G13 Foul Water

Which document covers which part of a building's sanitary plumbing and drains, the ways to comply, which system suits which building, and the sizes to design to.

  • G13/AS1Second Edition Amendment 102 Nov 2023
  • Building Regulations 1992
  • AS/NZS 3500.2:2025
Tools
ToolDrainage design. Put the fixtures on your own plans and get the plumbing and drains sized, vented and drawn.Open →

Who covers what

G13/AS2 · drains below ground, to DN 150G13/AS1Above groundBasement, AS13 levels or lessG13/AS3AS/NZS 3500.2No level limitSewer →
G13/AS1 Sanitary plumbingAS1 1.0.1 to 1.0.3
Gravity pipework above ground, and in a basement, for a building of 3 levels or less. A fully vented system: every discharge pipe is vented except the cases Table 5 lists.
Not for specialised fixtures in hospitals, laboratories or factories, nor wastes that need treating before the sewer.
G13/AS2 DrainageAS2 1.0.1, 1.0.2
Gravity drains below ground of 150 mm or less, sized from G13/AS1's discharge units. No limit on the building's height.
Not for industrial, chemical or toxic wastes, which go to G14/VM1.
G13/AS3, AS/NZS 3500.2AS3 1.0.1, 1.0.2
Plumbing and drainage together, by AS/NZS 3500.2:2021 with Amendment 1 and five changes. No limit on levels, building type or drain size.
Its common effluent drainage and multi-unit development sections are left out.

Ways to comply

An acceptable solution or a verification method, followed, is treated as complying with G13. Anything else is an alternative solution, which the building consent authority has to be shown meets the clause.

PathStatusWhat it takes
G13/AS1 with AS2MBIE, Amendment 10Acceptable solutionA building of 3 levels or less, gravity only, drains to 150 mm. Fixture units from Table 2, pipe sizes and gradients from Table 4 and AS2 Table 2, vents, relief vents, zones, gullies and access points.
G13/AS3AS/NZS 3500.2:2021 + A1Acceptable solutionA design to that edition's rules with G13's five changes applied. Any height.
AS/NZS 3500.2:2025Published 17 April 2025Alternative solutionThe current edition, which G13 does not cite yet. Read as it stands, without G13's changes, for the authority to accept.
G13/VM1BS EN 12056-2:2000Verification methodA calculation of the plumbing inside the building to the European standard. Plumbing only, not drains.
G13/VM2None adoptedNo methodThere is no verification method for drainage; its comment points to G13/AS3.
G13/VM4AS/NZS 1547:2012Verification methodOn-site treatment and disposal where there is no sewer: domestic, up to 14,000 litres a week and 10 people.
Any other designAlternative solutionEvidence that the plumbing and drains meet G13's performance clauses.
G13/AS3's five changes
2.2
Materials meet B2 Durability and the materials paragraphs of G13/AS1 and AS2.
3.19
Common effluent drainage is left out.
4.4
The inspection shaft at the main drain may be any G13 access point.
4.6.6
Overflow relief gullies are asked of Housing only.
Section 14
Multi-unit developments are left out.

Choosing a system

Five ways to vent the plumbing above ground: G13/AS1's own, and the four of AS/NZS 3500.2. The last three rows are our reading of what the clauses above them lead to.

