NCC 2022 Volume Three - Plumbing Code of Australia
Classification
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C1

Part C1 Sanitary plumbing systems

Part C1 Sanitary plumbing systems

Introduction to this Part

This Part sets out the requirements for any part of a sanitary plumbing system of a property including from sanitary fixtures and appliances from the point of connection to a sanitary drainage system.

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 sanitary plumbing installation; and
  2. ensure that a sanitary plumbing 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 sanitary plumbing installation is designed and is capable of being maintained so that throughout its serviceable life it will continue to satisfy Objectives (a) to (e).

Functional Statements

Sanitary fixtures and sanitary appliances must be provided with an adequate disposal system that does not impact adversely on the occupants of the premises, property, the environment or the Network Utility Operator’s infrastructure.

Performance Requirements

A sanitary plumbing system must ensure sewage or sullage is transferred to a sanitary drainage system or an approved disposal system.

Explanatory information: Non-flushing (waterless) urinals

Where a non-flushing (waterless) urinal is to be installed to a sanitary plumbing system comprising copper, copper alloy or other metallic piping, undiluted discharge transported through such pipework may increase the likelihood of corrosion.

Practitioners should also be aware that undiluted discharge, transported through pipework of any material, can cause a build-up of struvite (ammonium magnesium phosphate) inside the pipework, potentially causing blockage within the sanitary plumbing system.

A sanitary plumbing system must ensure access for maintenance of mechanical components, operational controls and for clearing blockages.

A sanitary plumbing system must ensure efficient use of drinking 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; or
  2. water saving measures equivalent to or greater than those described in (a).

Applications

The flush volume of C1P3 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 C1P3 do not apply to a vacuum drainage system.

A sanitary plumbing system must avoid blockage or uncontrolled discharge.

A sanitary plumbing system must ensure that ventilation is provided to avoid hydraulic load imbalance such that—

  1. there is less than a 1% likelihood during the annual peak hour that when any fixture discharges, air pressure at any trap seal exceeds ±375 Pa difference from atmospheric pressure; or
  2. an equivalent level of safety to human health is achieved as a system complying to (a).

Exemptions

C1P5 Ventilation does not apply to vacuum drainage systems.

A sanitary plumbing system must avoid—

  1. entry of water, sewerage and sullage from the system into buildings; and
  2. entry of foul gases from the system into buildings, such that—
    1. at pressures of up to ±375 Pa, water trap seals will not be reduced to depths less than 70 mm for trap seals in pressurised rooms and 25 mm for all other applications; or
    2. an equivalent level of safety to human health is achieved as a system complying to (i); and
  3. entry of surface water, subsurface water and stormwater into the system.

A sanitary plumbing system must avoid damage from superimposed loads, ground movement or root penetration.

Verification Methods

(1) Compliance with C1P3 for pipe sizing is verified for each sanitary plumbing pipework section when the discharge flowrate is not less than the greater of—

  1. the probable simultaneous wastewater flowrate calculated in accordance with (2); or
  2. the Discharge Unit (DU) value of the highest fixture connected upstream of the pipework section as given in Table C1V1b, in litres per second.

(2) For the purposes of (1)(a), for each pipework section, the design probable simultaneous wastewater flowrate must be calculated in accordance with the following:

QTotal=K∑DU+QOther​MathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyuaSGaam ivaiaad+gacaWG0bGaamyyaiaadYgakiabg2da9iaadUeadaGcaaqa amaaqaeabaGaamiraiaadwfaaSqabeqaniabggHiLdaaleqaaOGaey 4kaSIaamyuaSGaam4taiaadshacaWGObGaamyzaiaadkhakiaaygW7 aaa@4920@  

