Household Utilities: Potable Water: Water Requirements.
Water efficiency must be part of the planning of a sustainable house.
An international analysis of water usage patterns showed that middle
income consumers use 180 litres of water per capita per day (Lcd), lowest
income consumers use 50 - 55 Lcd, and the minimum supply for drinking,
cooking and ablutions is 25Lcd (Vale, 1996).
Residential water consumption in Sydney 1995 is broken down as follows:
|
Water Usage
|
Percentage
|
|
Toilet
|
23%
|
|
Shower
|
20%
|
|
Bath
|
3%
|
|
Clothes washing
|
16%
|
|
Kitchen
|
10%
|
|
Garden
|
25%
|
|
Basin
|
3%
|
An
average household, the annual wastewater pattern for the toilet, bathroom,
laundry and kitchen can be assumed to be consistent from one year to
the next. Large, seasonal increases can occur from activities such as
watering the garden and filling the swimming pool.
The following table shows the weekly water usage by the Newtons, whilst
living in a typical house for 2 adults. A water saver shower rose and
dual flush toilet system are used. Note that the weeks of 20th and 28th
of February show the impact of watering the garden, more than doubling
the household water consumption.
Historical water usages prior moving to
the Newton House
|
Date
|
Water meter reading
|
|
|
13.02.00
|
44 354.85
|
-
|
|
20.02.00
|
48 797.10
|
|
|
28.02.00
|
54 058.55
|
|
|
05.03.00
|
55 937.90
|
|
|
12.03.00
|
57 497.50
|
|
|
19.03.00
|
59 026.80
|
|
|
26.03.00
|
60 654.05
|
|
|
02.04.00
|
62 315.90
|
|
|
09.04.00
|
64 383.28
|
|
|
16.04.00
|
65 825.15
|
|
|
23.04.00
|
67 207.32
|
|
|
30.04.00
|
69 086.58
|
|
This
data shows the Newtons average consumption of water to be 121.30 litres
per person per day, excluding the water used on the garden. The Newton
House will use greywater to irrigate the garden.
Water consumption can be decreased by:
1. Waterless toilets, dual flush toilets,
or the use of recycled or storm water in the cistern.
2. Treated greywater used for lawn and garden watering.
3. Water aerators on showers and taps to reduce flow whilst maintaining
pressure.
4. Flow control valves that adjust the pressure differences between
the hot and cold supplies, preventing sudden drops in pressure, and
wastage involved in manually adjusting water pressure and temperature.
5. Insulating hot water pipes which reduce heat loss and therefore
the water loss incurred waiting for hot water.
6. Lowering the hot water thermostat, as most hot water is too hot
for domestic purposes forcing the consumer to add cold water to it.
7. Locating the hot water system as close as practical to the bathroom.
This reduces the length of piping the water has to travel and the amount
of cold water wasted waiting for hot water.
8. Selecting domestic appliances with low water consumption. For example,
a Hoover 545 washing machine uses 115L for a full 4 kg load of washing
and an AEG Lavamat 645 uses 68 L for a 5 kg load (Vale, 1996).
9. Composting food waste rather then using garbage disposals.
In Australia there is a voluntary National Water Conservation Rating
and Labelling Scheme for showers heads, taps, washing machines, dishwashers,
urinals and toilets. The ratings used are- 'AAA' excellent, 'AA' high,
and 'A' acceptable. An 'AAA' rated shower rose will still use 9 to 11
litres of water per minute.
Links
http://www.nature-loo.com.au
http://www.housing.qld.gov.au/builders/research_house/pdf/water_use_report.pdf
