Water supply systems

A rainwater tank (and other supplementary water supply systems) can be either:

• voluntarily installed
• required with a new house or commercial building where a local government has been approved to 'opt-in' to the relevant Queensland Development Code (QDC).

Find out more about voluntary installation requirements.

There are 2 QDC's for water supply systems and they apply to different types of buildings:

• Residential buildings – QDC 4.2 – Rainwater tanks and other supplementary water supply (PDF, 51KB)
• Commercial buildings – QDC 4.3 – Supplementary water supply systems (PDF, 70KB).

Where a property is located in a local government that has been approved to opt-in to the QDC, a rainwater tank or other supplementary water supply system must be installed with that new building.

In all other areas of Queensland, it is voluntary to install a rainwater tank or other water supply system (e.g. a greywater treatment plant).

Where a rainwater tank is included with a new house or building, it will be assessed as part of the building and plumbing applications.

A rainwater tank may also be subject to local government planning scheme requirements for siting and boundary setbacks to correctly locate it on the property. We recommend that you check with the relevant local government about any local requirements.

Installers of rainwater tanks and other supplementary water supply systems must comply with the health and safety requirements in the relevant QDC. A rainwater tank is typically installed by a licensed plumber. If building a new house, the builder may prepare some aspects for the installation of the tank during the construction of the home. For example, roof guttering and downpipes and the concrete slab for its base. A licensed plumber can be sub-contracted to complete its installation.

Local government opt-in requirements

A local government can apply to the Minister to opt-in to either or both QDCs. Where a local government is approved, the relevant QDC will apply to new buildings located on a property within a reticulated town water area.

For QDC 4.2 (residential buildings), the requirement will only apply to new Class 1 and 10 buildings (i.e. houses and their garages) and not multi-unit residential buildings (Class 2).

Read more about the history of water savings targets.

Requirements for new buildings

All building development applications lodged for new buildings to be constructed in an approved local government that has opted-in to the QDC must meet these requirements:

Residential buildings (Class 1 and 10)

For residential buildings, the following options can be installed to comply with the QDC:

• a rainwater tank
• an approved greywater treatment plant
• dual reticulation
• communal rainwater tanks
• stormwater re-use.

If you use a rainwater tank, there are minimum capacity and connection standards for the tank's installation:

• For a detached house, the tank must have a minimum capacity of 5,000 litres.
• For a non-detached house (such as terrace houses, townhouses and semi-detached houses), the tank must have a minimum capacity of 3,000 litres.
• All rainwater tanks must receive rainfall from at least half of the available roof catchment area or 100m², whichever is lesser.
• The tank must be connected to:
  • all toilet cisterns and washing machine cold water taps (for internal use)
  • at least one tap, typically a garden tap (for external use).
• An automatic switching device or a trickle top-up system may be needed to ensure a continuous water supply for internal fixtures supplied from a rainwater tank.

New residential buildings required to install a supplementary water supply system must also meet the minimum health and safety standards in QDC 4.2, including:

• measures to prevent insects and vermin entering or breeding in a tank
• measures to prevent contaminants entering the tank
• requirements for signage on tanks
• appropriate design and construction of stands and supports, openings and overflows.

Read Residential buildings – QDC 4.2 – Rainwater tanks and other supplementary water supply (PDF, 51KB) for detailed requirements for residential buildings.

Commercial and industrial buildings (Classes 3 to 9)

For commercial and industrial buildings, the following options can be installed to comply with the QDC:

• a rainwater tank
• a water storage tank
• a common tank
• an approved greywater treatment plant.

You need to meet minimum standards for installation and capacity, as well as water quality, health and safety.

Read Commercial buildings – QDC 4.3 – Supplementary water supply systems (PDF, 70KB) for detailed requirements for commercial and industrial buildings.

Applying to opt-in

A local government may apply to the Minister to opt-in to the relevant QDC. An application will be considered only when the local government can demonstrate that introducing the requirements have the potential to deliver a net benefit to the local community.

Refer to the Queensland Government's Guide to Better Regulation (PDF, 786KB) (May 2019) to identify whether the requirements would provide a net benefit to their community.

To apply:

1. Complete an application to opt-in to QDC (PDF, 60KB).
2. Submit the completed form to the address provided on the form with evidence that the proposal can provide a net benefit to the community.

The local government may also apply to vary some aspects in the applicable QDC, such as specifying the lots over a certain size or just to a part area in their local government.

Local governments approved to opt-in

Toowoomba Regional Council

Since 1 September 2014, rainwater tanks or other supplementary water supply systems have been required in the Toowoomba Regional Council area when a building development application is submitted for:

• some new commercial buildings
• a new single detached house on a lot more than 250m².

New houses

QDC 4.2 requirements apply only to new single detached houses (Class 1a(i) buildings) on properties more than 250m² in lot area.

The requirements do not apply to:

• detached houses on lots 250m² or smaller
• other new Class 1 buildings, including attached dwellings such as townhouses and villa units (Class 1a(ii)), and guest houses and boarding houses (Class 1b).

New commercial buildings

QDC 4.3 requirements apply to new commercial buildings, Class 5 to 9.

The requirements do not apply to Class 3 and 4 buildings, including:

• new motels and school dorm accommodation (Class 3)
• residences with a shop or an office (Class 4).

For more information, read the Building and Plumbing Newsflash 532 (issued 9 July 2014).

Gold Coast City Council (Pimpama–Coomera part area only)

On 5 June 2015, City of Gold Coast Council was approved to opt-in to MP 4.2 and MP 4.3 in the Pimpama–Coomera dual reticulation pipe network area only.

New houses and commercial buildings must be connected to the dual reticulation pipe network if they are on properties in the area covered by the network (installed as part of the Pimpama–Coomera Class A+ recycled water scheme).

They must be connected to the existing dual reticulation pipe network until the dual pipe network has been replaced with a single pipe network.

For more information, read the Building and Plumbing Newsflash 541 (issued 5 June 2015).

Southern Downs Regional Council

In November 2021, Southern Downs Regional Council was approved to opt-in to MP 4.2 and MP 4.3. water-saving requirements.

From 1 July 2022, all new residential and commercial buildings within the reticulated water network must have a rainwater tank installed as part of the build.

Tank requirements for new residential properties:

• roof collection area – collects water from at least 50% of the roof area or 100m² (whichever is lesser)
• plumbed to services – toilets, washing machines and at least one outdoor tap
• minimum capacity– 5,000 litres (1,100 gallons).

Tank requirements for new commercial properties:

• roof collection area – collects water from at least 50m² of the roof area
• plumbed to services – toilets (50m² per pedestal) and outdoor taps
• minimum capacity – 1,500 litres per required pedestal.

For more information, read the Building and Plumbing Newsflash 606 (issued 3 August 2022).