NCC 2022 Volume Three - Plumbing Code of Australia
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Classification
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Classification
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B5

Part B5 Cross-connection control

Part B5 Cross-connection control

Introduction to this Part

This Part sets out cross-connection hazards and corresponding Hazard Ratings.

Objectives

The Objective of this Part is to—

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

Functional Statements

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

Performance Requirements

Water services must be designed, constructed and installed to avoid contamination.

Applications

B5P1 applies to cold water, heated water, non-drinking water and fire-fighting water services.

Verification Methods

(1) Compliance with Performance Requirement B5P1 for individual protection and zone protection is verified by compliance with B5V1.

(2) A hazard exists wherever it is possible for water or contaminants to enter a non-drinking water service or supply via any potential cross-connection between itself and another separate non-drinking water service on the same site.

(3) Each hazard must be—

  1. assigned a Hazard Rating in accordance with (4); and
  2. isolated from the drinking water service by an appropriate backflow prevention device which is selected and installed for the appropriate Hazard Rating in accordance with Section 4 of AS/NZS 3500.1.

(4) To determine the Hazard Rating—

  1. an assessment of the property or proposed installation must be undertaken using Tables B5V1a, B5V1b, B5V1c, B5V1d and B5V1e; and
  2. the scores allocated from each table are calculated; and
  3. the Hazard Rating is determined by the sum of the scores in accordance with B5V1(5).

(5) A total score of—

  1. 0 to 3 presents no Hazard; and
  2. 4 to 7 presents a Low Hazard; and
  3. 8 to 10 presents a Medium Hazard; and
  4. 11 or greater presents a High Hazard.

(6) Notwithstanding the Hazard Rating determined in (4), where access to the site is restricted in a way that could limit or prevent future testing or maintenance of a backflow prevention device, the site must be protected with a containment device suitable for a High Hazard.

