Overnight water restrictions will come into force in many areas of Dublin tonight.
Bray in County Wicklow will also be impacted by the measures which come into effect at 10pm.
The measures are expected to last at least one week.
The first significant rainfall in 40 days over the weekend was never going to be enough to force a rethink on the restrictions to water supplies.
Pressure will be reduced between 10pm and 5am in most areas of Dublin and in Bray in County Wicklow.
That is in addition to restrictions already in place in some schemes around the country.
It is hoped the move will help avoid widespread outages in the autumn.
They are described as 'level 2' - meaning there will be no loss of supply, but people in some high ground or remote areas may see tap water reduced to a trickle.
Irish Water say the decision to lock down the restrictions to these areas was not taken lightly.
Any customers adversely affected by the measure can call the Irish Water Customer Care line 1850 278 278.
- Digital Desk