G13/AS1Fully vented, with Table 5's exceptionsFully ventedAS/NZS 3500.2 Section 8Fully vented modifiedAS/NZS 3500.2 Section 8Single stackAS/NZS 3500.2 Section 9Single stack modifiedAS/NZS 3500.2 Section 9
VentsstatedEvery discharge pipe, but the stack's highest connection and the other cases Table 5 listsAS1 1.0.3, Table 5Every trap, but one discharging to a floor waste gully8.2.2 (a)Every branch into the stack; the fixtures grouped on a branch share a group vent8.2.3The stack vent only9.2.1The stack vent, a relief vent and cross-vents9.2.3
A fixture's reachstatedA vented pipe as far as needed; the highest connection unvented to 6 m at DN 100, 1.5 m at DN 80AS1 Table 5Not limited by an unvented length: every trap is vented8.2.2 (a)Own pipe to the branch 2.5 m at most, 6 m at DN 1008.5.7.5.5 (b) to (d)Own pipe to the stack 2.5 m at most, 6 m for a DN 100 WCTable 9.5.1As single stackTable 9.5.1
HeightstatedA building of 3 levels or lessAS1 1.0.1No limit in the stack table, whose last band runs from 4 floor levels upTable 8.2.2(B)As fully vented8.4DN 100 in a home to 10 floor levels; in other buildings, to 4Table 9.7.1DN 100 in a home to 20 floor levels; in other buildings, from 5 to 24Table 9.7.2
DN 100 stackstated195 DU, 65 from one floorAS1 Table 4195 FU to ≤ 3 floor levels, 500 FU from 4Table 8.2.2(B)As fully ventedTable 8.2.2(B)260 FU in a home, 60 FU in other buildingsTable 9.7.1290 to 500 FU in a home, 120 FU in other buildingsTable 9.7.2
FixturesstatedThose Table 2 lists; no specialised fixturesAS1 Table 2, 1.0.2No list limits them, so it takes the fixtures single stack refusesSection 8, Table B.1Any; a basin or bidet trap is DN 408.5.7.5.4In a home, 2 of each kind at most per floor per stack; many commercial fixtures not allowed9.4.1, Table B.1As single stack9.4, Table B.1
Suitsour readingHouses and small buildings to 3 levels, any layoutAS1 1.0.1, 1.0.3Fixtures spread out or far from a stack; hospital, laboratory or kitchen fixtures; tall buildings8.2.2, Table 8.2.2(B)Bathrooms and toilet rooms whose fixtures group on one branch8.2.3, 8.5.7Wet rooms stacked over each other beside a stack: apartments, compact houses9.4, Table 9.5.1Taller apartments with stacked wet rooms, or more load on one DN 100 stack9.2.3, Table 9.7.2
Gainsour readingOne document with AS2 below ground; a vent on each pipe gives the most freedom in layoutAS1 1.0.3Any fixture, any layout, any height8.2.2Far fewer vents than fully vented for grouped fixtures8.5.7.1The least vent pipe: no trap, branch or relief vents9.2.1Single stack's connections kept while the load or the height grows9.2.3
Costsour readingA vent on most pipes; a relief vent once a stack serves 3 floors; no air admittance valve on the first stackAS1 Table 5, 5.6.2The most vent pipe, each rising above its fixture8.5.1.4Short pipes to the branch; a drop of 1.5 m at most8.5.7.5.2Short reach, limits per floor, a closed list of fixtures9.4, 9.5.1A relief vent the full height, and cross-vents9.6.2
Each AS/NZS 3500.2 system in detail →

G13/AS1 and AS2: the sizes to design to

C 2.5 mB 1.0 mA 600 mmStackDrain →← UpstreamNo connection
No branch may join inside these zones. A building of up to 3 levels, as drawn; up to 2 levels, B and C are each 500 mm. G13/AS1 4.7.2 a), Figure 7.
Trap water seal kept in use≥ 25 mmAS1 3.2.1
Fixture outlet to its trap's seal≤ 1.2 mAS1 3.3.1 b)
Stack's highest connection unvented, DN 100 / DN 80 / DN 32 to 656 / 1.5 / 3.5 mAS1 Table 5
DN 100 stack, whole stack / from one floor195 / 65 DUAS1 Table 4
Flattest graded pipe, DN 40 to 65 / DN 80 and 1001:40 / 1:60AS1 Table 4
Relief vent once a stack serves this many floors; it joins this far below the lowest branch3 · ≥ 300 mmAS1 5.6.2, 5.6.3 a)
Vent above a roof / above an opening / from a deck / from an air intake150 mm / 600 mm / 3 m / 5 mAS1 5.7.3
Gully trap dish above the ground, paved / unpaved≥ 25 / 75 mmAS2 3.3.1 a) i)
Overflow relief gully below the lowest fixture's overflow, Housing≥ 150 mmAS2 3.3.2 a)
Least drain, soil / waste water onlyDN 100 / DN 80AS2 3.6.2
Flattest drain, DN 100 / DN 1501:120 / 1:200AS2 Table 2
Drain vent from the head of the drain; branch drains longer than this are vented≤ 10 m · 10 mAS2 4.1.2, 4.1.4
Access point where a drain leaves the building, outside it≤ 2 mAS2 5.7.4 g)

Where the documents part

Places where G13 says less than it seems to, or where its words and its drawings disagree.

G13 never says what a level is

G13/AS1 covers buildings of 3 levels or less, and its base-of-stack zones change between 2 levels and 3, but the document defines neither level nor storey. Its own index files the drawing of those zones under three storey buildings, and a basement's plumbing is covered without saying whether the basement counts as a level.

G13/AS1 1.0.1, Figure 7, Index

3.5 m in the table, 1.5 m in the drawing

Table 5 lets the highest connection to a stack run 3.5 m unvented where the pipe is 32 to 65 mm. The drawing of a graded stack gives 1.5 m for any pipe of 80 mm or smaller. A small waste pipe longer than 1.5 m and no longer than 3.5 m passes one and fails the other.

G13/AS1 Table 5, Figure 8

Access points at least 50 m apart

G13/AS2 sets access points on straight drains at intervals of no less than 50 m for rodding points and 100 m for chambers. Read as written they are least spacings; the sense is plainly the most a run may go without one.

G13/AS2 5.7.4 f)

G13 requirements

Every requirement G13/AS1 and G13/AS2 state, numbered, so one can be pasted onto a sheet as it stands. Where the document states a condition, it can be answered N/A, and the answer prints.

