NCC 2022 Volume Three - Plumbing Code of Australia
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C2

Part C2 Sanitary drainage systems

Part C2 Sanitary drainage systems

Introduction to this Part

This Part sets out the requirements for any part of a sanitary drainage system of a property including from sanitary fixtures, appliances and sanitary plumbing systems from the point of connection to an approved disposal 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 drainage installation; and
  2. ensure that a sanitary drainage installation is suitable; and
  3. conserve water and energy; and
  4. safeguard the environment; and
  5. safeguard public and private infrastructure; and
  6. safeguard people from illness caused by the discharge of swimming pool waste water; and
  7. protect other property from damage caused by the discharge of swimming pool waste water; and
  8. ensure that a sanitary drainage installation is designed and is capable of being maintained so that throughout its serviceable life it will continue to satisfy Objectives (a) to (g).

Functional Statements

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

Adequate means for the disposal of swimming pool water and drainage is to be provided for each swimming pool.

Performance Requirements

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

NCC Title

Swimming pool drainage

NCC State
NT
NCC Variation Type
Deletion
NCC SPTC Current
Swimming pool drainage

A swimming pool must have adequate means of draining the pool in a manner that will not—

  1. cause illness to people; or
  2. affect other property.

A sanitary drainage system must ensure there is access for maintenance and clearing a blockage.

(1) A sanitary drainage system must ensure there is adequate ventilation to avoid foul air and gases accumulating in the sanitary drainage and sewerage system.

(2) A sanitary drainage 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).

(1) A sanitary drainage system must ensure protection against internal contamination.

(2) A sanitary drainage system must avoid the entry of water, foul air and gases from the system into buildings.

(3) A sanitary drainage system must avoid the entry of surface water, sub-surface water and stormwater into the system.

A sanitary drainage system must avoid blockage and uncontrolled discharge.

(1) A sanitary drainage system must avoid damage from root penetration, superimposed loads or ground movement.

(2) A sanitary drainage system must avoid damage to existing buildings or siteworks.

(3) A sanitary drainage system must avoid damage to the Network Utility Operator's sewerage system or other approved disposal system.

Notes

There are no Deemed-to-Satisfy Provisions for sanitary drainage systems to address ground movement.

NCC Blurbs

Where a point of connection to a Network Utility Operator's sewerage system is not available, an on-site wastewater management system must be designed, installed and maintained in accordance with the requirements and agreement of the relevant authority having jurisdiction.

NCC Title

No point of connection

NCC State
VIC
NCC Variation Type
Insertion
NCC SPTC Current
No point of connection

Verification Methods

Compliance with C2P1 is achieved if the sanitary drainage system is designed to operate with—

  1. a liquid-to-air ratio of between 1 to 1 and 0.65 to 0.35; and
  2. a minimum velocity of 0.8 m/s; and
  3. a maximum velocity of—
    1. 2 m/s under normal operating conditions; and
    2. 3.5 m/s under surge conditions.

Explanatory information

  • The purpose of the minimum velocity is to minimise the likelihood of blockage in the sanitary drainage system.
  • The maximum velocity is intended to minimise the likelihood of damage to the system.
NCC Title

Pressure testing

NCC State
VIC
NCC Variation Type
Deletion
NCC SPTC Current
Pressure testing

Compliance with C2P1 is achieved if the sanitary drainage system passes one or more of the pressure tests set out in Section 15 of AS/NZS 3500.2.

(1) Compliance with C2P1 for pipe sizing is verified for each sanitary drainage pipework section when the design flow rate is not less than—

  1. the probable simultaneous wastewater flow rate calculated in accordance with (2); or
  2. the Discharge Unit (DU) value of the highest fixture connected upstream of the pipework section as given by Table C2V3b, in litres per second, whichever is greater.

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

QTotal=K∑DU+QOtherMathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyuaSGaam ivaiaad+gacaWG0bGaamyyaiaadYgakiabg2da9iaadUeadaGcaaqa amaaqaeabaGaamiraiaadwfaaSqabeqaniabggHiLdaaleqaaOGaey 4kaSIaamyuaSGaam4taiaadshacaWGObGaamyzaiaadkhaaaa@478C@  

(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).
  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).
  3. KMathType@MTEF@5@5@+= feaahqart1ev3aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4saaaa@36C4@
    = the frequency factor given in Table C2V3a (dimensionless).
  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 C2V3b connected upstream of that pipework section (dimensionless).

Explanatory information

System types referred to in Table C2V3b are as follows:

  • System 1 - A sanitary drainage system where branch discharge pipes are designed with a filling degree of 50%.
  • System 2 - A sanitary drainage system where branch discharge pipes are designed with a filling degree of 70%.
  • System 3 - A sanitary drainage system where branch discharge pipes are designed with a filling 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, as 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.
Table C2V3a Frequency factors
Fixture usage NCC building class 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 the general public, school Class 9b 1.0
Special use e.g. laboratory Not applicable 1.2
Table C2V3b Discharge units
Fixture System 1 - Discharge Units (DU) System 2 - Discharge Units (DU) System 3 - Discharge Units (DU)
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

Deemed-to-Satisfy Provisions

(1) Where a Deemed-to-Satisfy Solution is proposed, Performance Requirements C2P1 to C2P7 are satisfied by complying with C2D2 to C2D5.

(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.

Pumped discharge from a swimming pool must connect to the sanitary drainage system in accordance with AS/NZS 3500.2.

