Dublin has just seventy days' worth of water left. Supply across the city and county is still critical following the heatwave and dry weather.
Irish Water has warned that supplies could fail in the Greater Dublin Area in just over two months' time unless action is taken.
Despite a nationwide hosepipe ban remaining in place, and overnight restrictions across most of Dublin, levels are extremely low.
If supplies were to fail, 1.5 million people would be affected.
Jerry Grant, Head of Irish Water, said "the risk of failure of the Dublin water supply is high, and it's high because we are drawing it all from one source".
"We are using a lot of it in leakage in the network and in households and in business and we need to use less", he warned.