Irish Water says the repair of a major leak in Ballinamore will save more than 330,000 litres of water per day.
A statement issued by the authority says there was a challenge in locating the water loss due to the limited information on the underground public network.
Following intensive investigations works a substantial public water mains leak was detected in Ardrum.
None of the leaked water was surfacing but Irish Water says that invaluable local knowledge helped solve the issue.
The company says the amount of clean water saved is enough to supply almost 2,500 people, or the population equivalent of Manorhamilton and Kinlough for the day.