INFO 026 Requirements for installation of rainwater tanks

Toowoomba Regional Council requires mandatory rainwater tanks and water saving measures on new dwellings and commercial buildings. The Queensland State Government granted this request to start from 1 September 2014. Queensland Development Code (QDC) 4.2 is now applicable to any new class 1 (a)(i)buildings (single detached dwellings) on blocks greater than 250m2. Dwellings on blocks less than 250m2 are exempt. Queensland Development Code 4.3 is applicable for any new commercial buildings (class 5 to 9).

Please note that units are exempt.

As the definition of units is unclear in the Building Code of Australia (BCA), Council considers the definition to be as defined in BCA Volume One Part 3 A3.2 Classifications Class 1a (ii) - one of a group of two or more attached dwellings each being a building separated by a fire-resisting wall, including row house, terrace house, town or villa.

What are the requirements for mandatory rainwater tanks?

Requirements applying to a new house: refer to QDC MP 4.2

  • Roof collection area - collect water from at least 50% of the roof area or 100m2 (whichever is lesser)
  • Plumbed to service - toilets, washing machine, at least one outdoor tap
  • Minimum capacity
    • 5,000 litres (1100 gallons) (where the site has an area or 250m² or more)
    • 45,000 litres (in a rural zone and only where no reticulated water is available and connected in the rural residential zone)

Requirements applying to class 5-9 buildings:

  • Roof collection area - collect water from at least 50m2 of the roof area
  • Plumbed to service - toilets (50m2 per pedestal) and outdoor taps
  • Minimum capacity - 1,500 litres per required pedestal - refer to QDC MP 4.3

The approval of mandatory rainwater tanks will be issued as part of the overall plumbing approval for any new residential or non-residential building(s).

Ensure you check the location of any Council sewers, storm water or water mains on your allotment (refer to Queensland Development Code MP 1.4). These may affect where you can site your rainwater tank.

Overflow from rainwater tanks needs to be discharged so as not to cause nuisance to neighbours or erosion of land. Acceptable points for overflow discharge may include a bubbler 3m on downside of all buildings and 3m from property boundaries, or discharge into an existing Council-approved stormwater drainage system inter allotment/street channel.

sign rainwater

Marking and signage:

In addition to the marking requirements (Clause 2.2 AS 3500 1.2003) the water supply system from a rainwater tank shall be clearly marked at intervals not exceeding 500mm with the word "RAINWATER' in contrasting colour, in accordance with AS 1345. Water outlets shall be identified as 'RAINWATER' or with a rainwater tap identified by a green coloured indicator with the letters 'RW'. A typical sign is shown below.

Tank signage notes come from AS 3500 and as per Queensland Development.

What requirements apply to the connection of mandatory rainwater tanks?

There are a range of plumbing requirements which must be adhered to in the installation of mandatory rainwater tanks.  To assist those involved in tank installation Council has prepared four standard drawings (see bottom of page) illustrating the preferred means of connecting mandatory rainwater tanks. These are as follows:

  • Figure 1 mandatory rainwater tank above ground installation - trickle top up
  • Figure 2 mandatory rainwater tank above ground installation - automatic switching device
  • Figure 3 mandatory rainwater tank above ground installation - with trickle top up - back flow prevention required
  • Figure 4 mandatory rainwater tank above ground installation - automatic switching device

Important note: Council stresses there are health concerns relating to the drinking of rainwater.  It is recommended that rainwater is disinfected.  If you intend using rainwater for drinking, boiling is the most traditional form of disinfection.  Ultra Violet (UV) under-bench disinfection systems are becoming popular. However, organic matter can coat the UV light and affect its operation.

Cleaning and maintenance of your tank is important. The following tips for cleaning and maintaining your rainwater tank are suggested: At least every 3-6 months, as the following describes:

Gutters: Inspect and clean making sure that they are free from leaf materials and other debris. If large amounts are found, then inspection and cleaning should be done more frequently, especially after heavy rainstorms. Gutters must be graded evenly to down pipes. Low spots where water accumulates not only deteriorate gutters but also contaminate the water.

Roof: Check and clear away accumulated debris including leaf and other plant materials. Overhanging branches should be pruned back. TV antennas attract birds and therefore should not be above the roof area that contributes water to your tank due to bird faeces contamination.

Tank inlets, mosquito/insect proofing and leaf filters: Check, clean and repair if necessary.

Mosquito and insect screens: These are required to be fitted to all inlets and outlets, and down pipes that hold water. The screen gauze must be a diameter not coarser than 1mm aperture mesh.

Roof gutter screens: To prevent leaf litter and other debris from blocking screens and collecting in the tank it is recommended that gutter guards be used.

Tank and tank roof: Check structural soundness of tank including the roof and access cover. Holes and gaps must be repaired.

Pipe work: Check for structural soundness. Make sure that drains are not blocked.

Internal inspection: Check for evidence of access by animals, birds or insects including the presence of mosquito larvae. Find and close points of access. Also check for evidence of algal growth. Find and close all points of light entry.

First flush devices, rain heads and filters: Check and clean and repair or replace if required. First flush devices need to be cleaned regularly to function well.

Pump and pressure unit: Keep pumps clean and ventilated.  Protect from weather and corrosion.  A good quality pump should give many years of trouble free service.  Insist on a quality pump unit and pressure unit.  Cheap units will be costly and disappointing in the long term.

Noise control: To minimise noise ensure the pump is designed with a minimum sound power rating and is housed and sited to minimise environmental noise impact.  Submersible bore pump pressure systems are very quiet and can be used for tanks.  This may eliminate the need for pump housing.

Overflow: Tank overflow pipes should be vermin proof and discharge in accordance with Council requirements.

Extraction point: The extraction point should be above the tank floor to ensure that water is of good quality.  The bottom water zone is where particles settle and is anaerobic and often contains more micro-organisms.

Roofing materials: Most modern roofing materials are safe for rainwater collection but check on your roofing finish and flashings. Lead flashings must not be used where rainwater collection is proposed.

Inside of tank: Check for presence of accumulated sludge and clean out if necessary.  Remember not to discharge dirty water into a stormwater drain or onto a road. Run the water onto your lawn.  Small amounts of sludge can be buried in your garden.  Large amounts should be taken to the Toowoomba Waste Management Centre.  Alternatively, you can locate a professional tank cleaning company through the Yellow Pages.  Certain tanks may have specific maintenance considerations.  For example, it is important not to damage the protective internal polymer coating on certain tanks.  Check with the manufacturer for your tank’s maintenance requirements.

More information

For further specific information on the requirements for the installation of rainwater tanks please contact the following relevant branches on 131 872:

  • Plumbing requirements for installing rainwater tanks: contact Development Services – Plumbing Team
  • Water demand management section: contact Water Service - Waterwise
  • Building requirements: contact Development Services - Building Compliance

Disclaimer

The information contained in this page is a guide only. This information has been prepared by Toowoomba Regional Council to help people gain an understanding of the Toowoomba Regional Councils and Queensland Development Code 4.2 and 4.3 requirements. 

Click on the images below to enlarge

Figure 1 - Rainwater tank above ground installation – trickle top up

rain water tanks figure 1

Figure 2 - Rainwater tank above-ground installation automatic switching device

rain wate rtanks figure2 

Figure 3 - Requirements for mandatory tanks (below ground) on new dwelling – trickle top up

rain water tanks figure 3 

Figure 4 - Requirements for mandatory tanks (below ground) on new dwelling – automatic switching device

rain water tanks figure 4

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