Scope and water seals, G13/AS1 1.0

  1. Water seals protected Water seals are protected from pressure changes in the pipework, so foul air and gases cannot enter the building. G13/AS1 does this with a fully vented system, in which each fixture discharge pipe is generally vented.

    G13/AS1 1.0.3

Materials, G13/AS1 2.0 and G13/AS2 2.0

  1. Plumbing materials Pipes, fittings, traps and air admittance valves are made to the standards G13/AS1 Table 1 lists for their material.

    G13/AS1 2.1.1, G13/AS1 Table 1

  2. Drainage materials Drainage pipes and joints are made and installed to the standards G13/AS2 Table 1 lists for their material.

    G13/AS2 2.0.1, G13/AS2 Table 1

Water traps, G13/AS1 3.1 to 3.3

  1. A trap at every discharge point Every discharge point of a sanitary fixture or sanitary appliance has a water trap, to keep foul air from the plumbing out of the building.

    G13/AS1 3.1.1

  2. Traps can be cleaned A water trap is removable, can be dismantled, or has a cleaning eye.

    G13/AS1 3.1.2

  3. Water seal Under normal operating conditions a fixture trap keeps a water seal at least 25 mm deep.

    G13/AS1 3.2.1, G13/AS1 Figure 1

  4. Trap diameter A water trap is at least the diameter G13/AS1 Table 2 gives for the fixture it serves.

    G13/AS1 3.2.2, G13/AS1 Table 2

  5. Where a trap goes A water trap is as close as it can be to the fixture or appliance it serves, in the same room, with no more than 1.2 m of developed length between its water seal and the fixture's outlet or the appliance's discharge point.

    G13/AS1 3.3.1

  6. One trap for several outlets One water trap serves more than one outlet only within one space, and only for one or two adjacent domestic kitchen sinks with a dishwashing machine or with a waste disposal unit, or with both on a trap and discharge pipe of 50 mm; one or two adjacent laundry tubs with a clothes washing machine; or two adjacent basins, domestic kitchen sinks or laundry tubs.

    G13/AS1 3.3.2, G13/AS1 Figure 2

Floor wastes, G13/AS1 3.4

where there is a floor wasteG13/AS1 3.4.1

  1. Grating A floor waste outlet has a removable grating flush with the floor.

    G13/AS1 3.4.1

  2. Diameter A floor waste, and its water trap where it has one, is at least 40 mm in diameter.

    G13/AS1 3.4.2

  3. Where a floor waste discharges A floor waste is trapped, discharges 50 mm above the grating of a gully trap and is vented as Figure 3 shows; or is trapped, kept charged and discharges to the foul water plumbing as 4.5 and 5.0 set; or, where its only purpose is to take accidental overflows, has no trap and discharges to a safe place in the open air within the property boundary, with a guard against birds and vermin.

    G13/AS1 3.4.3, G13/AS1 Figure 3

  4. Floor waste stack Floor waste pipes combined into a floor waste stack are sized to G13/AS1 Table 3, and those joined to the stack need not be vented.

    G13/AS1 3.4.4, G13/AS1 Table 3, G13/AS1 Figure 3

  5. Floor waste stack vent A floor waste stack is open vented, independently of any other sanitary plumbing, and its vent ends as 5.7.4 sets.

    G13/AS1 3.4.5

  6. Keeping the seal charged A trapped floor waste discharging straight to the foul water plumbing keeps its water seal charged by a charge pipe of at least 32 mm from a tap, or from a hot or cold water relief valve draining over a tundish that keeps its air gap; by a mechanical trap priming device and its discharge pipe; or by a tap for washing the floor, in the same room and close to the floor waste. The charge pipe is at most 10 m long, and every trap charging system has backflow prevention to G12/AS1.

    G13/AS1 3.4.6, G13/AS1 Figure 4

Discharge pipes, G13/AS1 4.1 to 4.6

  1. Layout Discharge pipes take the most practicable route with the fewest bends.

    G13/AS1 4.1.1

  2. Access for cleaning Discharge pipes have access points for clearing blockages easily: where a soil discharge pipe joins a discharge stack, where a number of changes of direction occur, where junctions or bends are otherwise hard to reach, and at the base of every soil stack where it joins the drain.

    G13/AS1 4.2.1, G13/AS1 4.2.2

  3. Fixture discharge pipes A fixture discharge pipe is at least the diameter G13/AS1 Table 2 gives for its fixture, and gets no smaller in the direction of flow.

    G13/AS1 4.3.1, G13/AS1 Table 2

  4. Pipes taking more than one fixture A discharge pipe taking the discharge of more than one fixture is at least the diameter G13/AS1 Table 4 gives for its discharge units, the sum of Table 2's for every fixture it serves, at its gradient.

