A hosepipe ban for the greater Dublin area comes into effect from Monday
Irish Water is continuing to call for members of the public to 'conserve water as much as possible' - saying conservation efforts will be necessary for months.
It comes amid high demand for water across the country, with the utility saying further restrictions will become unavoidable if demand doesn't drop to normal levels.
39 water supplies are already under night-time water restrictions, while more than 100 water supplies are at risk due to high consumption.
A drought warning has been issued by Met Éireann for the entire country until Friday, with "little or no rain forecast for most areas over the coming week".
According to Irish Water, the need for conservation will continue well beyond the current hot weather.
Irish Water's Kate Gannon said: "We urge customers to conserve water and to work with us by following our tips such as taking short showers instead of baths, turning taps off when brushing teeth and not using hosepipes in gardens and limiting use of water in paddling pools.
"It will take months for water levels to restore in raw water sources such as rivers, lakes and ground water supplies and for levels in our treated drinking water reservoirs to restore. We are asking the public to continue to conserve water in the months ahead and to follow our advice for longer term water conservation.’’
Meanwhile, the previously announced hosepipe ban for the greater Dublin area will come into effect tomorrow.
It will be in force for at least a month, with those in breach facing a €125 fine or possible prosecution.
Use of hoses will be banned for purposes such as filling domestic pools or watering gardens.
Speaking ahead of the ban coming into force, Irish Water General Manager Eamon Gallen explained: "We expect that most people will be law-abiding, and that the order itself will be adhered to by the vast majority of the public.
"We will act in cases where there is excessive and continued usage, but we'd hope this would only be in a small number of cases."
Mr Gallen added: "During this time we'll monitor usage on a daily basis, and if required we'll complete special reads of meters to understand high usage in certain areas of the network.
"We're not sitting down, watching everybody's consumption on a daily basis. We will spot high consumption alright, but it's not that we're chasing down people using the meters - we're using the meter data primarily to find where there are leaks."