As Irish Water warned the current ban would be extended "across the country" in the coming days, it signalled those who persistently waste water would not go unpunished.
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The utility said that while it did not want to take people to court, it would "review its options in the case of a persistent breach of the order combined with a refusal to pay the on-thespot fine".
Extra staff are being drafted in to man the utility’s helpline, where members of the public can report people breaching the unprecedented order not to water gardens or wash cars with hoses.
A spokesperson said they expected the vast majority of the public would be "law-abiding" and adhere to the Water The situation is `critical’, says Irish Water chief Jerry Grant But Irish Water warned it would act in cases where there is "excessive and continuous usage".
The company did not give further detail on plans to enforce the ban.
He thanked families and businesses who had been making conservation efforts, but warned that the hot and dry weather could be prolonged.
"We have to be mindful of how we are using water and mindful of others," he said.
Irish Water said conserving water now would safeguard supplies in the autumn.
Water usage in the Greater Dublin Area dropped marginally ahead of the ban.