    G13/AS1 4.3.2, G13/AS1 Table 4

  5. Gradient A discharge pipe is no flatter than G13/AS1 Table 4 allows for its discharge units.

    G13/AS1 4.4.1, G13/AS1 Table 4

  6. Waste water fixtures A waste water fixture's discharge pipe goes to a gully trap, as G13/AS1 Figure 5 and G13/AS2 Figure 3 show, or to a discharge stack as 4.7 sets, and is vented as 5.0 and Table 5 require.

    G13/AS1 4.5.1, G13/AS1 4.5.2

  7. Soil fixtures A soil fixture's discharge pipe goes directly to the drain, as Figure 6 shows, or to a stack as 4.7 sets, and is vented as 5.0 and Table 5 require.

    G13/AS1 4.6.1, G13/AS1 4.6.2

  8. Junctions on soil branches A junction in a graded soil fixture branch discharge pipe raises each branch's entry at least 15° above the horizontal.

    G13/AS1 4.6.3, G13/AS2 Figure 1

Discharge stacks, G13/AS1 4.7

where there is a discharge stackG13/AS1 4.7.1

  1. Stack diameter A discharge stack is at least the diameter G13/AS1 Table 4 gives for its discharge units, the sum of Table 2's for every fixture it serves, at its gradient.

    G13/AS1 4.7.1 a), G13/AS1 Table 4

  2. Vertical stack vent A vertical stack carries on up past its highest branch connection as its discharge stack vent.

    G13/AS1 4.7.1 b), G13/AS1 Figure 7

  3. Positive pressure zone No discharge pipe joins a vertical stack, or the drain, inside the positive pressure zone near the stack's base that Figure 7 shows.

    G13/AS1 4.7.2 a), G13/AS1 Figure 7

  4. Two branches at one level Two branches entering a vertical stack at the same level come in through a double Y junction, with sweep entries or with entries at an included angle of 90°.

    G13/AS1 4.7.2 b), G13/AS1 Figure 9

  5. Branches at different levels Branches entering at different levels do not join inside the restricted entry zones Figure 9 (a) shows, except as Figure 9 (b) and (c) allow.

    G13/AS1 4.7.2 c), G13/AS1 Figure 9

  6. Base of a vertical stack The change of direction at the base of every vertical section of a stack is made with two nominal 45° bends, or one and a Y junction.

    G13/AS1 4.7.5

  7. Graded stack vent A graded stack has its discharge stack vent joined to the graded section downstream of the highest fixture, as Figure 8 shows.

    G13/AS1 4.7.1 c), G13/AS1 Figure 8

  8. Connections to a graded stack Connections to a graded stack do not enter opposite each other, nor within 450 mm of a bend.

    G13/AS1 4.7.3, G13/AS1 Figure 8

  9. Junctions on a graded stack A junction in a graded 100 mm stack raises each branch's entry at least 15° above the horizontal.

    G13/AS1 4.7.4, G13/AS2 Figure 1

Vent pipes, G13/AS1 5.1 to 5.5

  1. Venting Discharge pipes are vented where G13/AS1 Table 5 requires.

    G13/AS1 5.1.1, G13/AS1 Table 5

  2. Vents of fixtures to a gully trap The vents of fixtures that discharge to a gully trap or a grease trap are independent of any vent system joined directly to the foul water drainage.

    G13/AS1 5.1.2

  3. Kinds of vent pipe A vent pipe is a fixture vent, vertical or graded, ending as 5.7.1 or 5.8.1 sets; or a fixture vent rising to join a branch vent, a discharge stack vent or a relief vent at least 50 mm above the overflow level of the fixture it serves.

    G13/AS1 5.2.1, G13/AS1 Figure 10

  4. Vent diameter Fixture vents, branch vents, discharge stack vents and relief vents are at least the diameter G13/AS1 Table 6 gives.

    G13/AS1 5.3.1, G13/AS1 Table 6

  5. Vent gradient Fixture and branch vents rise from where they join the discharge pipe to the open air, or to an air admittance valve, at 1:80 or steeper.

    G13/AS1 5.4.1

  6. Vent on a waste pipe to a gully trap Where Table 5 requires a fixture vent on a fixture discharging to a gully trap, it joins the waste pipe between 75 mm and 3.5 m from the crown of the trap.

    G13/AS1 5.5.1, G13/AS1 Figure 11

  7. Vent on a pipe to a stack or the drain Where Table 5 requires a fixture vent on a fixture discharging to a stack or the drain, it joins: for a WC pan, at the pan's vent horn, or on the discharge pipe within 1.5 m of the crown of the trap and at least 300 mm above any bend at the base of a vertical drop; for a basin or bidet, between 75 mm from the crown of the trap and either 600 mm from it or the first bend; for any other fixture, between 75 mm and 1.5 m from the crown of the trap, and at least 300 mm above any bend at the base of a vertical drop.

