Irish Water has promised to eliminate most boil notices by the end of 2015 and the remainder by the end of the following year.
The utility company said the elimination of boil notices was its first priority.
Some boil notices have been in place for eight years.
Speaking on RTÉ's Morning Ireland, Irish Water's Head of Communications Elizabeth Arnett said up to 20,000 people were still affected by boil notices.
The promise came as Irish Water published its three-year capital investment plan.
It said it would invest €1.8bn in water and waste treatment improvements over that period.
Irish Water said the plan would deliver improvements in drinking water quality, leakage, water availability and waste water compliance.
More than 700 million litres of water is being lost per day through leaking pipes.
Irish Water said the leakage programme, combined with the completion of existing works at Ballymore Eustace and Leixlip, will solve Dublin's water issue in the short-term.
However, it said the project to divert water from the River Shannon to the Greater Dublin Area will still be required in the medium-term.