We supply about 140 million litres (ML) of water per day (on average) for Upper Hutt, Lower Hutt, Porirua and Wellington.
Our supply serves a resident population of almost 400,000, so on average we provide about 350 litres per resident each day, or 3-4 bathtubs each. Not all of this water is used in homes. City council estimates show that households use a bit over 60% of our total supply. Other users include industry, businesses, schools, hospitals, the fire service and councils.
The graph below shows the changing levels of water use at different times of the year and contrasts average daily supply with the highest daily supply for each month. Increased water use outdoors, especially on gardens, is behind the higher peaks in spring and summer months.
Water use averages a little over 140 million litres daily. During periods of dry weather in summer, daily demand has peaked at almost 200 million litres, or 45% more than the average daily demand during winter.
Total demand for water from the four cities has decreased in recent years, from about 56,000 ML a year (2007/08) to about 50,000 ML (2012/13), or a bit less than 1,000 ML per week on average. If Wellington's Westpac Stadium were a reservoir, this weekly volume would fill it.
This lower demand is likely due to a number of factors including reduced leakage, improving efficiency of appliances and fittings (washing machines, toilets, taps and showerheads), publicity, changing housing and development types, and water-saving behaviour.
Climate also plays a part in the demand and provides a level of complexity when assessing influences, with the variation in the region’s seasonal demands explained in part by climate.
For more information about water supply volumes see our latest Water Supply Annual Report which is located in our Plans & Publications section (see under Our Services).