    G13/AS1 5.5.2, G13/AS1 Figure 6, G13/AS1 Figure 11

Which pipes are vented, G13/AS1 Table 5

  1. Stack vent Every stack discharging to another stack or to a drain has an open vent sized to Table 6. An air admittance valve may vent a second or later stack only, since at least one open vent, the stack vent where it is the main drain vent, ventilates the drain.

    G13/AS1 Table 5, G13/AS2 Table 3

  2. Relief vent Every stack receiving discharges from 3 floor levels has a relief vent sized to Table 6, and relief vents are open vented.

    G13/AS1 Table 5

  3. Connections to a stack Every connection to a stack but the highest is vented, by an open vent or an air admittance valve sized to Table 6.

    G13/AS1 Table 5

  4. The highest connection The single highest connection to a stack is vented, by an open vent or an air admittance valve sized to Table 6, where its discharge pipe is longer than 6 m at 100 mm, 1.5 m at 80 mm, or 3.5 m at 32 to 65 mm.

    G13/AS1 Table 5

  5. Soil fixtures on an unvented branch drain Every soil fixture on an unvented branch drain is vented, by an open vent or an air admittance valve sized to Table 6.

    G13/AS1 Table 5

  6. Soil fixtures on a flat drain Every soil fixture on a vented drain, where the branch and the drain are flatter than 1:60, is vented by an open vent or an air admittance valve sized to Table 6.

    G13/AS1 Table 5

  7. Soil fixtures on a steeper drain A single soil fixture on a vented drain, where the branch and the drain are at 1:60 or steeper, is vented by an open vent or an air admittance valve sized to Table 6 where its discharge pipe is longer than 6 m at 100 mm or drops more than 2 m, or is longer than 1.5 m at 80 mm.

    G13/AS1 Table 5

  8. Fixtures discharging to a gully trap A fixture discharging to a gully trap is vented, by an open vent or an air admittance valve sized to Table 6, where it shares a waste pipe with another fixture or its own discharge pipe is longer than 3.5 m; and a 32 mm discharge pipe dropping more than 1.5 m has a 32 mm vent or an air admittance valve.

    G13/AS1 Table 5

  9. Main drain vent A main drain discharging to the sewer or to on-site disposal has an open vent of at least 80 mm.

    G13/AS1 Table 5, G13/AS2 Table 3

  10. Branch drain vent A branch drain on a vented drain that is longer than 10 m has its own open vent, sized to Table 6.

    G13/AS1 Table 5, G13/AS2 Table 3

Stack vents and relief vents, G13/AS1 5.6

where there is a discharge stackG13/AS1 4.7.1

  1. Stack vent diameter A discharge stack vent that is also the drain vent is at least 80 mm; any other stack vent is at least the diameter Table 6 gives.

    G13/AS1 5.6.1

  2. When a relief vent is needed A discharge stack serving fixtures or appliances on 3 floors has a relief vent, as Figure 7 shows.

    G13/AS1 5.6.2, G13/AS1 Figure 7

  3. The relief vent The relief vent joins the bottom of the stack at least 300 mm below the lowest discharge pipe it serves, at 45°, and rises at 1:80 or steeper to the discharge stack vent, or on its own to the open air; it is at least the diameter Table 6 gives.

    G13/AS1 5.6.3, G13/AS1 Figure 7

Where open vents end, G13/AS1 5.7

  1. Where open vents end Open vents end outside the building, at least 50 mm over the level at which the highest fixture they serve would overflow, with a guard against birds and vermin whose open area is at least 80% of the vent's cross-section.

    G13/AS1 5.7.1, G13/AS1 5.7.2

  2. Distances from the building An open vent serving discharge pipes joined directly to the drainage ends no nearer the building than 3 m above the ground; 600 mm above, and 3 m below and beside, a window or other opening; 150 mm above a roof; 3 m above, below and beside a deck with pedestrian access; 600 mm above, below and beside eaves or a parapet; and 5 m from an air intake in any direction.

    G13/AS1 5.7.3, G13/AS1 Figure 12

  3. Vents on waste pipes to a gully trap A fixture vent serving a waste pipe to a gully trap ends outside the building at least 900 mm from any opening into it, and is vented to the open air independently of any vent system joined directly to the drainage.

    G13/AS1 5.7.4

Air admittance valves, G13/AS1 5.8

where an air admittance valve is usedG13/AS1 5.8.1

  1. Where a valve may vent An air admittance valve vents a discharge pipe only where Table 5 allows one.

    G13/AS1 5.8.1, G13/AS1 Table 5

  2. Standard It is made to ASSE 1050, ASSE 1051, BS EN 12380 or AS/NZS 4936.

    G13/AS1 5.8.2

  3. Size It is at least the diameter Table 6 gives and no smaller than the vent pipe it serves; one that is part of a fixture trap vents only that trap.

