Alternative Water Sources
Efficient use of water and water conservation are key commitments of the Power and Water Corporation.
Fact sheets and booklets outlining water saving tips and conservation information are available at a number of outlets including our customer service centres and this website.
Alternative water sources such as greywater and rainwater tanks are not areas directly handled by Power and Water, however the following information aims to provide guidance and contact details for people seeking further information.
Greywater
Greywater includes wastewater from showers, baths, spas, handbasins, laundry tubs, washing machines, dishwashers and kitchen sinks. Greywater does not include wastewater from the toilet.
More than 60% of water used in Territory households goes into gardens. Greywater is able to be an alternative water source for gardens, however there are risks associated with its use and regulations that must be complied with.
Manual bucketing onto lawn and garden areas using water from the bathroom or laundry, or temporary use of a hose manually fitted to a washing machine outlet hose, is permitted in single domestic premises subject to the advice found on the Department of Health and Community Services website.
Greywater reuse systems vary greatly. Water from showers and baths generally are the lowest risk to reuse in the garden and also provide the best opportunity. The typical Territory household uses about 10 per cent of its water consumption in showers and baths. While many people are happy to use these systems, they are relatively expensive and not always well maintained.
Further information on greywater reuse in homes can be found on the Department of Health and Community Services’ website 60kb PDF.
All on-site wastewater systems require product approval from the Department of Health and Community Services before marketing, sale or installation in the Northern Territory. Visit the Department of Health and Community Services’ website 30kb PDF for more details.
For more information relating to greywater reuse in Alice Springs visit the Department of Natural Resources, Environment and the Arts website. 260kb PDF.
Rainwater Tanks
Requirements for connection of properties with rainwater tanks
Is Power and Water the approving authority for rainwater tank installations?
No, Power and Water is not the authority responsible for approving rainwater tank installations. The Department of Health and Community Services is the primary agency with responsibility for rainwater tanks – refer to Environmental Health Information Bulletin No. 7, ‘Requirements for the Use of Rainwater Tanks’ 45kb PDF.
If a property has a rainwater tank installed in addition to the water supplied by Power and Water, a backflow control device will need to be installed at the water meter.
Tanks may be subject to certain government requirements such as location, colour, height, noise control for pumping equipment, labeling of tank outlets and associated pipe work.
The Building Advisory Services section of the Department of Planning and Infrastructure can provide information on plumbing and building matters related to rainwater tanks.
For rainwater tanks in Central Australia, a building permit is not normally required if the tank is placed on a slab not more than 450mm above natural ground level. For coastal areas, structural design certification is required. Contact the Building Advisory Services section of the Department of Planning and Infrastructure for further information.
Does Power and Water subsidise the installation of rainwater tanks?
Power and Water does not subsidise the installation of rainwater tanks.
The Department of Natural Resources, Environment and the Arts provides a rebate of up to $500 to households in Alice Springs and Tennant Creek for plumbing services associated with the installation of an NT approved greywater diversion device and/or connection of a rainwater tank to the house (conditions apply).
What are Power and Water’s requirements in regard to rainwater tanks?
Where rainwater tanks are installed on a property where Power and Water already supply town water, the installation of a boundary containment backflow prevention device is required at the water meter. These devices shall be in accordance with the Rainwater Tank Design and Installation Handbook (HB230-2006) published by Standards Australia. The table below summarises the backflow prevention device requirements.
Type of Installation |
Hazard rating
|
Containment protection – Backflow prevention device
(at property boundary water meter) |
Individual or Zone protection backflow – Prevention device
(at connection point of rainwater control valve or tank top-up)
|
| Combined internal and external plumbing purposes |
| Underground (buried) rainwater tank (water tight) |
Medium |
Testable device |
Testable device or Registered Air Gap for rainwater top-up |
| Partly buried rainwater tank (water tight) |
Low |
Non-testable device |
Non-testable device or air gap for rainwater tank top-up |
| Aboveground rainwater tank (water tight) |
Low |
Non-testable device |
Non-testable device or air gap for rainwater tank top-up |
External plumbing purposes
|
| External hose taps and irrigation only. No connection of rainwater tank system to town water supply system |
Low |
No device required |
Not applicable |
Partly buried rainwater tanks are classified as those with inlet, overflow and all other openings at least 300m above finished ground level.
The following table outlines where Power and Water will fit a backflow prevention device.
| Type of Installation |
Residential |
Commercial
or Industrial |
DN20 or DN25
water meter |
Water meter larger
than DN25 |
| Combined internal and external plumbing purposes |
| Underground (buried) rainwater tank (water tight) |
|
|
|
| Partly buried rainwater tank (water tight) |
|
|
|
| Aboveground rainwater tank (water tight) |
|
|
|
External plumbing purposes
|
| External hose taps and irrigation only. No connection of rainwater tank system to town water supply system |
No device required |
No device required |
No device required |
| |
 Power and Water will provide a backflow prevention device at no cost |
 Subject to payment of applicable fees, Power and Water will provide a backflow prevention device |
 Property owner to supply and install backflow prevention device to Power and Water requirements |
Are there any other Power and Water requirements in regards to rainwater tanks?
