Water levels in the Shannon are expected to peak this weekend, and fears of further flooding are now arising after heavy rains are forecast for Saturday.
Army units were deployed in areas of Clare and Limerick to assist with flood defences and evacuation duties if the need arises.
It is understood that brackish water and sewage came up through drains in Athlone, after the river burst its banks.
The Irish Red Cross is currently distributing bottled water to residents affected by flooding.