Water And Sustainable Design
Water is fast becoming a scarce resource. Climate change, water
pollution and increasing urban and rural demand for quality water
is draining natural fresh water resources. As part of eco-friendly
building and sustainable energy programs, water conservation and
management measures are being integrated into home design and adopted
throughout the construction process.
The aim of sustainable water management is to reduce, reuse and
recycle domestic water use, thereby contributing savings in energy
and water. In turn, this reduces the environmental impact of both
transporting water and water disposal over long distances. Such
strategies positively impact carbon emissions, with the hope of
curtailing the climate change, and the treat of impending water
Sustainable water management strategies include:
- Water Conservation
- Water Tanks
- Water-efficient Appliances
Water conservation in homes requires effective plumbing design.
- A gravity hot-water system - lower water pressure results in
less water usage than a mains pressure hot-water system.
- Point of use water heaters - avoids wasting cold water while
waiting for hot water to reach the taps.
- Well-lagged and positioned pipes - helps to keep water hot.
- Water-efficient appliances and fittings
Water Tanks Systems
Water tank systems are used to collect and filter grey water from
sinks and laundries, for use in toilets and irrigation. This is
known as greywater recycling.
Water can be collected from roofs can be recycled for flushing
toilets, filling washing machines and watering gardens.
Greywater from baths, sinks and showers and can be recycled and
reused for watering the garden or flushing toilets. This can save
up to 50% of domestic water use. Used on the garden, greywater requires
no treatment. However, greywater used for domestic purposes requires
some form filtering and disinfectant to remove bacteria and other
Greywater systems require the household use only biodegradable,
non-toxic household cleaning and toiletry products. Fats and additives
are not suitable for even garden usage. Soils should be test regularly
to ensure toxicity or ph issues do not arise.
Urban stormwater systems capture rainwater from streets, carparks
and roofs and channel it into waterways and estuaries. Along with
it pollutants and rubbish enter our natural water sources.
Urban infill has increased the relative area of impervious hard
surfaces leading to erosion, flooding and damage to ecosystems.
Both these problems can be reduced with improved design of drainage
and stormwater systems which use filters and detention systems.
Detention systems harvest rainwater for local recycle, whilst reducing
stormwater run off.
Water Efficient Fittings
Use of water efficient plumbing fittings can reduce the use of
water in the home by as much 30%. This includes:
- Low water shower fittings
- Sensor controlled taps
- Dual flush toilet cisterns - providing low flush and standard
- Displacement devices in toilet cisterns
- Waterless urinals, pressure assisted toilets and dry composting
Most plumbing fittings today must compy with water efficiency ratings.
Labelling for products defines this rating against the national
Hot water pipe work should always be lagged with insulated, ecofriendly
lagging to reduce the water flow before hot water reaches the taps.
Taps and Fittings - account for around 8% of domestic
water use. Tap design impacts water usage:
- Conventional twist taps - use around 4 litres per hand wash
- Water efficient fixtures - use only 2 litres or less.
- Push taps and sensor taps [self-closing]
- Spray taps - reduce flow volume
- Flow regulators and restrictors - restrict flow, regulate pressure
and reduce the force to turn the flow off.
Showers - account for around 20% of domestic water
use. Showers should be more water-efficient than baths, however
the popularity of modern power showers significantly increases the
water usage in a shower. The choice of showerhead can halve water
- Regular showerheads - use around 20 litres per minute
- Low-flow showerheads - use less than 10 litres per minute by
creating finer drops or using pressure powered aeration.
Water Efficient Appliances
Dishwashers - high efficiency dishwashers save both water and energy.
Water efficient dishwashers use only 16 litres of water per load
compared to 40 litres for hand washing dishes.
Washing Machines - account for about 14% of domestic water use.
Modern high efficiency models use less than 50 litres per load,
compared to over 100 litres by older models. NOTE: A full load is
always more water efficient than a half-load. Look for water usage
rates on the energy label. The most efficient machines are rated
G, the least A.
Pipe work insulation - ensure manufactured materials are both CFC
and HCFC free. Pipe lagging manufactured from recycled wool scrap
is also available.
PVC - is hotly debated as to its environmental suitability. There
are a number of alternatives to PVC pipe work systems.
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