(3) In the equation shown at (2)—

  1. QTotalMathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyuaSGaam ivaiaad+gacaWG0bGaamyyaiaadYgaaaa@3B72@
    = the probable simultaneous wastewater flowrate for that pipework section (l/s); and
  2. QOtherMathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyuaSGaam 4taiaadshacaWGObGaamyzaiaadkhaaaa@3B70@
    = the sum of any other wastewater flowrates such as pumped discharges (l/s); and
  3. KMathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4saaaa@36C4@
    = the frequency factor given in Table C1V1a (dimensionless); and
  4. ∑DUMathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaabqaeaaca WGebGaamyvaaWcbeqab0GaeyyeIuoaaaa@39AB@
    = the sum of the discharge units as given in Table C1V1b, connected upstream of that pipework section (dimensionless).
Table C1V1a Frequency factors
Fixture usage NCC building classes Frequency factor (K)
Intermittent use e.g. dwelling, guesthouse or office Class 1, Class 2, Class 3 or Class 4 0.5
Frequent use e.g. hospital, restaurant or hotel Class 5, Class 6, Class 7, Class 8, Class 9a or Class 9c 0.7
Congested use e.g. open to general public, school Class 9b 1.0
Special use e.g. laboratory Not applicable 1.2
Table C1V1b Discharge units
Fixture System 1 System 2 System 3
Basin 0.5 0.3 0.3
Shower 0.6 0.4 0.4
Urinal 0.8 0.5 0.4
Bath 0.8 0.6 1.3
Kitchen sink 0.8 0.6 1.3
Water closet 2.0 1.8 1.2
Washing machine - up to 6 kg 0.8 0.6 0.6
Domestic dishwasher 0.8 0.6 0.2

Explanatory information

System types referred to in Table C1V1b are as follows:

  • System 1 - A sanitary plumbing system where branch discharge pipes are designed with a filling degree of 50%.
  • System 2 - A sanitary plumbing system where branch discharge pipes are designed with a filling degree of 70%.
  • System 3 - A sanitary plumbing system where branch discharge pipes are designed with a filing degree of 100%.
  • Systems 1 and 2 are similar to the fully vented modified system and System 3 is similar to the single stack system detailed in AS/NZS 3500.2.
  • Filling degree is defined as the ratio between the height of fluid in a pipe (h) and the diameter of the pipe (D), or h/D.

(1) Compliance with C1P5 for pipe sizing is verified for each common discharge branch when—

  1. pipework is in accordance with (2); and
  2. ventilation is in accordance with (3).

(2) Each unvented common discharge pipe within the system must have—

  1. a pipe length from trap weir to stack less than 4 m; and
  2. no more than three 90º bends, excluding the first bend after the trap outlet; and
  3. no vertical drops of greater than 45º inclination between the trap weir and the stack greater than 1 m; and
  4. a gradient greater than 1.00%; and
  5. a pipe size in accordance with Table C1V2.

(3) Each vented common discharge pipe within the system must have—

  1. a pipe length from trap weir to the stack of less than 10 m; and
  2. no vertical drops of greater than 45º inclination, between the trap weir and the stack greater than 3 m; and
  3. a gradient greater than 0.50%; and
  4. a pipe size in accordance with Table C1V2; and
  5. a group vent sized in accordance with Table C1V2; and
  6. each group vent either—
    1. terminates to atmosphere or interconnects with another vent in accordance with AS/NZS 3500.2; or
    2. terminates at an air admittance valve with a minimum airflow rate equal to the wastewater design flowrate.

Limitations

Water closets must only be connected to a DN 80 or DN 100 discharge pipe.

Table C1V2 Common discharge pipe capacity
Common discharge pipe size - Nominal diameter (DN) Unvented capacity QTotal - Litres per second (l/s) Vented capacity QTotal - Litres per second (l/s) Group vent - Nominal diameter (DN)
40 0.50 N/A N/A
50 0.80 0.75 40
65 1.00 1.50 40
80 2.00 3.00 50
100 2.50 3.75 65

(1) Compliance with C1P5 relating to pipe sizing is verified for each common discharge branch when—

  1. pipework is in accordance with (2); and
  2. ventilation is provided in accordance with (3).

(2) Each unvented common discharge pipe within the system must have—

  1. a pipe length from trap weir to stack less than 10 m; and
  2. no more than one 90º bend, excluding the first bend after the trap outlet; and
  3. no vertical drops of greater than 45º inclination between the trap weir and the stack, greater than—
    1. 1 m, where a water closet is connected to the branch; or
    2. 3 m, where no water closets are connected to the branch; and
  4. a gradient greater than 1.50%; and
  5. a pipe size in accordance with Table C1V3.

(3) Each vented common discharge pipe within the system has—

  1. no vertical drops of greater than 45º inclination between the trap weir and the stack greater than 3 m; and
  2. a gradient greater than 1.50%; and
  3. a pipe size in accordance with Table C1V3; and
  4. a group vent sized in accordance with Table C1V3; and
  5. each group vent either—
    1. terminates to atmosphere or interconnects with another vent in accordance with AS/NZS 3500.2; or
    2. terminates to an air admittance valve with a minimum airflow rate equal to 2 times the wastewater design flowrate.

