Water shortage looms for region's cities

Low river levels will see Greater Wellington’s Wainuiomata Water Treatment Plant shut down in about a week's time unless the Wainuiomata catchment area gets good rainfall. The Wainuiomata plant is one of three water treatment plants that supply water to the region’s four cities (Lower Hutt, Upper Hutt, Wellington and Porirua).

“We’re increasingly concerned about getting through this summer without a water shortage,” says Cr. Rex Kirton, Chair of Greater Wellington’s Parks, Forests and Utilities Committee. “Unless water use eases, the closure of the Wainuiomata plant will force us to ask the cities to ban the use of sprinklers and irrigation systems. We’re working with the cities now to prepare for that.”

The potential loss of supply from the Wainuiomata plant comes with the region's other water sources being under increasing pressure from low inflows, high demand for water and continuing expectations of a long summer, stretching until the end of March or further.

Greater Wellington supplied an average of 184 million litres daily last week to the region’s four cities, with supply peaking at 196 million litres on 29 January, the highest daily total in two years. With just a few millimetres of rain falling in Wellington since 8 January, there is a real threat of demand rising further, as annual water use typically peaks during February.

"We’re asking everyone to make an extra effort to go easy on water use in the coming weeks, especially gardeners,” says Cr Kirton. “Ideally, we’d like to see watering by hand. If people are using sprinkler or irrigation systems, they should be timed to 30 minutes per session. Gardeners should also target water to the roots of plants at a rate that the soil can absorb.”

Cr Kirton urges people to follow their local council’s water restrictions, which can be found on local council websites. For more tips on how to conserve water go to www.bethedifference.co.nz

See below for background information on water supply.

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Background information

Greater Wellington supplies water to the region's four cities from three main treatment plants: Te Marua, Wainuiomata and Waterloo. If the Wainuiomata plant was forced to close, Te Marua and Waterloo would have to cover the shortfall.

At present, available water for treatment at Te Marua, from the Hutt River, is down to about 50 million litres daily – nearly twice that volume is needed from Te Marua to keep pace with demand. The balance is coming from Te Marua’s storage lakes, which currently hold about 50 days' supply at the cities’ current rate of use. However, the amount of water taken daily from the lakes will need to increase if dry conditions persist, and the lakes could possibly run dry by March.

The Waterloo plant’s aquifer source is near the trigger level where Greater Wellington would have to reduce its water take.

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