Irish Water has completed works on the Swanlinbar water treatment plant in Cavan.
The €500,000 upgrade works have seen the water scheme removed from EPA's remedial action list.
It was added to the list in 2019 after a failure of its disinfectant system lead to a Do Not Consume notice being issued.
The works include the installation of pH correction units, a raw water shut-down system, improved alarms and shut-down systems and an upgrade of the disinfection process.
Irish Water says over 300 customers in the Swanlinbar area will benefit from the works.