Limitations

  1. Water closets must only be connected to a DN 80 or DN 100 discharge pipe.
  2. No more than one water closet can be connected to a DN 80 discharge pipe.
Table C1V3 System 2 - Common discharge pipe capacity
Common discharge pipe - Nominal diameter (DN) Unvented capacity QTotal - Litres per second (l/s) Vented capacity QTotal - Litres per second (l/s) Group vent - Nominal diameter (DN)
40 0.50 0.75 32
50 1.00 1.50 32
65 1.50 2.25 40
80 2.25 3.40 40
100 2.50 3.75 50

(1) Compliance with C1P5 relating to pipe sizing is verified for each discharge branch when—

  1. each unvented fixture, or combination of fixtures, connects independently to the stack in accordance with Table C1V4a; and
  2. each vented fixture, or combination of fixtures, connects to the stack in accordance with Table C1V4b.

(2) Ventilation requirements must be in accordance with the following:

  1. Each trap vent must be—
    1. not less than DN 50, where the connection of the vent to the branch is liable to blockage due to splashing or submergence; or
    2. DN 32, where the connection of the vent to the branch is not liable to blockage due to splashing or submergence.
  2. Each trap vent connects within 750 mm of the fixture it serves.
  3. Each trap vent must—
    1. terminate at atmosphere or interconnect with another vent in accordance with AS/NZS 3500.2; or
    2. connect to a common trap vent at least 40 mm in diameter; or
    3. connect to the stack above the flood level of the highest fixture; or
    4. terminate to an air admittance valve with a minimum airflow rate equal to 2 times the wastewater design flowrate.

(3) Each branch connection must use a sweep or 45° junction where the branch is—

  1. an equal diameter to the stack; and
  2. the stack is DN 80 or larger.
Table C1V4a System 3 - Unvented fixture connections
Fixture Waste Nominal Diameter (DN) Maximum length, in metres (m) Minimum gradient (%) Maximum gradient (%) Maximum number of bends Maximum vertical drop, in metres (m)
Basin 32 1.7 2.2 2.2 0 0
Basin 32 1.1 4.4 4.4 0 0
Basin 32 0.7 8.7 8.7 0 0
Basin 40 3 1.8 4.4 2 0
Basin group ≤4 basins 50 4 1.8 4.4 0 0
Bidet 32 1.7 2.2 2.2 0 0
Bidet 32 1.1 4.4 4.4 0 0
Bidet 32 0.7 8.7 8.7 0 0
Bidet 40 3 1.8 4.4 2 0
Shower 40 No limit 1.8 9 No limit 1.5
Bath 40 No limit 1.8 9 No limit 1.5
Single urinal 40 3 1.8 9 No limit 1.5
Slab urinal 65 3 1.8 9 No limit 1.5
Sink - kitchen 40 No limit 1.8 9 No limit 1.5
Trough - laundry 40 3 1.8 9 No limit 1.5
Domestic dishwasher 40 3 1.8 4.4 No limit 1.5
Domestic clothes washing machine - up to 6 kg 40 3 1.8 4.4 No limit 1.5
Water closet 80 No limit 1.8 No limit No limit 1.5
Water closet 100 No limit 1.8 No limit No limit 1.5
Water closet group ≤8 water closets 100 15 0.9 9 2 1.5
Food waste disposal unit 40 3 13.5 No limit No limit 1.5
Sanitary napkin disposal unit 40 3 5.4 No limit No limit 1.5
Floor waste gully 50 No limit 1.8 No limit No limit 1.5
Floor waste gully 80 No limit 1.8 No limit No limit 1.5
Floor waste gully 100 No limit 1.8 No limit No limit 1.5
Table C1V4b System 3 - Vented fixture connections
Fixture Waste Nominal Diameter (DN) Maximum length, in metres (m) Minimum gradient (%) Maximum gradient (%) Maximum number of bends Maximum vertical drop, in metres (m)
Basin 32 3 1.8 No limit 2 3
Basin 40 3 1.8 No limit No limit 3
Basin group ≤5 basins 50 7 1.8 4.4 No limit No limit
Basin group ≤10 basins 50 10 1.8 4.4 No limit No limit
Bidet 32 3 1.8 No limit 2 3
Bidet 40 3 1.8 No limit No limit 3
Shower 40 No limit 1.8 No limit No limit No limit
Bath 40 No limit 1.8 No limit No limit No limit
Single urinal 40 3 1.8 No limit No limit 3
>1 Single urinal 50 No limit 1.8 No limit No limit No limit
Trough urinal 50 3 1.8 No limit No limit 3
Slab urinal 65 3 1.8 No limit No limit 3
Sink - kitchen 40 No limit 1.8 No limit No limit No limit
Trough - laundry 40 3 1.8 No limit No limit No limit
Domestic dishwasher 40 No limit 1.8 No limit No limit No limit
Domestic clothes washing machine (up to 6 kg) 40 No limit 1.8 No limit No limit No limit
Water closet 80 No limit 1.8 No limit No limit No limit
Water closet 100 No limit 1.8 No limit No limit No limit
Water closet group ≤8 100 15 0.9 No limit No limit No limit
Food waste disposal unit 40 3 13.5 No limit No limit 3
Sanitary napkin disposal unit 40 3 5.4 No limit No limit 3
Floor waste gully 50 No limit 1.8 No limit No limit No limit
Floor waste gully 80 No limit 1.8 No limit No limit No limit
Floor waste gully 100 No limit 1.8 No limit No limit No limit
Small potato peeler 40 3 13.5 No limit No limit 3

