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For plumbers and designers of in-house water installations
- to encourage them to conform to national trends in water
conservation.
For use by authorities - in formulating appropriate policies
on water efficiency in plumbing.
The Guidelines reflect the goals of the Australian Water
Industry in its efforts to conserve water by ensuring that
in-house plumbing incorporates the best technology in water-use
efficiency.
The purpose is to indicate desirable criteria for water-use
rates and characteristics.
It is now clear that modern, extremely efficient water-saving
fittings provide service equal or superior to their inefficient
ancestors.
New products and techniques allow today's households to use
a third less water than those of a decade ago, without sacrificing
comfort or changing lifestyles. However, water consumption
per person is increasing.
The authorities are well aware that the water-use appliance
industry itself is the best suited to know and to cater for
consumer preferences and to develop and utilize water-efficient
technologies. However, initiative in water conservation would
also be expected to come from the public sector, namely the
authorities, assigned the task of water resource planning
and maintenance.
¹. Woodwell J.C. "Water Efficiency - alternative to US $1
billion dam" WWI Journal, October 1989.
². Commonwealth of Australia "Personal Action Guide for the
Earth", July 1989.
Criteria for in-house water-using appliances and plumbing
Better technology needs to be developed and used for more
water-use efficient design associated with the following items
:-
- Shower heads
- Water Taps and Tap Aerators
- Dishwashers
- Clothes Washers
- Water Closets
- Urinals
- Sinks, Basins and Baths
- Water Plumbing Systems - Cold and Hot
- Domestic Garden Sprays
- Water Pressure Reduction and Inline Flow Restrictors
- Greywater reuse
- Evaporative Coolers.
Appliance Labelling Scheme
A scheme to recognize water-use efficiency through the rating
and labelling of manufacturers' appliances is administered
by Standards Australia. The scheme is voluntary and is intended
to help consumers assess the water-use efficiency of household
appliances before they buy.
The present scheme caters for three ratings :- A, AA and
AAA.
- A For an acceptable level of water efficiency.
- AA High water-use efficiency, notionally 25 percent less
water-use that for the A rating.
- AAA Excellent water-use efficiency, notionally 25 percent
less water-use than AA.
For instance, a shower rose using 12 litres of water per
minute would receive an 'A' rating because its water-use rate
does not exceed that of the Standard for water-efficient shower
heads. A shower rose using 9 litres per minute would receive
an 'AA' rating and one using 6.75 litres per minute would
receive an 'AAA' rating.
Standards Australia has issued Miscellaneous Publication
SAA MP64 - 1992 "Manual of Assessment Procedure for Water
Efficient Appliances" with specifications for Shower Heads,
Dishwashing Machines, Clothes washing Machines, Urinals and
Water Taps. Specifications for other products such as water
closets will be added when water efficient ratings can be
determined.
Initial requests for labelling should be forwarded in writing
to the Quality Assurance Services Department of Standards
Australia, listing each product, its model and catalogue identifications,
proposed applications, methods of operation and rating claim.
Manufacturers and distributors of water-using appliances
are urged to support the scheme to assist water authorities
to defer the need to augment water supply systems.
Keen acceptance of this scheme will enhance market awareness
of water efficient products.
The appliances which follow are commented on with respect
to their present water-using status and their potential with
regard to water-use efficiency.
1. Shower Heads
The shower is the highest user of water in the bathroom but
the shower head has, until recently, been designed without
restriction of flow rate as a consideration.
With the new common use of mains-pressure water heaters the
result has been over-use of both water and heating energy.
An average of 30.3% of in-house water-use was attributed to
the shower in the Perth (1985) Study Report and :-
Shower heads fall into two basic groups
- those for gravity-fed systems
- those for mains-pressure systems.
The greatest water wasting occurs when a gravity-type head
is used in a mains pressure system.
The technology of using flow restrictors (washers with a
small hole in the middle) can cause poor shower quality and
performance if not matched with an appropriate shower rose.
