‘Unprecedented’ rain puts Auckland water at risk

WATERCARE is defending its infrastructure after an ‘‘unprecedented’’ deluge of rain forced it to call for widespread water restrictions across Auckland, as the city grapples with its biggest water shortage in 23 years.

The councilcontrolled organisation warned yesterday that if the city’s residents did not cut their daily water use by 20 litres each — the equivalent of two buckets — it would introduce partially treated water to the supply, resulting in notices that water should be boiled. Fifty million litres a day must be saved.

People are being encouraged to ban baths, take short showers and neither water their gardens nor wash their cars.

Watercare spokesman Mark Bourne said that in his 27year career he had never seen weather like this. About 240mm of rain fell over 24 hours in the Hunua Ranges on Tuesday night, putting the agency’s water treatment plants under strain.

The rain caused unsettled silt in dams at a treatment plant from which Auckland gets about half its water, meaning it was able to treat only half what it normally did.

‘‘This is unprecedented rainfall. Niwa says the extreme weather experienced this week is ‘off the chart’ and has well exceeded what would be considered a onein100year event,’’ Mr Bourne said.

‘‘While Ardmore is working at reduced capacity, our other treatment plants provide us with resilience to such events.’’

Mr Bourne said that if the savings were not achieved, partially treated water might have to be introduced into the system and a notice to boil water issued.

He held up a glass of untreated water at the press conference that could have been mistaken for orange juice because of its colour.

Aucklanders use on average about 160 litres of water a person a day, about 450 million litres overall.

After a notice was put out yesterday to reduce use, 420 million litres was used but the target was 400 million litres.

About half of Auckland’s water comes from four dams in the Hunua Ranges.