Irish Water is appealing to householders to ease up on non-essential use of water as it revealed we are using 24 litres more each every day while at home under lockdown.
It warns that the combination of the prolonged dry spell, additional daily use and an expected surge in demand when businesses reopen will put already strained supplies under even greater pressure.
Domestic use in total is up 20pc, which amounts to demand for around 120 million extra litres of water a day.
Closing businesses and schools reduced usage in the non-domestic sector. But it may not be enough to compensate for thirsty households that, even under normal circumstances, make up two-thirds of daily demand.
Irish Water said restrictions were not currently under consideration, but cautioned: "Our water supply is still under pressure."
It added: "Water treatment plants are already working to their maximum capacity."
The immediate concern is the impact on supply when lockdown restrictions begin to be lifted early next week.
"When Government restrictions are lifted, many commercial premises will need to use extra water to clean and flush their plumbing systems and storage tanks or to complete deep cleans, while water usage in homes will continue to remain higher than normal," it said.
The concerns were echoed by the National Water Forum. "We are already seeing lower river and groundwater levels," Dr Alec Rolston said.
"If dry conditions persist over the coming months, how water conservation measures may be enacted during a time of a global pandemic, where water and hygiene is crucial to combating the spread of Covid-19, remains to be seen."
Irish Water managing director Niall Gleeson said the utility was on drought alert.
"We are also conscious that we have had an extremely dry spell so we are continually monitoring our water sources for any signs of drought," he said.
He stressed it was important that nobody skimped on handwashing. "However, there are some ways to conserve water that will not impact on hygiene," he said.
Householders are being asked to use watering cans rather than hoses in the garden, to use a bucket and sponge to handwash cars in preference to using powerwashers and to take showers instead of baths.
Irish Water is also asking that any dripping taps be fixed where possible - and it says it will continue its own emergency leak repair work, and other repairs as far as possible, taking into account Covid-19 restrictions.
"It is essential that we act now to protect our supply and safeguard our water for essential usage," Mr Gleeson said.
Irish Water has powers to implement a water conservation order on particular areas or the country as a whole if water levels get too low.
In the drought of summer 2018, a hosepipe ban was introduced in the Greater Dublin Area at the beginning of July and extended to the rest of the country weeks later.
Water pressure was also reduced at night time, leading to loss of supply in some areas.
Extra domestic demand is a feature in the UK too under the current lockdown.
Irish Water said checks with utilities in Britain showed they were reporting on average additional daily usage of 27 litres per domestic customer.