Too much water makes you WEEP

This Issue This is a part of the Water heating and use feature

By - , Build 99

Showers use more water than any other domestic activity, according to a BRANZ research project looking at where our water goes.

Water end-use for the 2006 winter monitoring period.

Water is already an issue in many parts of the world, with major global shortages within the next century being predicted. In New Zealand a large proportion of drinkable water is flushed down the toilet, used for intensive irrigation, or wasted through water-inefficient appliances and behaviour.

In 2005, BRANZ began looking at ways in which water end-uses, such as showering, flushing the toilet and using the dishwasher, could be monitored in residential homes. In July 2006, 12 homes on the Kapiti Coast were fitted with special equipment attached to a high-resolution water meter for monitoring as part of the Water End-use and Efficiency Programme (WEEP). The aim is to determine where water is being used, for how long, at what times and at what flow rates.

Following are the results for the winter monitoring period, which finished at the beginning of October 2006. Data is still being collected for the summer monitoring period.

Showers the biggest user

The biggest end-use was the shower, which accounted for 27% of total water use. Other high users were the washing machine (24%), the toilet (19%) and taps (14%).

The average shower was 7.7 minutes long, and used an average of 82 litres of water. A top-loading washing machine used an average of 135 litres per load, compared with 51 litres for the more water-efficient front-loading machine. On average 0.8 loads were washed per home per day. This equates to about 39,000 litres of fresh water per house annually when a top-loading machine is used, compared with 14,000 litres for a front-loading machine. In New Zealand 96% of washing machines are top-loading.

Water end-use for the 2006 winter monitoring period.

On average, a total of 168 litres of mains water were used per person per day during the winter period. Summer values are expected to be higher.

Ways to save water

Water efficiency means using less water for day-to-day activities. This can be achieved by smart appliance choices, and by installing water-saving fixtures and fittings. Both can be achieved at a relatively low cost.

One effective water-saving fixture is a low-flow shower head. The study found that 65% of the showers monitored had a flow rate exceeding 9 litres per minute. By comparison, water-efficient shower heads can use less than 7 litres per minute while still providing adequate shower comfort. They also save on energy used for heating water. Dual flush toilets, waterless toilets or tap aerators are other options for saving water.

However the first step towards water efficiency is to fix all leaks and dripping taps. Leaks accounted for 4% of the total water used in the case study homes. During the first month of monitoring, data analysis showed one home had substantial leaks, accounting for 56% of their total water use.

Water conservation can be improved significantly by installing a rainwater or grey water system. Homes with these systems use much less mains water than homes without. Not all end-uses require mains water of drinking quality. The water used for the toilet, laundry or outside irrigation can easily be supplemented by rainwater, even in urban areas. These systems can be put in place when building a new home, or installed during retrofitting of existing houses. The use of grey water is still controversial in some areas, so check with your council on what the regulations are.

The majority of outside water use is for gardening and can be significantly reduced by smart garden design and management techniques. Choosing plants which are suitable for the climate you live in is one example.

Looking to the future

Water is still seen as an unlimited resource by many, and tends to be undervalued. Many local bodies, such as the Kapiti Coast District Council and the Christchurch City Council, already have water restrictions in place during part of the year.

Water conservation is an important first step towards reducing our environmental footprint. To start saving water, replace a top-loading washing machine with a water-efficient front loader or install a low-flow shower head. It is also possible to use rainwater or grey water to supplement mains water supply. This can also save money in areas where water is metered.

For more

The full WEEP report will be available at www.branz.co.nz. This work was funded by Building Research.

Download the PDF

More articles about these topics

Articles are correct at the time of publication but may have since become outdated.

Water end-use for the 2006 winter monitoring period.

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