    G13/AS1 5.8.3

  4. Where it goes It is upright, at least 100 mm above the weir of the fixture trap, where it can be reached for maintenance and inspection, will not freeze, is protected from damage and can take in enough air; inside a wall space it has ventilated openings of at least 1.5 times the area of the vent pipe.

    G13/AS1 5.8.4, G13/AS1 Figure 10

Installation and testing, G13/AS1 6.0 and 7.0

  1. Jointing PVC-U PVC-U pipe is jointed by the methods of AS/NZS 2032.

    G13/AS1 6.1.1

  2. Pipe supports Pipes are supported at centres no further apart than G13/AS1 Table 7 sets.

    G13/AS1 6.2.1, G13/AS1 Table 7

  3. Hot discharges in PVC-U PVC-U pipe carrying discharges hotter than 60°C is supported as AS/NZS 2032 6.3.2 sets.

    G13/AS1 6.2.2

  4. Thermal movement The plumbing takes up the lengthwise movement of its pipes as their temperature changes, without failure: copper and PVC-U pipes have expansion joints, and PVC-U pipes follow AS/NZS 2032 6.4.

    G13/AS1 6.3.1

  5. Sleeves and lagging At supports, and where pipes pass through walls and floors without an expansion joint, the movement is taken up by pipe sleeves or a durable, flexible lagging.

    G13/AS1 6.3.2

  6. Fire separations Pipes passing through a fire separation are fire stopped as C/AS2 4.4 sets.

    G13/AS1 6.4.1

  7. Testing the plumbing All the above-ground sanitary plumbing is tested for watertightness, by a water test or an air test.

    G13/AS1 7.1.1

Drains, G13/AS2 1.0 to 3.2

  1. Fill Fill, placed as Figure 7 shows, is bedding of clean, granular, non-cohesive material; selected fill of fine-grained soil or granular material free of topsoil and rubbish; or ordinary fill of excavated material. Bedding and selected fill have no particle larger than 20 mm.

    G13/AS2 2.1.1, G13/AS2 Figure 7

  2. Layout To keep it from blocking, the drainage has a simple layout with the fewest changes of direction, bends of the largest radius practical, and straight runs between bends and junctions, both in plan and in section.

    G13/AS2 3.1.1

  3. Junctions Every connection to a drain, vent pipes apart, is a junction with an upstream angle of no more than 45°, laid in the direction of flow; in a graded drain it raises the branch drain's entry at least 15° above the horizontal.

    G13/AS2 3.2.1, G13/AS2 Figure 1

Gully traps, G13/AS2 3.3.1

where there is a gully trapG13/AS2 3.3.1

  1. Gully traps A gully trap keeps out surface water and anything likely to block it, and is within the legal boundary of the land the building is on.

    G13/AS2 3.3.1

  2. Dish height The overflow level of the gully dish is at least 25 mm above paved surfaces, or 75 mm above unpaved surfaces.

    G13/AS2 3.3.1 a), G13/AS2 Figure 2

  3. Grating, outlet and seal It has a grating that lets the drain surcharge; an outlet pipe of at least 100 mm; a water seal at least 65 mm deep, its top no more than 600 mm below the top of the dish; at least one discharge pipe into it, so its seal does not dry out; and at least 600 mm of clear access space above the dish.

    G13/AS2 3.3.1 b), G13/AS2 3.3.1 c), G13/AS2 3.3.1 d), G13/AS2 3.3.1 e), G13/AS2 3.3.1 h), G13/AS2 3.3.1 j), G13/AS2 Figure 3

  4. Waste pipes into it The waste pipes discharging to it are arranged so it can be cleaned easily, and end at least 20 mm above the water seal and at least 20 mm below the grating.

    G13/AS2 3.3.1 f), G13/AS2 3.3.1 g)

  5. Bedding It is bedded and backfilled in concrete at least 75 mm thick all round the dish, separated from the building foundation, where it is likely to be damaged; elsewhere in compacted bedding material as 2.1.1 describes.

    G13/AS2 3.3.1 i)

Overflow relief, G13/AS2 3.3.2

where the building is used for HousingG13/AS2 3.3.2

  1. Overflow relief gully A building used for Housing has at least one gully trap for overflow relief, with the top of its dish at least 150 mm below the overflow level of the lowest sanitary fixture the drainage serves.

    G13/AS2 3.3.2 a)

  2. Its grating and place That gully trap has a grating that lets the drain surcharge, is in a visible position, and is installed so surcharge cannot get into or under buildings.

    G13/AS2 3.3.2 b), G13/AS2 3.3.2 c), G13/AS2 3.3.2 d)

Grease traps, G13/AS2 3.4

where a grease trap is needed: sinks discharging to a soak pit, or, other than in Housing, waste water likely to carry greaseG13/AS2 3.4.1, G13/AS2 3.4.2

  1. Where a grease trap is needed A grease trap is provided on any discharge pipe serving sinks where the foul water discharges to a soak pit, and, in buildings other than Housing, where the waste water is likely to carry grease.

