Crèches, nursing homes and hotels using their own wells for drinking water could pose a serious health risk.
That is a finding of The Environmental Protection Agency whose latest report expresses concern about the standard of some private water supplies.
One million people in Ireland get their drinking water from private water supplies.
However, this EPA report says many of these supplies are not registered with local authorities and do not get tested properly to ensure the water is safe.
Last year E. coli - the contamination linked to human or animals waste - was found in 51 small private water supplies serving commercial buildings like hotels and B&Bs or public buildings like schools and crèches.
Meanwhile, no E. coli testing was reported for more than 700 other small supplies.
The EPA is concerned about the health risks, particularly for children and the elderly, and it is urging owners of all private water supplies to register with their local authority.
