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Household water use in Auckland

 
From February to September 2008, the Building Research Association of New Zealand (BRANZ) monitored the water use of 51 randomly selected households across the Auckland region.

 

Water use identified in the 2008 BRANZ study

 
Season
Average residential water use
Median residential water use
Summer
179 L/p/d
143 L/p/d
Winter
174 L/p/d
130 L/p/d
 
Overall, the highest indoor water end use was the shower, followed by the washing machine and the toilet. The figure below shows how water use changes between summer and winter.
 



Auckland residential water end use (2008. BRANZ study)

 
The highest water uses are reviewed in more detail in the 2013 Auckland regional Demand Management Plan. Outcomes of the study are highlighted below.
 
Showers
On average showers are used less than once a day per person, with an average length of 6.6 minutes in the summer, 7 minutes in the winter and with an average flow rate of 8 L/min. A wide range of flow rates were recorded, ranging from 3 L/min, up to a maximum of 20 L/min. It is very likely that the average of Auckland showers has a flow rate closer to 13 L/min as recorded in many New Zealand and Australian cities.
 
 
Toilets
Most of the toilets analysed had a poor water use, with only 6% of toilets being classed as two stars or better on the WELS water efficiency rating. Toilets use an average of 6.7 L/flush, and are flushed just less than five times per person per day. Replacing inefficient toilets could have a significant impact on water demand.
 
 
Washing machines
The BRANZ study found that the average water use for a load was 122 L/load, with a maximum of 190 L/load. On average there were 5.6 loads per household per week, or 0.35 loads per person per day. Replacing washing machines with more efficient models (or front loading washing machines which use only around 60L/load) would greatly reduce residential water and wastewater volumes.
 
 
Leaks
Leaks include dripping taps and other fittings, as well as leakage from the supply pipe between the meter and the house. Leakage has a large impact on water use if undetected or ignored, and when fixed has the potential to provide significant savings.
 
 
Outdoor use
Outdoor use is dependent upon the season, with higher water use in summer. Only a small number of households were responsible for the high usage and were those households with both a swimming pool and a spa pool. The single highest outdoor usage was irrigation, which highly contributes to peak demand at times when water resources are scarcer.