Rain is battering the region and pelting down in Northland as Civil Defence warns of severe thunderstorms this afternoon.
The Coromandel and the Bay of Plenty are being warned to expect up to a month's worth of rain today - on top of the month's worth that has already fallen across the saturated regions this week.
About half of Auckland's water comes from four dams in the Hunua Ranges, where flash flooding took place after heavy rain yesterday. Because of unsettled silt in the dams, the Ardmore Treatment Plant was treating about half of what it normally did.
As a result, Aucklanders are being asked to reduce their water use by 20 litres a day until the end of the month.
The last time Auckland faced such a crisis was during the 1994 drought, a Watercare spokeswoman said.
Reductions in water consumption over the past 24 hours have resulted in some savings, but more is required.
Watercare have maximised the production from the region's other four large water treatment plants, including Huia and Waikato.
The spokeswoman said a long period of dry weather is needed for the water in the dams to settle so the Ardmore Water Treatment Plant can resume full activity.
Ways to save water
• Cut your shower time by two minutes. Approx saving = 16L
• Turn off the tap when brushing your teeth. Approx saving = 4L
• Only run your dishwasher when full
• Only run washing machine when full