Limitations

  1. The maximum number of bends permitted is measured from the fixture trap weir to the connection to the stack, excluding the first bend after the trap weir.
  2. The maximum pipe length is measured from the fixture trap weir to the connection to the stack. 
  3. A slab urinal must not cater for more than 7 people. Additional waste outlets may be required for longer urinals.
  4. Where a water closet is connected, sweep or 45º junctions must be used to connect to the stack.
  5. Bottle and resealing traps are not permitted for food waste disposal units or sanitary napkin disposal units.

(1) Compliance with C1P5 relating to pipe sizing is verified for the stack system when—

  1. each stack has a pipe size in accordance with (2); and
  2. ventilation is provided in accordance with (3).

(2) Each stack must have a pipe size in accordance with—

  1. Table C1V5a, where a separate relief vent is not provided; or
  2. Table C1V5b, where a separate relief vent is provided.

(3) Ventilation must comply with the following:

  1. Each stack vent must terminate either to—
    1. the atmosphere or interconnect with another vent in accordance with AS/NZS 3500.2; or
    2. an air admittance valve with a minimum airflow rate equal to 8 times the wastewater design flowrate.
  2. Each stack vent must be sized in accordance with—
    1. Clause 8.5.4 of AS/NZS 3500.2 for stack vents; or
    2. Clause 8.5.3 of AS/NZS 3500.2 for relief vents.
  3. Each relief vent must interconnect with the stack vent at each floor.

Applications

  1. Water closets must be connected to a DN 80 or DN 100 discharge pipe.
  2. Water closets must not be connected to DN 80 where a C1V2 System 1 or C1V4 System 3 is used.
Table C1V5a Stack capacity without a relief vent
Stack Nominal Diameter (DN) Capacity with square or 88° junction, in litres per second (l/s) Capacity with sweep or 45° junction, in litres per second (l/s)
65 0.5 0.7
80 2.0 2.5
100 4.0 5.2
150 9.5 12.4
Table C1V5b Stack capacity with a relief vent
Stack Nominal Diameter (DN) Capacity with square or 88° junction, in litres per second (l/s) Capacity with sweep or 45° junction, in litres per second (l/s)
65 0.7 0.9
80 2.6 3.4
100 5.6 7.3
150 12.4 18.3

Deemed-to-Satisfy Provisions

(1) Where a Deemed-to-Satisfy Solution is proposed, Performance Requirement C1P1 to C1P7 is satisfied by complying with C1D2 and C1D5.

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

The invert level of a trap or gully weir must be a minimum of 10 mm higher than the soffit of the pipe to which it connects.

NCC Blurbs

A sanitary plumbing system must be in accordance with AS/NZS 3500.2 subject to the following:

  1. For Class 1 buildings, substitute Clause 6.6.2.4.2 as follows:
    1. 6.6.2.4.2 New installations: Where a junction is used to make the connection of a DN 100 branch pipe to another DN 100 pipe, the entry level of the branch pipe shall be elevated at an incline of not less than 15° above the horizontal. Where the 15° requirement cannot be achieved, the incline must be as close as possible to 15° to avoid stranding. Where a fixture is connected to a graded discharge pipe, the installation shall also be in accordance with Clause 6.6.2.1.
  2. After clause 13.9(b), delete the following: Where a bath trap is not accessible, the bath shall discharge untrapped to a floor waste gully (FWG) in accordance with Table 4.6.7.2 and Appendix B.
  3. After clause 15.1, insert clause 15.1A as follows: When tested, the respective sections of any soil pipe, waste pipe, vent pipe or above-ground drain must be free of leaks when subjected to an air test in accordance with clause 15.3.
  4. Substitute clause 15.3.3 as follows: When tested, the respective sections of any soil pipe, waste pipe, vent pipe or above ground drain must be free of leaks when subjected to an air test in accordance with clause 15.3.2 over the minimum test duration specified in Table 15.3.2.
NCC Title

