Is a rainwater tank required for a new house in SA?

What the Building Rules now say about rainwater tanks

MBS 007, Modifications to the Building Code of Australia 2022 edition, is a Ministerial Building Standard published by the Minister for Planning. Clause 2.2.7 of Amendment 6 (April 2026) reads: “Modify SA Part H9 Water efficiency to read as follows: This clause has deliberately been left blank. SA Part H9 does not apply in South Australia.” Clause 1.6 states that the modifications “apply to the Building Code from the date of gazette and must be read as if they are consolidated into the Building Code.”

The same clause 2.2.7 appears in Amendment 5 (December 2025), whose list of changes includes “Remove SA rainwater tank provisions that no longer apply.” PlanSA’s Building Code page, as archived on 2 March 2026, describes Amendment 5 as removing “redundant rainwater tank provisions” and states that it “was gazetted on 18 December 2025.”

In the next edition, the ABCB’s NCC 2025 Volume Two records that “The content of SA Part H9, which exists in NCC 2022, has been removed.” For the Building Code of Australia volumes, clause 1.5 of MBS 007 gives 1 May 2027 as South Australia’s NCC 2025 adoption date. The ABCB separately lists 1 May 2026 for the Plumbing Code of Australia, Volume Three.

• NCC 2025 in South Australia: which edition applies

Why older pages still say a tank is required

The SA.GOV.AU rainwater tanks page, last updated on 5 December 2023, states: “South Australian building rules require that new dwellings and some extensions or alterations, have an extra water supply.” That page predates MBS 007 Amendments 5 and 6, and pages that repeat it describe the earlier position.

The earlier additional-water-supply provisions sat in SA Part H9 of NCC 2022 Volume Two. Performance Requirement SA H9P1 called for an additional water supply “plumbed to at least a water closet or a water heater or all the cold water laundry outlets”. As published by the ABCB, clause SA H9D2(1) limited SA H9P1 to applications designated under the Regulations “as HomeBuilder grant development”, subject to further conditions. Clause SA H9D3(1) addressed roof catchments of not less than 50 m² with a tank of not less than 1 kilolitre, and SA H9D3(2) addressed smaller catchments. MBS 007 now states that SA Part H9 does not apply in South Australia.

Rainwater tanks in planning consent: the Stormwater Management Overlay

The Planning and Design Code (Version 2026.19, in effect 8 October 2026) contains a Stormwater Management Overlay. Its Desired Outcome DO 1 reads: “Development incorporates water sensitive urban design techniques to capture and re-use stormwater.” Performance Outcome PO 1.1 asks that residential development be designed to capture and re-use stormwater to conserve water, manage peak runoff flows and volume, and manage runoff quality.

The overlay’s Deemed-to-Satisfy Criteria / Designated Performance Feature DTS/DPF 1.1 covers detached, semi-detached or row dwellings, fewer than 5 group dwellings, co-located housing or dwellings within a residential flat building, and lists criteria that must all be met (“satisfies all of the following”). In summary, it describes rainwater tank storage connected to at least 60% of the roof area for a detached dwelling (not in a battle-axe arrangement), semi-detached or row dwelling, and 80% in all other cases; “connected to either a toilet or laundry cold water outlets for sites less than 200m2”; “connected to one toilet and the laundry cold water outlets for sites of 200m2 or greater”; a minimum total capacity set by Table 1; and, “where detention is required”, a 20–25 mm slow release orifice. It also requires that the development “incorporates dwelling roof area comprising at least 80% of the site's impervious area”.

Table 1 sets minimum retention volumes of 1000 litres, 2000 litres and 4000 litres against site-size rows labelled “<200”, “200-400” and “>401” m², with detention volumes that depend on site size and perviousness; a boundary case is confirmed with the relevant authority. A DTS/DPF is one way a proposal can satisfy PO 1.1, and the overlay is relevant only where it applies to the property. The zones and overlays for an address, and how they are applied, are confirmed with the council.

• What to check before buying land in Adelaide

Where the rainwater tank goes: what the site plan shows

Schedule 8 clause 2 of the Planning, Development and Infrastructure (General) Regulations 2017 (version 17.9.2026) applies to “An application for planning consent that proposes building work not within the ambit of Schedule 8 clause 1 or 3”. Clause 2(1)(a)(xi) requires the site plan for such an application to show “the location and capacity of any proposed water tank, the connection type, the total roof area to be connected to the tank and the proportion of the tank to be used for retention or detention”.

Where a tank is proposed, those items fix it on the drawings together with the roof area that drains to it, for assessment by the relevant authority. Address-specific planning requirements are confirmed with the council; building rules consent may be granted by a private certifier.

• What a building documentation set contains
• New build services

If a tank is installed: the plumbing rules

Clause SA B6D2 of NCC 2025 Volume Three, the Plumbing Code of Australia that the ABCB lists South Australia as adopting from 1 May 2026, requires a rainwater service to comply with Section 15 of AS/NZS 3500.1 with a South Australian variation. Variation (d) addresses Class 1 buildings and extensions or additions to them: where drinking water is used to top up a rainwater tank or supplement a rainwater service, “it shall be maintained by an automatic change-over device, automatic top-up device or a device/mechanism that facilitates an automatic switching without manual intervention.”

SA.GOV.AU’s certificates of compliance page lists “installing an alternative water service” among the plumbing work for which a plumber must give an electronic certificate of compliance. Where tank overflow is piped to the stormwater system, clause 3.3.5(a) of the NCC 2022 Housing Provisions requires the position and manner of discharge to be “to the satisfaction of the appropriate authority.”

• Home extensions in Adelaide