    G13/AS2 3.4.1, G13/AS2 3.4.2

  2. Capacity A grease trap holds at least twice the capacity of all the fixtures and appliances discharging to it, and never less than 100 litres, as Figure 4 shows.

    G13/AS2 3.4.3, G13/AS2 Figure 4

  3. Restaurants and cafes For a restaurant or cafe, the grease trap holds at least 5 litres for each person seating is provided for, and no less than 3.4.3 requires.

    G13/AS2 3.4.4

  4. Outside the building A grease trap outside the building is laid out as Figure 4 shows, with the top of its outlet junction brought up to finished ground level and fitted with a watertight rodding point access cover.

    G13/AS2 3.4.5, G13/AS2 3.4.6, G13/AS2 Figure 4, G13/AS2 Figure 10

  5. Other kinds A grease trap of another kind, such as one that separates or digests grease, is approved by the network utility operator as G14/VM1 1.2 requires.

    G13/AS2 3.4.7

Gradient and diameter of drains, G13/AS2 3.5 and 3.6

  1. Even gradient Drains are laid at an even gradient, with nothing obstructing the flow, and at the steepest gradient practicable.

    G13/AS2 3.5.1, G13/AS2 3.5.2

  2. Least gradient A drain is no flatter than G13/AS2 Table 2 allows for its discharge units, counted from G13/AS1 Table 2.

    G13/AS2 3.5.3, G13/AS2 Table 2

  3. Diameter A drain gets no smaller in the direction of flow, and is at least 100 mm, or 80 mm where it serves only waste water fixtures, and at least the diameter G13/AS2 Table 2 gives for its load.

    G13/AS2 3.6.1, G13/AS2 3.6.2, G13/AS2 3.6.3, G13/AS2 Table 2

Drain ventilation, G13/AS2 4.0

  1. Ventilated The drainage is ventilated, to let air flow and keep foul air from building up.

    G13/AS2 4.1.1

  2. Which drains Every main drain, and every branch drain longer than 10 m, is ventilated as G13/AS2 Table 3 sets.

    G13/AS2 4.1.2, G13/AS2 Table 3

  3. Where the drain vent joins The drain vent joins so that less than 10 m of drain is upstream of it, downstream of the discharge connection nearest the head of the drain and no more than 10 m from it. An open discharge stack vent within 10 m of the head of the drain may be the drain vent.

    G13/AS2 4.1.3, G13/AS2 4.1.4, G13/AS2 4.1.5, G13/AS2 Figure 5

  4. Drain vent size A main drain vent is at least 80 mm and ends as G13/AS1 5.7.3 sets; a branch drain vent is sized to G13/AS1 Table 6.

    G13/AS2 4.2.1, G13/AS2 4.2.2

Jointing and construction, G13/AS2 5.1 to 5.6

  1. Rigid pipes Rigid pipes have flexible joints, to resist damage from uneven settlement.

    G13/AS2 5.1.1

  2. Jointing PVC-U drains PVC-U pipes and fittings are jointed by the methods of AS/NZS 2032.

    G13/AS2 5.1.2

  3. Loads and support Drains are built to carry the loads likely on them, as often as they come, without collapse, undue damage or undue deflection, and are supported so that uneven settlement or a sagging span cannot leave them flatter than Table 2 requires.

    G13/AS2 5.2.1, G13/AS2 Figure 7

  4. Levelling devices Drains laid at 1:80 or flatter are set with verifiable levelling devices, for an even and accurate gradient.

    G13/AS2 5.2.2

  5. Bedding and backfill Drains are bedded and backfilled by the methods Figure 7 shows.

    G13/AS2 5.3.1, G13/AS2 Figure 7

  6. Ground needing specific design Where the trench is in or above peat, likely to scour in unstable soil, nearer a building foundation than 5.6.1 allows, or under more than 2.5 m of cover, the drain is subject to specific design.

    G13/AS2 5.3.1, G13/AS2 5.3.2

  7. Trench width A trench is at least the pipe's diameter plus 200 mm wide, and no more than 600 mm wide at the top of the pipe unless the pipes are covered with concrete, as Figure 7 (c) shows.

    G13/AS2 5.4.1, G13/AS2 Figure 7

  8. Placing and compacting Base bedding is placed and compacted before the pipes are laid; side bedding, and cover bedding where used, is compacted to 300 mm above the pipe.

    G13/AS2 5.5.1, G13/AS2 5.5.2

  9. Trenches beside a foundation Beside a light timber framed or concrete masonry building built to NZS 3604 or NZS 4229 under B1/AS1, a trench open for no more than 48 hours is no nearer the underside of any foundation than V, as Figure 8 shows; open for longer, it is at least 3V away, in any ground but rock.

    G13/AS2 5.6.1, G13/AS2 Figure 8

Access points, G13/AS2 5.7

  1. Easy access Drains, other than those 5.8 and 5.9 cover, are laid to allow easy access for maintenance and for clearing blockages.