Power and Water requires that rainwater tanks are not installed over water or sewer easements or other structures such as septic tanks. Any overflow from the tank must run to the stormwater system, not the sewerage system.
Who do I contact to have a backflow prevention device fitted?
For properties with an underground rainwater tank, it is the property owner’s responsibility to fit the required backflow prevention device. A licensed plumber with backflow prevention accreditation can install and commission the device.
Where Power and Water will provide a backflow prevention device (as per the table above), contact Water Services Land Development.
Can I use rainwater in my hot water system?
Use of rainwater in a hot water system is currently not recommended for two reasons:
- increased infection risk, and
- possible accelerated corrosion of the hot water service tank
Part B2 – Heated Water Services of the Plumbing Code of Australia requires:
Installations intended to supply heated water for human consumption, food preparation, food utensil washing or personal hygiene must be connected to a drinking water supply.
Rainwater is ‘soft’ (low alkalinity) and low in dissolved solids with a pH generally in the range 5 to 6. Anodes provided in hot water service tanks to minimise corrosion are typically available in three types to suit different levels of water hardness. If the anode isn’t matched to the hardness of the water flowing through the tank, then corrosion rates are likely to be much higher, leading to early failure of the hot water service.
For rainwater tanks with tank top up from the town water supply, water of different hardness is likely to be mixed in the rainwater tank, which presents specific challenges to anode performance. Advice should be sought from a licensed plumber.
How do I size a rainwater tank?
There are a number of different methods of sizing rainwater tanks, some more involved than others. Things to consider when sizing a rainwater tank are:
- cost of a rainwater tank and it’s associated installation costs,
- the volume of water required, for example, will the rainwater be used for toilet flushing and laundry or for irrigation,
- amount of rainfall and rainfall pattern,
- roof catchment and amount of guttering, and
- in areas where there are limited water supply options you may also need to consider security of supply. In such cases cost will be less of an issue.
Due to low rainfall in Central Australia, rainwater tank yield is relatively low compared to locations along the eastern seaboard. Recent modeling for Alice Springs indicates that average yield will be less than 25 kilolitres per household per year with a nine-kilolitre rainwater tank connected to a roof of 150m2. (Turner et al, 2007). Rainwater tanks in Alice Springs could reduce the reliance on reticulated water by approximately 5% when compared with the average household consumption of 535 kilolitres per year. ( 2005-06 National Performance Report Major and Non-Major Urban Water Utilities, WSAA)
Below are some examples of cost comparisons and potential water savings with regards to a number of water conservation methods, obtained from the Department for Natural Resources, Environment and the Arts 144kb PDF.
Water efficiency measure |
Cost |
Savings (KL/year) |
| Replace old showerhead with water efficient AAA rated model |
$40 |
25 |
| Replace old single flush toilet with an AAAA rated 4.5/3 L dual flush model |
$400
(installed) |
35 |
| Replace old top loader washing machine with more efficient AAA rated front loader |
$1000 |
30 |
| Fit 9 KL rainwater tank and pump connected to toilets |
$3,300
(installed) |
23 |
What do I have to do to maintain my rainwater tank?
It is important to maintain your rainwater tank and components to ensure they work effectively and supply high quality rainwater.
Regularly clean and check:
- roof and gutters,
- first flush devices,
- ensure insect screens are clear and free of leaves, debris and overhanging tree branches. If mosquitos are present, find out how they entered the tank and block their access, and
- the bottom and sides of your tank for sludge every two to three years. If sludge is present, you will need to either siphon the sludge out or empty the tank. Sediment in the tank may block your irrigation system or discolour your toilet cisterns and washing machine. Check the phone book for professional tank cleaners, if required.
For general guidance on the use of rainwater tanks visit
http://enhealth.nphp.gov.au/council/pubs/documents/rainwater_tanks.pdf 1mb PDF
For more information relating to rainwater tanks in Alice Springs visit
http://www.nt.gov.au/nreta/water/wise/pdf/rainwatertanks.pdf 93kb PDF
For information on a rainwater tank installation trial held in Alice Springs visit
http://csat.com.au/doc/CSAT_Rainwater_tank_trial_Factfile.pdf 159kb PDF
References
Turner, A., White, S., and Edgerton, N., (2007) Alice Springs Water Efficiency Study Stage III –
Implementation of the Alice Springs Water Efficiency Program - Feasibility Study - Final Report,
prepared by the Institute for Sustainable Futures, Sydney for the Northern Territory Government.
