to swim at their local beach.
Twelve beaches in the area have had 'no swim' notices in place since Tuesday, after a pump station overflowed following heavy rain.
Rainwater that would normally flow through the sewers and into the waste water treatment works, instead flowed out to sea.
Fingal County Council will get the water test results back today to determine whether the water quality is now safe.