NCC Blurbs

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

  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
NCC Blurbs

(1) A sanitary drainage system must be in accordance with AS/NZS 3500.2; subject to the following—

  1. insert Clause 4.4.2.1(e): (e) Where an inspection shaft or boundary trap riser in a below ground sanitary drainage system is located clear of a building and is not likely to be damaged by vehicular traffic, a light cover must be installed in accordance with clause 4.4.2.1(a) and clause 4.4.2.1(c)(ii) and (iii).
  2. insert Clause 4.6.2(d): (d) Have risers installed vertically with no offsets.
  3. clause 5.3(c) of AS/NZS 3500.2 is varied so that concrete support used to support drains must be provided to support all bends greater than DN 65 to vertical risers.
  4. replace Clause 5.4.2(d) with: Free running sand, excavated from the trench, capable of passing through a 2 mm mesh sieve, which does not contain clay, organic or other deleterious materials.
  5. Insert Clause 15.1(b) as follows: Testing of a sanitary drainage installation. If installed at a property provided with non-drinking water by the Network Utility Operator, testing of a sanitary drainage installation may be carried out in accordance with—
    1. a water test using non-drinking water provided by the Network Utility Operator in accordance with clause 15.2; or
    2. an air test in accordance with clause 15.3; or
    3. vacuum test in accordance with clause 15.4; or
    4. in cases other than in (a), testing may be carried out by way of—
      1. an air test in accordance with clause 15.3; or
      2. a vacuum test in accordance with clause 15.4.

(2) Discharge pipes measuring DN 50 or smaller must not be installed in a below ground sanitary drainage system, except for discharge pipes connected to floor waste gullies or vertical riser from a graded drain.

NCC Title

General requirements

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

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

  1. For clause 4.3.1 insert (i) as follows: Must not have DN40 or DN50 traps installed.
  2. For clause 4.4.1 insert the following as the second paragraph: Boundary trap or inspection shafts cannot terminate within areas of buildings as defined in the NCC as a habitable room. See NCC “Definitions” and delete ‘but’ from (a) and replace with ‘,” and delete ‘excludes’ from (b).
  3. After clause 4.5.2(b) insert (c) as follows: Soil and waste stacks shall not discharge through a reflux valve except where a reflux valve is installed at the connection to the sewer required with surcharging sewers.
  4. Substitute clause 4.5.3 as follows: Where a surcharge is likely to occur and a reflux valve is to be installed, it shall be located in accordance with (i) and (ii) as follows:
    1. Where the drain has an inspection shaft or boundary trap, the reflux valve shall be located immediately downstream from and adjacent to the outlet of the shaft or trap.
    2. The invert of the outlet of the reflux valve shall be installed a minimum of 80 mm higher than the invert of the Network Utility Operator’s system it is connected to. See NSW Figures C2D4a and C2D4b.
  5. After clause 4.7.1(h) insert (i) as follows: At each branch off a main line internal of the building connecting one or more water closets or slop hoppers. In these cases. inspection openings must be raised to finished surface level in an accessible position and sealed with an airtight cover. If access to the under floor area is more than 600 mm above the inspection opening, the riser may be omitted.
  6. After clause 12.7(g) insert (h) as follows: Sewage management facilities shall be accredited by NSW Health and comply with local government requirements. Before a connection is made to pump raw sewage or effluent from a septic tank or holding well to the Network Utility Operator’s sewer, an application must be made to that Network Utility Operator. Applicants must meet the pump to sewer requirements and conditions for all connections to the sewer. A marker tape must be laid along the top of all pump discharge or rising mains pipes at intervals of not more than 3 m.
Insert NSW figure (C2D4a) as follows:
NSW Figure C2D4a: Reflux valves - diagram 1
image-C2D4a-reflux-valves-diagram-1-NSW.svg
Insert NSW figure (C2D4b) as follows:
NSW Figure C2D4b: Reflux valves - diagram 2
image-C2D4b-reflux-valves-diagram-2-NSW.svg

Notes

Where a reflux valve is installed the valve remains the responsibility of the property owner.

NCC Title

General requirements

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

(1) A sanitary drainage system must be in accordance with AS/NZS 3500.2.

TAS C2D4 General requirements2019: C2.4

Insert TAS subclause C2D4(2) in clause C2D4 as follows:

(2) For Tasmanian venting requirements see TAS C2D6.

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

NCC Blurbs

(1) A sanitary drainage system must provide ventilation in accordance with AS/NZS 3500.2.

(2) A sanitary drainage system which connects to an on-site wastewater management system must have—

  1. a secondary vent within 10 metres of the on-site wastewater management system; or
  2. where (a) cannot be achieved, a low level (ground) vent at the sanitary drainage point of connection.

(3) A sanitary drainage system which connects to an on-site wastewater management system must have inspection openings that—

  1. are located at the point of connection to an on-site wastewater management system; and
  2. terminate at or above finished surface level.

Explanatory information

See TAS Figure C2D6 Alternative venting arrangements

Insert TAS figure (C2D6 (explanatory)) as follows:
TAS Figure C2D6 (explanatory): Venting requirements
image-C2D6-venting-requirements-TAS.svg
NCC Title

Venting requirements

NCC State
TAS
NCC SPTC Current
Venting requirements

Explanatory information: Cross-volume considerations

NCC Volumes One and Two deal with a number of areas of on-site construction which are relevant to a sanitary drainage system. These include, but are not limited to, those listed in Table C2.

Table C2 Cross-volume considerations
Item NCC Volume One Class 2 to 9 buildings NCC Volume Two Class 1 and 10 buildings
Excavations for pipework adjacent to a building and footings B1 Structural provisions H1 Structure
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