A properly-balanced water flow is more achievable when flow
restrictors are put in both hot and cold taps. Energy-saving
is closely related to water saving.
The present situation
In Australia, the maximum flow rate specified is 12 litres
per minute. In the USA and Europe, a maximum efficient rate
of 8 to 9L/m and a standard of 12L/m are the practice. Less
than 5L/m is not considered sufficient for an adequate shower.
That Standard discharge rate relates only to one particular
pressure. Water Efficient shower heads are already manufactured
and sold, therefore no fundamental development research will
be necessary. Shower heads are available that maintain a quality
of service at low rates of flow. They vary in "feel" from
misty to needle-like, from pulsating to a vigorous pounding
flow. In addition, volume-control valves on the shower head
enable the user to reduce or shut off the flow in midstream
while maintaining a balanced mix of hot and cold water.
Water-use efficient ratings for Standards Australia's Water
Conservation Labelling Scheme are :-
- A 12.0L/m to more than 9.0L/m
- AA 9.0L/m to more than 6.8L/m
- AAA 6.8L/m or less.
2. Water Taps
In-house water use occurs under a number of categories; eg.
kitchen, bathroom, laundry; however the common denominator
in many situations is the tap. Taps come in many forms from
the traditional loose jumper valve variety, to ceramic discs
and sophisticated electronic devices activated by sensor.
Each tap may offer a different advantage, eg. economy, ease
of use, greater hygiene, however, because they are all required
to control the delivery of water their design and operation
is often a key factor in water-use efficiency.
The present situation
Water-use efficient ratings for Standards Australia's Water
Conservation Labelling Scheme are :-
- A Tap with a positive reliable seal and aerator
- AA As for A, plus adjustable single lever/handle control
incorporating an automatic flow-reducing feature
- AAA As for A, plus electronic or automatic self-closing
feature.
3. Dishwashers
Most dishwashers are of similar size, ie. for 12 to 14 place
settings. There is already a number of machines giving adequate
performance without excessive water or power use.
As is the case for clothes washers, the ideal would be a
package of both water and power use efficiency, clearly stated
in terms of dollar savings to the buyer.
Water-use efficiency ratings for dishwashers under Standards
Australia's Water Conservation Labelling Scheme are, per program
run :-
- A More than 24L and not more than 32L
- AA More than 18L and not more than 24L
- AAA Not more than 18L.
4. Clothes Washers
There is a great variety of machines available. It is intended
to encourage the manufacture and use of those with the lower
water-use per kilogram of clothes.
Generally, those that use less water also use less electrical
power. This would be improved by additional encouragement
that consumers required the suds-saving feature as well.
Water-use efficiency ratings for clothes washers under Standards
Australia's Water Conservation Labelling Scheme are, per dry
kg. of clothes :-
- A More than 24L and not more than 32L
- AA More than 18L and not more than 24L
- AAA Not more than 18L.
5. Water Closets
Prior to regulation or consumer education on water-wise toilets,
it was found that in Melbourne, water for flushing toilets
was 18% of the total residential water use and that the average
water use in Perth for toilet flushing was 32% of total in-house
water use (i.e. 18.5% of total residential water-use) second
after the total bathroom usage at 38.7%.
Significant savings have already been made by the use of
dual flush and reduced flush cisterns in Australia and overseas.
Australian water authorities, while mindful of the need for
sufficient flushing of gravity sewers, will support significant
reduction in present flush quantities. Manufacturers need
to develop pans designed for effective cleansing and clearing
with reduced flush.
6. Urinals
Water-use saving for urinals using demand-flushing instead
of cyclic flushing has been estimated to be from 30% up to
more than 80%, mainly effective in the high-rise office blocks
in the central business districts of cities.
Few overseas or Australian studies have extended to water-use
efficiency through the use of appropriate urinals and their
flushing systems.
7. Sinks, Basins, Baths
Where water is retained for use in certain fixtures, clearly,
long-term wastage can occur where the container is bigger
than necessary. In many cases now, sensible design has reduced
this waste already, but relevant industry standards do no
exist.