Explanatory information

Table B5V1a Building class
Site condition Common examples Notes Score
The property to which the water service is installed contains a Class 1, 2, 7a, or 10 building where not more than 12 people reside. Domestic residences and carparks with no associated activities. Building may use small amounts of cleaning products, etc. 1
The property to which the water service is installed contains a Class 3, 4, 5, 6 or 7b building where chemical products are not stored. Hostel, hotel and multi-level office. Building is likely to have greater than 12 residents and/or occupants, and may contain moderate amounts of cleaning or commercial chemicals. 2
The property to which the water service is installed contains a Class 7b, 8 or 9 building where chemical products are stored. Mechanical workshop, metal finisher, cleaning product wholesaler. May contain large amounts of hazardous or toxic commercial chemicals. 3
Table B5V1b On-site water services
Site condition Common examples Notes Score
There is only a drinking water supply and no other water sources to the property. The drinking water source may be a rainwater tank connected to a detached dwelling. Residential rainwater tanks are considered drinking water. 0
There is one drinking water supply and potentially other non-drinking water supplies or a separate fire-fighting water service available to the property (not applicable if the non-drinking water supply is Network Utility Operator provided recycled water with a sewerage source). Network Utility Operatordrinking water supply and a separate fire water service. Network Utility Operator supplied recycled water with a sewerage source is assessed separately due to greater health risks. 3
Commercial agriculture, farming, turf irrigation, industrial, processing or chemical industries. The property is supplied with drinking water and non-drinking water from multiple sources with potential for health related contamination. Property has a Network Utility Operator drinking water source and an on-site wastewater effluent irrigation system, process water or bore water source. Increased potential for cross-connection between drinking water and non-drinking water with high consequences such as chemicals, recycled sewerage, medical or biological contaminants. 5
Table B5V1c Drinking water use
Site condition Common examples Notes Score
Drinking water use will not involve commercial use of hazardous or toxic substances and the site is unsuitable for their use and unlikely to change. Domestic residences, offices and restaurants. Minor use of cleaning and other chemicals is permitted. Professional or commercial hazardous chemical use is not permitted. 1
Drinking water will be used with commercial use hazardous substances, but not Schedule 1 to 4 or Schedule 6 to 8 poisons. Drinking water may be used with commercial use hazardous substances without major modification. Butchers, hairdressers. Hazardous substances and scheduled poisons have applicable warning labels. Cleaning of floors and benches with chlorine solution puts butchers into this category. 2
Drinking water use may involve large scale food or beverage processing, human or animal biological or faecal matter, Schedule 1 to 4 and Schedule 6 to 8 poisons and have potential for contamination. The installation is suitable for these uses without major modification. Also included are areas likely to undergo frequent changes of use or where the future use in unknown. Chemical packaging facilities, hospital facilities, pan washing apparatus, fertiliser injection systems, chemical dispensers (high toxicity), food preparation fixtures with clean in place systems, industrial shed complexes and light commercial properties. Wash down of spills puts chemicals packaging / storage into this category even if liquid batching and storage is not practised. Also applies where there is no certainty about the type of activities to be practiced and the materials used. 3
Table B5V1d Cross-connection type
Site condition Common examples Notes Score
The product or installation presents no possibility of cross-connection to food, drink or water or other liquid vessels other than those used for domestic purposes. Residential units and offices. There are no water storage tanks, swimming pools, spas or commercial kitchens on site or able to be installed. 0
The product or installation presents a potential for a cross-connection between a drinking water service and a commercial food, drink or water or other liquid vessel, or any vessel intended for low hazard chemicals. Small scale food processing facilities. Potential backflow from low volume of non-hazardous substances. Non-hazardous chemicals are any substances not required to display a hazardous substance label. 1
The product or installation presents a potential for a cross-connection between a drinking water service and a non-drinking water service. Drinking water outlets within close proximity to an alternative water source such as a Network Utility Operator drinking water supply, bore or irrigation system. Potential connection of a drinking water system and a system identified with a Low Hazard. 2
The product or installation presents a potential for cross-connection between the drinking water service and a swimming pool, water storage tank used for commercial purposes, large scale food and drink processing operations, a vessel, pipe or body of liquid containing a hazardous substance or Schedule 5 poison, recycled water service with biological matter or faecal contamination. Building header tanks, commercial swimming pool make up water connections, soft drink manufacturers. Potential connection of a drinking water system and a system containing an hazardous substance or low toxicity poison or large quantities of food or drink product. Hazardous chemicals are any substances required to display a hazardous substance label. 3
The product or installation presents the potential for cross-connection between the drinking water service and a bulk water service vessel containing a hazardous substance or Schedule 5 poison. Chemical make-up water connected to a chemical batching process. Any potential connection to a system containing large volumes of hazardous material or moderately poisonous material. 4
The product or installation has potential for a cross-connection to a sewerage source, a trade waste source, a vessel with human or animal biological or faecal matter, a vessel pipe or body of liquid containing any quantity of a Schedule 1 to 4 or Schedule 6 to 8 poison. Recycled water irrigation system with drinking water back up supply. Applies to potential connections with a high health risk. 5
Table B5V1e Extent of contamination
Site condition Common examples Notes Score
The product or installation presents a cross-connection that will only affect 1 small property (fewer than 10 people). Domestic residences Small site where a cross-connection will affect the drinking water to fewer than 10 people. 1
The product or installation presents a cross-connection that will affect a moderate size property or multiple small sites within the same property (fewer than 100 people). Cafes or small restaurants on a single title property. Cross-connection will potentially affect drinking water to fewer than 100 people. 2
The product or installation presents a cross-connection that will affect a large property or could allow contaminants to enter other properties. Tenancies within a shopping complex, connected via water meters without Containment protection. Cross-connection will affect drinking water to 100 people or greater. Consideration is needed as to whether water meters may not have suitable backflow protection or may not be adequate to mitigate the risk. 3

Deemed-to-Satisfy Provisions

(1) Where a Deemed-to-Satisfy Solution is proposed, Performance Requirement B5P1 is satisfied by complying with B5D2 to B5D6.

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

(1) A hazard exists wherever it is possible for water or contaminants to enter a drinking water service or supply via any potential cross-connection between—

  1. the drinking water service; and
  2. any of the following:
    1. A non-drinking water service.
    2. A rainwater service.
    3. An alternative water supply.
    4. A swimming pool.
    5. Pipes, fixtures or specialist equipment (including boilers and pumps) containing chemicals, liquids, gases or other substances which may be harmful to health or safety.

(2) Each hazard must—

  1. be assigned an Individual protection Hazard Rating or Zone protection Hazard Rating in accordance with S41C4 and S41C5 ; and
  2. be isolated from the drinking water service by an appropriate backflow prevention device which is selected and installed in accordance with Section 4 of AS/NZS 3500.1.

(3) Where a site is served by a Network Utility Operator’s drinking water supply, appropriate containment protection must be selected and installed in accordance with Section 4 of AS/NZS 3500.1.

(1) A hazard exists wherever it is possible for water or contaminants to enter a non-drinking water service or supply via any potential cross-connection between itself and another separate non-drinking water service on the same site.

