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Reducing water demand by domestic consumers

Read about the concept of reducing water demand by domestic consumers as one way of strengthening water security.
© Cardiff University

In this activity, we introduce the concept of reducing water demand by domestic consumers as one way of strengthening water security.

We’ll do this through the example of Cape Town, South Africa, and some examples from other places around the world. The aim is that you gain an understanding of how water behaviour can have a strong impact on water security.

After completing this activity you should think more critically about:

  • the role of behaviour in the amount of water we use directly
  • measures to reduce our demand for water
  • how you might reduce your own water footprint

How much water do we use?

The amount of water we use for domestic purposes is closely related to its availability, the amount of effort it takes to access it and the level income we have.

Where water is plentiful and comes out of a tap in our house then we tend to use more of it, with those on higher incomes tending to use the most. Those living in hot and arid climates also tend to have a higher demand for water, all other things being equal.

In Table 1 we can see some figures for the average amount of water used per person per day in different countries. Making comparisons is difficult and we should try to distinguish between the amount of water used by consumers from that supplied.

A surprising amount of water supplied (figures of one third are not unusual) is lost through leakage before it even reaches the consumer.

This table shows the average daily domestic water use per person for selected countries

Country Average daily domestic water use (litres per person)
UK 149
South Africa 115
USA 333
Germany 121
Australia 340

Averages are always problematic, as they hide inequalities and differences in use. These might be geographic, such as in Australia where it’s reported that average daily water use ranges from just 100 litres per person in some coastal areas to more than 800 litres per person in drier inland areas.

The most significant reason for differences in average water use though tends to be income related. Those with lower levels of income tend to use less water.

This graph illustrates this with an example from Windhoek, Namibia, demonstrating the divergence from the average based on a survey undertaken in 2010.

This graph shows the divergence from average consumption by community: High income community (~95%), Middle income community (~60%), Low income community(~17%), Informal settlement (~-75%) Variations in average amount of water used by households (%)

The reasons for such differences are related to lifestyle as well as the availability and cost of water. Watering a garden or washing a car takes a lot of water, and in the house itself things like using a washing machine will also add to the total amount of water used.

For most households, simple actions like flushing a toilet or taking baths and showers can rapidly add to the amount of water being used.

This table shows some estimates by one Australian water council of the typical amounts of water required by simple household activities.

Action Water consuption
Toilet flush (single flush cistern) 12 litres
Bath 100 litres
Shower (10 minutes) 200 litres
Dishwasher load 50 litres
Brushing teeth (with tap running) 5 litres
Drinking, cooking, cleaning per person per day 10 litres
Hand basin (per use) 5 litres
Garden sprinkler (per hour) 1000 litres
Garden dripper (per hour) 4 litres
Car washing with hose 200 litres
Hosing driveway 100 litres
Total daily consumption per household 900 litres

Many of these activities will be spread over a number of days, or across a family. However, the table indicates how much water consumption can be affected by just a few common actions.

Water saving technologies, such as low flow shower heads can help reduce consumption, but sometimes more radical actions are needed, especially during periods of acute water shortage.

In the next step, we’ll illustrate this with a recent example from Cape Town, South Africa.

Over to you

  • Based on the estimates provided above, how much water do you think you personally use daily within your household?

Let us know in the comments.

© Cardiff University
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The Challenge of Global Water Security

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