Part C1 Sanitary plumbing systems

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).

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.

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

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).

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.

(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:

(3) In the equation shown at (2)—

1. $QTotal$

   = the probable simultaneous wastewater flowrate for that pipework section (l/s); and

2. $QOther$

   = the sum of any other wastewater flowrates such as pumped discharges (l/s); and

3. $K$

   = the frequency factor given in Table C1V1a (dimensionless); and

4. ${\displaystyle \sum DU}$

   = the sum of the discharge units as given in Table C1V1b, connected upstream of that pipework section (dimensionless).

(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.

(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.

(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.

(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.

(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.

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).