THE unusually hot summer is believed to have caused a rise in the acidity and clouding of Dublin's main water supply.
The night-time suspension of supply, which has hit the restaurant trade badly in the city, is likely to continue until the end of this week and maybe even longer.
Dublin City Council is saying that water staff are uncertain of the cause of the changes in water and have called in chemists from abroad to help analyse and fix the problem.
The rise in acidity and turbidity is, however, believed to be linked to the hot, dry summer. Countries with a hotter climate than Ireland maintain reserves for situations like this but there is almost no spare capacity in the supply of drinking water to Dublin.
The change of the pH levels – the increase in acidity – in water supply is not particularly harmful in itself but can react with pipes, especially those which rust in the case of iron pipes and blue staining in copper pipes. The resulting contaminants can seep into the water, which could pose a health problem.
The turbidity, or the clouding of the water, is caused by increases in suspended matter, including clay, silt and micro organisms.
The water restrictions are affecting more than 1.5 million people, and some restaurants in Dublin city centre had to close on Friday night when they were unable to wash dishes and toilets.
Eamon O'Reilly, chef and proprietor of Dublin's award-winning One Pico in Molesworth Street, had to close his packed restaurant on Friday night after his water ran out at 8.30pm.
Mr O'Reilly, who was in talks with Dublin City Council yesterday, said: "Apparently the water pressure fell, so water couldn't get into the tank. The council is working outside to see if they can do anything to get the pressure back up. We have 130 bookings for tonight and we are hoping the pressure comes back."
While the problems persist, the water supply is running at 50 million litres beneath the Dublin region's daily requirement of 530 million litres.
The council officials say it is only through the implementation of nightly restrictions that it can address the shortfall. They would only comment that it was still not clear what caused the "characteristics" of the water to change.
The problem first arose around 10 days ago, but the council was able to rectify it. However, it re-emerged last weekend, and tests are currently under way to identify the cause. Restrictions will continue until the problem is resolved, they said.
Tourism Minister Leo Varadkar has also expressed concern at the loss of supply. He said: "Obviously, anything that affects business and tourism, I am concerned about. I do think the city council could have done a better job in terms of communication. We know the problem is in Ballymore Eustace, but we don't know exactly what the problem is."
The council has apologised for the restrictions and asked customers to "bear with us".
"An analysis of the current situation carried out at Ballymore Eustace water treatment plant has shown a stabilisation in production at the plant," it said.
Despite this stabilisation, production at the plant is still at a level well below that required to meet demand.
Coupled with this, storage levels at our treated water reservoirs remain at an unsustainably low level. It stressed that there was no problem with the quality of treated drinking water or with storage levels of untreated water.
"A series of tests currently being conducted at Ballymore Eustace involves adjusting the various inputs to the treatment process, with the objective of identifying what caused the slowdown in production and how to resolve the issue," it said.
"Dublin City Council engineers and our central laboratory technicians continue to work 24 hours a day to identify the cause of the problem and to mitigate the effects."
The council conceded that "it may take some time to completely resolve the issue".
Meanwhile, work to install water meters at Littlepace in west Dublin had to be temporarily suspended following a protest by anti-austerity activists.
A spokeswoman for Irish Water said there was a "brief cessation of work for five to 10 minutes due to health and safety concerns that the 25 protesters were too close to the barriers around the area where meters were being installed.