(2) Each hazard must—

  1. be assigned a Containment protection Hazard Rating in accordance with S41C6; and
  2. be isolated from the non-drinking water service by appropriate containment protection which is selected and installed in accordance with Section 4 of AS/NZS 3500.1.

Explanatory information

A ‘separate non-drinking water service’ means one which draws water from a different source. For example, on a site connected to both recycled water and bore water, both may be considered non-drinking water services, but are drawn from different sources. Therefore, each would be a ‘separate non-drinking water service’.

Each fire-fighting water service must—

  1. be assigned a Hazard Rating in accordance with S41C7; and
  2. be isolated from the drinking water service by an appropriate backflow prevention device which is selected and installed in accordance with Section 4 of AS/NZS 3500.1.

Water downstream of a backflow prevention device protected by individual protection or zone protection is considered to be an unprotected water service.

NCC Blurbs

Protection of drinking water services from rainwater must be in accordance with AS/NZS 3500.1(2018) Clause 16.4 and Table 16.4 with the additions;

  1. After 16.4, insert clause 16.4.1 as follows: 16.4.1 A reduction of the Hazard Rating listed in table 16.4 may be permitted following a risk assessment of the design and installation of the rainwater tank and other environmental factors in accordance with clause 16.4.2.
  2. After 16.4.1, insert clause 16.4.2 as follows: 16.4.2 For buried rainwater tanks and partially buried rainwater tanks without connection to a drinking water supply or with direct or indirect connections to a drinking water supply, a dual-check valve may be used in lieu of a testable device for Containment protection and Zone protection where it has been determined by risk assessment that—
    1. the risk to tank rainwater quality from air pollution is low; and
    2. the risk to tank rainwater quality from groundwater and/or surface water contamination is low. In assessing this risk the permeability of the tank and piping materials and joints to groundwater contaminants should be addressed; and
    3. precautions in the design and installation of the rainwater collection system have been taken to reduce impacts to tank rainwater quality from the roof collection and delivery system. Such measures include, but are not restricted to, appropriate materials, gutter guards, filters, first flush devices, dry inlets, guards to exclude vermin and mosquitoes, and the quality of tank maintenance programs; and
    4. precautions in the design and installation of the rainwater tank have been taken to reduce impacts to tank rainwater quality from groundwater and surface water pollution. Such measures include, but are not limited to—
      1. location and topography; and
      2. structural integrity of the tank including installation factors such as bedding, embedment, compaction and geotechnical specifications; and
      3. water tightness of tank including all penetrations, connections, access covers and joints; and
      4. ingress of vermin through the overflow e.g. by provision of a reflux valve, self-sealing valve, trap check valve; and
      5. the risk assessment results must be submitted to the authority having jurisdiction.
NCC Title

Rainwater

NCC State
SA
NCC Variation Type
Replacement
NCC SPTC Current
Rainwater
NCC Blurbs

Drinking water and non-drinking water must:

  1. be zone protected from above ground, buried or partially buried rainwater tank in Class 1 buildings, utilising a non-testable device; or
  2. comply with AS/NZS 3500.1 (2018) Clause 16.4 and Table 16.4 for all other building classes.

Applications

B5D6 applies to scenarios not covered by S41C6(1)(b).

NCC Title

Rainwater

NCC State
NSW
NCC Variation Type
Replacement
NCC SPTC Current
Rainwater

Protection of drinking water services from rainwater must be in accordance with AS/NZS 3500.1 (2018) Clause 16.4 and Table 16.4.

Applications

B5D6 applies to scenarios not covered by S41C6(1)(b).

NCC Blurbs

Water systems permanently attached to cooling towers backflow prevention shall be positioned so that—

  1. cooling tower air gap must be measured from the rim of the cooling tower basin; and
  2. if a drinking water service to the cooling tower passes through the basin, the service pipe must be provided with a double wall protection; and
  3. if a fast fill connection is required, the fast fill line shall terminate externally to the unit, with an air gap over either the basin or a tundish.

Notes

See NSW Figure B5D7 for typical cooling tower connections.

Insert NSW figure (B5D7) as follows:
NSW Figure B5D7: Typical cooling tower service
image-B5D7-typical-cooling-tower-service-NSW.svg
Figure Notes

Note 1.

Refer to AS/NZS 3500.1 Part 1 Table 4.6.3.2

NCC Title

Cooling tower water service

NCC State
NSW
NCC Variation Type
Insertion
NCC SPTC Current
Cooling tower water service