Water restrictions are likely to remain in place for the foreseeable future, with 70 days' supply left in the main reservoir serving the greater Dublin area, Irish Water has said.
Levels at the Poulaphouca Reservoir in Co Wicklow have fallen from 150 days' storage in early May down to 70 days at present, according to the utility's Managing Director Jerry Grant.
Speaking on RTÉ's Morning Ireland, Mr Grant said that in the south, midlands and east of the country "we are managing with very depleted supplies".
He said the extreme weather this year, with snow in March and a drought in summer, "has underlined the lack of resilience in our water system".
Mr Grant also said that much of the water network in the capital was not fit for purpose and was leaking.
Of the 9,000km of pipes in Dublin, he said 25% existed pre-1960 and were "cast iron and pretty corroded".
Half of the network was built between 1960 and 2000, with much of the construction developer-led with very little development control.
"The reality is the frequency of bursts on the pipes laid in the 1980s and 90s is every bit as bad as the pipes laid in the 1930s," he said.
Mr Grant added that 70km of the 9,000km pipe network have been earmarked for improvement works.
With plans to augment the water supplies to Dublin via a pipeline from the River Shannon unlikely to be completed for a number of years, Mr Grant said such works will be taking place year in, year out until then.
He said the hosepipe ban, which was due to be lifted at the end of this month, may continue to be enforced in the east and south of the country until October.
Despite recent rainfalls, the soil moisture deficit in some of these areas is still up to 75mm.
He added that current night-time water restrictions in the greater Dublin area were likely to be maintained until winter rains restore supplies in the region's reservoirs.