Water restrictions across Dublin will last until at least next Thursday, council chiefs have revealed.
Up to 1.2 million people across Greater Dublin, parts of Kildare and Wicklow, have been being warned supplies are being cut off from 8pm each evening to 7am each morning.
Dublin City Council initially said the problem would be solved by Monday, but tonight said the restrictions will remain in place until at least Thursday.
"We are reviewing the water supply situation on a daily basis and a decision will be taken when appropriate, to change the current level of restrictions," it said.
"We wish to once again urge consumers all over the Dublin region to conserve water, in an effort to assist us in restoring levels in our treated water reservoirs to normal.
"It should be stressed that there is no problem with the quality of treated drinking water or with storage levels of untreated/raw water."
Water supplies in and around Dublin were affected because of problems at one of the state's biggest treatment plants, Ballymore Eustace, Co Kildare.
Production there has been cut by about a fifth because of water supplies entering the system a different colour and turbidity or cloudiness than the system is used to handling.
It is suspected the fine, dry summer followed by periods of heavy rain over the last few weeks has created an unusual balance in the raw water.
Engineers are in talks with various chemists and water treatment experts from overseas who have experience of similar treatment crises in a bid to identify the problem.
The council said production tests are ongoing, but that supplies are still at a level well below that required to meet demand and urged the public to conserve water.
"Coupled with this, storage levels at our treated water reservoirs remain at an unsustainably low level," it added.
Businesses claim they are losing 600,000 euro a day because of the shortages.
Meanwhile, several households complained they have been left with dirty water since taps are turned back on.
The council said householders experiencing discoloured water should run taps clear for two to three minutes.
It also maintained it could take two to three hours from when valves on the pipes were opened in the morning at 7am for full supplies to filter to every home and business in Greater Dublin.