NCC 2022 Volume Three - Plumbing Code of Australia

B6

Part B6 Rainwater services

Part B6 Rainwater services

Introduction to this Part

This Part sets out the requirements for any part of a rainwater service from the point of connection of the rainwater storage, to the rainwater points of discharge.

This Part applies to a rainwater service supplied by stored rainwater collected from a roof, where a separate cold water service is provided for drinking and personal hygiene from a Network Utility Operator's supply.

This Part does not apply to rainwater used only for irrigation purposes.

Where water provided by a Network Utility Operator is not available or not utilised as the primary water source for drinking and personal hygiene, roof collected rainwater is considered to be a cold water service supplied by an alternative source.

Objectives

The Objective of this Part is to—

  1. safeguard people from illness, injury or loss (including loss of amenity) due to the failure of a rainwater service; and
  2. conserve water; and
  3. safeguard the environment; and
  4. safeguard public and private infrastructure; and
  5. ensure that a rainwater service installation throughout its serviceable life will continue to satisfy the requirements of Objectives (a) to (d).

Functional Statements

A rainwater service must be designed and installed so as to operate in a way that avoids the likelihood of inadvertent contamination of any drinking water service and minimises any adverse impact on building occupants, the Network Utility Operator’s infrastructure, property and the environment.

Performance Requirements

The points of discharge of a rainwater service must—

  1. have—
    1. a working pressure of not less than 50 kPa; and
    2. a static pressure within a building of not more than 500 kPa; or
  2. have water pressures suitable for the correct functioning of the fixture or appliance where water pressures outside of (a)(i) and (a)(ii) are required.

A rainwater service must ensure pipework water velocity does not exceed 3 m/s for more than 1% of the time that the water is required during the normal peak flow.

Explanatory information

During the hour of heaviest usage in reticulated rainwater service pipework, a velocity of 3 m/s must not be exceeded for 99% of the time that any downstream fixture is in use.

A rainwater service must ensure the efficient use of water by—

  1. limiting water usage from—
    1. a cistern or flushing device for a urinal, to a flush volume of not more than 2.5 litres for each—
      1. single urinal stall; or
      2. 600 mm length of a continuous urinal wall; and
    2. a dual flush cistern or flushing valve that is connected to a water closet pan, to a flush volume of not more than—
      1. 6 and 3 litres; or
      2. 4.5 and 3 litres; and
    3. other rainwater using fixtures and appliances, to an efficient level; or
  2. other water saving measures which achieve equivalent or greater efficiency than (a).

Applications

The flush volumes of B6P3 may be within a tolerance of—

  1. ±0.5 litres for the full flush of a 6/3 litre cistern; or
  2. +0.5 litres for the reduced flush of a 6/3 litre cistern; or
  3. ±0.2 litres for a 4.5/3 litre cistern.

Exemptions

The requirements of B6P3(a)(ii) do not apply to a vacuum drainage system.

  1. A rainwater service must ensure access for maintenance of mechanical components and operational controls.
  2. A rainwater service must ensure the system, appliances and devices can be isolated for testing and maintenance.

Pipes and pipe outlets that form part of a rainwater service must be clearly identified.

A rainwater service must avoid the likelihood of failure and uncontrolled discharge.

NCC Blurbs

A rainwater service must—

  1. avoid the likelihood of contamination of water within the rainwater service, the cold water service, or the Network Utility Operator's drinking water supply (if connected); and
  2. not pose a hazard to public health; and
  3. not have an unprotected cross-connection with any Network Utility Operator's drinking water service.
NCC Title

Rainwater service

NCC State
VIC
NCC Variation Type
Insertion
NCC SPTC Current
Rainwater service

Deemed-to-Satisfy Provisions

(1) Where a Deemed-to-Satisfy Solution is proposed, Performance Requirements B6P1 to B6P6 are satisfied by complying with B6D2 to B6D6.

VIC B6D1 Deemed-to-Satisfy Provisions2019: B6.1

Delete subclause B6D1(1) and insert B6D1(1) as follows:

(1) Where a Deemed-to-Satisfy Solution is proposed, Performance Requirements B6P1 to B6P7 are satisfied by complying with B6D2 to B6D6.

(2) Where a Performance Solution is proposed, the relevant Performance Requirements must be determined in accordance with A2G2(3) and A2G4(3) as applicable.

NCC Blurbs

A rainwater service must comply with Section 15 of AS/NZS 3500.1. Additionally, after Clause 15.3.3(c) insert (d)—

(d) For Class 1 buildings and extensions or additions to Class 1 buildings the following applies.

Where a water service from a rainwater tank interconnect with a water service from a water main supply, the supply to a fixture, appliance or water outlet shall be maintained by a device/mechanism that facilitates a seamless automatic switching from one water service supply to another and vice versa without the need for manual intervention.

NCC Title

General requirements

NCC State
SA
NCC Variation Type
Replacement
NCC SPTC Current
General requirements
NCC Blurbs

A rainwater service must comply with Section 15 of AS/NZS 3500.1.

Notes

The Victorian NCC 2019 rainwater tank variation (VIC V2.6.1 and V3.12.0 respectively) remains in effect until 30 September 2023 after which the following takes effect:

A rainwater tank must be installed in a Class 1 building in accordance with the regulations made under the Building Act 1993 (Victoria).

See Part B7 clause B7D4.

NCC Title

General requirements

NCC State
VIC
NCC Variation Type
Replacement
NCC SPTC Current
General requirements

A rainwater service must comply with Section 15 of AS/NZS 3500.1.

Identification of rainwater pipework and outlets must be in accordance with Section 15 of AS/NZS 3500.1.

(1) Cisterns or flushing devices for water closet pans must—

  1. be a minimum of 3 Star WELS rating, discharging not more than 6 litres or 4.5 litres for a full flush; and
  2. have a dual flushing mechanism.

(2) Cisterns or flushing devices for urinals must—

  1. be a minimum of 2 Stars WELS rating, discharging not more than 2.5 litres; and
  2. serve a single stall or 600 mm length of continuous urinal wall; and
  3. not be automatic or set-cycle.

Applications

The flush volumes of B6D4 may be within a tolerance of—

  1. ±0.5 litres for the full flush of a 6/3 litre cistern; or
  2. +0.5 litres for the reduced flush of a 6/3 litre cistern; or
  3. ±0.2 litres for a 4.5/3 litre cistern.

Exemptions

  1. The requirements of B6D4 do not apply to a vacuum drainage system.
  2. The requirements of B6D4(2)(c) do not apply to a programmed solenoid operated flushing system if programmed to shut down during extended periods of non-occupancy of a building.

Explanatory information

  • Prior to installing a programmed solenoid operated flushing system, further advice should be sought from the authority having jurisdiction.
  • Where sensor control is used for urinal flushing, sensors should be located to avoid unnecessary ‘nuisance’ flushing triggered by pedestrian traffic.
  • AS/NZS 6400 Water Efficient Products - Rating and Labelling, provides the basis for the rating and labelling of a range of products under the mandatory Water Efficiency Labelling and Standards (WELS) scheme.
  • B6D4 Water efficiency outlines the minimum level of water efficiency for certain plumbing products and fixtures, however the adoption of greater efficiency products and technologies should be considered.

(1) Access for maintenance of mechanical components and operational controls must be provided in accordance with AS/NZS 3500.1.

(2) Isolation of appliances and backflow prevention devices for testing and maintenance must be provided in accordance with AS/NZS 3500.1.

A rainwater service in a designated bushfire prone area must be in accordance with AS 3959.