The Environmental Protection Agency says it's not happy that Irish Water haven't yet managed to resolve high levels of a chemical in the North East Regional Supply in Roscommon.
The EPA issued a directive to the body at the end of last year and while Irish Water indicated that they hoped to have the matter dealt with by the middle of this year, that hasn't happened so far.
Levels of Trihalomethanes, or THM'S were found to exceed recommended levels in the supply in north east Roscommon and in central Longford.
The EPA says there is concern about people drinking water with higher than recommended levels of THM's.
Cormac McGearailt who's an Inspector in the Office of Environmental Enforcement with the EPA says they will consider more action if the supply in Roscommon isn't improved soon.
"Those works haven't been finished yet. We have been keeping in close touch with Irish Water to ensure that works are moving forward, but they haven't been completed and that's not something we're happy with. In those kind of cases, where directions have been issued and dates aren't being complied with, that's something we have to take very seriously and consider we need to take further action to ensure that works are complete. Sometimes a lot of work needs to be done in the network, but those standards need to be complied with".