General requirements

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

A sanitary plumbing system must be in accordance with AS/NZS 3500.2 with the following variations:

  1. After AS/NZS 3500.2 clause 3.9.1 (g) insert (h) and (i) as follows: (h) at the downstream end of a trade waste arrestor close to the outlet; and (i) at the upstream end of a trade waste drain connected to a trade waste arrestor and fitted with a wind driven turbine ventilator at the termination.
  2. After AS/NZS 3500.2 clause 3.9.3.1 (e) add (f) and (g) as follows: (f) where required by Clause 3.9.1 (h) the downstream vent on any trade waste drain shall not be less than DN80; and (g) where required by Clause 3.9.1 (g) the upstream vent on a trade waste drain shall not be less than DN80.
  1. After AS/NZS 3500.2 clause 4.7.1(h), insert clause 4.7.1(i) as follows: Inspection openings indicated in 4.7.1(b), (d) (e) and (f) shall be raised to finished surface level. All other inspection openings need not be raised provided they are not below paved, concreted or similar finished surfaces.
  2. Substitute AS/NZS 3500.2 clause 2.3(a) as follows: Bends in pipes shall have a throat radius complying with Table 5.6 and Figure B6 of AS/NZS 1260 (2017) and shall be free from wrinkling and flattening.
  3. After AS/NZS 3500.2 clause 12.7(g), insert clause 12.7(h) as follows: Buried pumped discharge pipes and rising mains shall be placed in close-fitting durable sleeving or continually spirally wrapped. The sleeving or spiral wrapping shall be identified for the full length with the following statement: "sewer rising main" or "pumped discharge pipe" in accordance with AS 1345.
  4. After AS/NZS 3500.2 clause 12.7(h), insert clause 12.7(i) as follows: Above ground pumped discharge pipes and rising mains shall be permanently identified with the following statement: "sewer rising main" or "pumped discharge pipe" in accordance with AS 1345. The statement shall be installed in a visible position running longitudinally, at no more than 3 metre intervals.
  5. After AS/NZS 3500.2 clause 13.27.2, insert clause 13.28 as follows: All trade waste pre-treatment equipment shall connect to the sewerage system via a disconnector gully.
NCC Title

General requirements

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

A sanitary plumbing system must be in accordance with AS/NZS 3500.2.

A sanitary plumbing system in a designated bushfire prone area must be in accordance with AS 3959.

A sanitary plumbing system must ensure the efficient use of drinking 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; or
  2. water saving measures equivalent to or greater than those described in (a).

Applications

The flush volumes of C1D5 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 C1D5 do not apply to a vacuum drainage system.

Explanatory information: Cross-volume considerations

NCC Volumes One and Two deal with a number of areas of on-site construction which are relevant to sanitary plumbing services. These include, but are not limited to, those listed in Table C1.

Table C1 Cross-volume considerations
Item NCC Volume One Class 2 to 9 buildings NCC Volume Two Class 1 and 10 buildings
Termite management for attachments to buildings and penetrations through a slab B1 Structural provisions H1 Structure
Penetrations for pipework through a vapour barrier B1 Structural provisions H1 Structure
Pipework in timber bearers and joists of solid timber or engineered wood products B1 Structural provisions H1 Structure
Fittings, fixtures and pipework installations in steel framed construction B1 Structural provisions H1 Structure
Penetrations through a fire-resisting wall or floor C1 Fire resistance Performance Requirements and C4 Protection of openings H3 Fire safety
Fixtures and fittings in a wet area F2 Wet areas and overflow protection  H4 Health and amenity
Service pipework external to the building and penetrations through roof cladding in a bushfire prone area G5 Construction in bushfire prone areas H7 Ancillary provisions and additional construction requirements
Flues, chimneys, pipes, gas storage, domestic fuel tanks, cooling or heating appliances or other services C4 Protection of openings H3 Fire safety
Pipework sound insulation F7 Sound transmission and insulation H4 Health and amenity