8. WATER PLUMBING SYSTEMS - COLD AND HOT
The principal causes of water wastage from property plumbing
systems are
- leakage, mainly undetected below ground, but also through
dripping taps and toilet cisterns
- drawoff while waiting for the hot supply to reach operating
temperature.
The present situation
AS3500.1 has generally increased pipe sizes to limit velocity
and to minimise wear and water hammer.
Hot water drawoff wastage factors are recognised as :-
- remote location of water heater
- water run during warm-up of some instantaneous heaters
- low or high pressure schemes, determining pipework size
- pipework configuration, where to branch to offtakes
- use of recirculating hot water
- need for insulation of pipework
- water temperature settings too high
- oversized pipework.
- Investigations by CSIRO have included measuring the heat
losses from hot water pipes due to draughts. Heat losses
were measured at a range of velocities using a low-speed
wind tunnel to provide a closely controlled environment.
9. Domestic Garden Irrigation
Watering of domestic gardens is known to account for the
greatest use of scheme water in residential areas. In the
Perth "Domestic Water Use" study (1985) it was found that
47% of the average domestic scheme water use per household
was ex-house, of which 91% was for irrigation. For Melbourne,
38% of average domestic use is ex-house.
10. Water Pressure Reduction
Urban water supply pressures in Australia are claimed to
be among the highest in the world. On average, they are certainly
higher than those in the U.K. and many European countries.
Past studies have identified excessive water pressure as a
contributing factor in water wastage.
Some forms of water-use such as showering, rinsing and car
washing are largely time dependent. Unnecessary consumption
can occur in high pressure areas where consumers use more
water than is required simply because the tap is turned on
a certain amount and the resulting flow is in excess of requirements.
There is potential to reduce consumption by reducing supply
pressures.
Pressure reduction can be carried out on a district basis
in distribution systems or at individual properties.
Pressure reduction within an authority distribution system
has the advantage of also reducing the rate of leakage and
extending the working life of the system.
A more flexible method of pressure reduction is by the installation
of suitable devices on the service pipes to individual properties.
For this purpose, three types of valves are available :- pressure
reduction valves (PRV's), pressure limiting valves (PLV's)
and pressure ratio valves.
PLV's and pressure ratio valves are cheaper, a typical domestic
quality 20 mm valve costs about $60. These are usually non-adjustable
and are designed to limit outlet pressures to within a certain
range depending on inlet pressure and the nominal set pressure
but are not fail-safe.
PLV's and pressure ratio valves, while relatively cheap,
are able to be tampered with and are not fail-safe.
PRV's are more expensive, costing around $120 for a 20 mm
size, are often adjustable and will reduce outlet pressures
to a predetermined value.
Both PLV's and pressure ratio valves have limited service
life which, depending on the quality of the valve and the
water supply, is in the order of 5 to 10 years.
Pressure reduction on individual properties can lead to unacceptable
noise levels.
11. Greywater Re-use Systems
Water re-use through greywater systems comes under two categories
- commercial and domestic. In general the systems collect,
filter and store household effluent from baths, showers and
basins for re-use in toilet flushing and garden watering.
Some systems include disinfection. Kitchen effluent re-use
is probably not advisable because of the high level of fat
and food particles.
Public acceptance of recycling for toilet flushing has been
achieved in Europe, USA and Japan. The potential for greywater
re-use in Australia is great, particularly in arid and remote
areas for domestic use, as well as commercial, (motels, etc.)
12. Evaporative Coolers
Optional ways to operate an evaporative air cooler include
:-
(a) treating cooling water and recycling it,
(b) discharging a portion of the cooling water continuously
without treatment, or
(c) automatically dumping water when salt content becomes
excessive.
- Option ( a ) can be costly and a problem in disposal of
treatment by-products
- Option ( b ) usually results in a cleaner flow of water
for disposal
- Option ( c ) has been claimed as the most water-use efficient
method.
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