Regional supply and demand graph
Million litres per day.
Available supply is the amount of water we can take from our three sources:
- Hutt River
- Combined flow of the Wainuiomata and Orongorongo rivers
- Waiwhetu Aquifer - a natural underground reservoir beneath the Hutt Valley that is fed by river-water seeping down into the ground.
In the summer months supply typically goes down, as there is less rain. There is also a cap on the amount of water we can take from our rivers, due to environmental reasons.
We have two large storage lakes at Te Marua as back-up to the river supply. The lakes are filled from the river when it is clean and there is plenty of water available.
During a typical Wellington summer we normally tap into our lake supply in February/March.
Demand relates to the amount of water the region in using. It usually increases in summer due to residential outdoor water use increasing.
To comfortably supply demand in the region, we have a target of 160MLD.
Every year to help us manage summer demand garden watering restrictions in Wellington, Lower Hutt and Porirua are in place during daylight saving (and all year round for Upper Hutt). However, when there are long periods of dry weather around the region these restrictions can be increased.
There is currently a ban on sprinklers, irrigation systems and unattended water use in the region.