    G13/AS2 5.7.1

  2. Access points Drains have access points for cleaning and clearing blockages, built to keep out ground water and tree roots: access chambers, inspection chambers, rodding points or inspection points, as Figures 9–12 show.

    G13/AS2 5.7.2, G13/AS2 5.7.3

  3. Where access points go Access points are placed immediately before the drain's outfall; immediately inside the boundary of the property served; at every junction of one drain with another, except where the branch drain is shorter than 2 m and serves only a gully trap; at every change of direction in plan of more than 45°; at every change of gradient of more than 45°; at intervals on straight runs of no less than 50 m with rodding points or 100 m with chambers or inspection points; and within 2 m outside the building where a drain goes under it or comes out from under it.

    G13/AS2 5.7.4

Drains under a building, G13/AS2 5.8 and 5.9

where a drain runs under the buildingG13/AS2 5.8.1

  1. Drains under a building A drain under a building is straight and of even gradient, at least 25 mm clear of the building foundation, and sleeved or wrapped in a durable, flexible material where it passes through concrete.

    G13/AS2 5.8.1

  2. Under a slab on ground Under a building with a concrete slab on the ground floor, the drain also has 50 mm of clearance from the top of the pipe to the underside of the slab, and junctions under the building join at no more than 45°, as Figure 13 shows.

    G13/AS2 5.8.2, G13/AS2 Figure 13

  3. Rodding point under a building Where two or more soil fixtures join a branch drain under the building, a sealed floor level rodding point is provided downstream of the highest fixture connection, as Figure 10 and Figure 13 show.

    G13/AS2 5.9.1, G13/AS2 Figure 10, G13/AS2 Figure 13

  4. Access points inside An access point inside a building is in a space that meets the isolation and ventilation requirements for spaces with soil fixtures, and it may be in a space that has a soil fixture.

    G13/AS2 5.9.2, G13/AS2 5.9.3

Disused drains, G13/AS2 5.10

where a drain, or part of one, is no longer neededG13/AS2 5.10.1

  1. Disconnecting a drain A drain, or part of one, no longer needed is disconnected at its junction with the live drain or at the property boundary, and the live drain is sealed: a purpose-made junction by a tight-fitting plug fixed in place that does not protrude into the live drain; an in-situ junction, where the branch was inserted into an existing pipe, by cutting the branch off as close to the junction as practicable and fitting a purpose-made cap, plug or stopper, or by replacing that length of pipe.

    G13/AS2 5.10.1, G13/AS2 5.10.2

Testing the drains, G13/AS2 6.0

  1. Testing the drains Every section of the drainage is tested for watertightness, by a water test or an air test.

    G13/AS2 6.1.1

  2. A disused drain brought back A disused drain being brought back into use is tested first, to verify that it is sound.

    G13/AS2 6.1.4

  3. Building over a drain Where the building is to be built over an existing drain, the drain is verified as sound both before and after construction.

    G13/AS2 6.1.5

Show on drawings

What the consent drawings and specification show for the sanitary plumbing and the drains. Each line is something to draw, label or name, and each serves a requirement on the Requirements face.

G13 requirements to show on the drawings

  1. G13/AS1 Table 1, G13/AS2 Table 1
  2. G13/AS1 3.1, G13/AS1 3.3.1, G13/AS1 Table 2
  3. G13/AS1 3.1.2, G13/AS1 3.2.1
  4. G13/AS1 3.3.2
  5. G13/AS1 3.4.1, G13/AS1 3.4.2, G13/AS1 3.4.3
  6. G13/AS1 3.4.4, G13/AS1 3.4.5
  7. G13/AS1 3.4.6
  8. G13/AS1 4.1, G13/AS1 4.3, G13/AS1 4.4
  9. G13/AS1 4.5.1, G13/AS1 4.6.1
  10. G13/AS1 4.2.2
  11. G13/AS1 4.6.3, G13/AS1 4.7.4, G13/AS2 3.2.1
  12. G13/AS1 4.7.1, G13/AS1 5.6.1, G13/AS1 Table 5
  13. G13/AS1 4.7.2, G13/AS1 4.7.3, G13/AS1 Figure 7, G13/AS1 Figure 9
  14. G13/AS1 4.7.5
  15. G13/AS1 5.1, G13/AS1 5.2, G13/AS1 5.3, G13/AS1 5.4, G13/AS1 5.5, G13/AS1 Table 5, G13/AS1 Table 6
  16. G13/AS1 5.6.2, G13/AS1 5.6.3
  17. G13/AS1 5.7
  18. G13/AS1 5.8
  19. G13/AS1 6.2, G13/AS1 Table 7
  20. G13/AS1 6.3
  21. G13/AS1 6.1.1, G13/AS2 5.1
  22. G13/AS1 6.4.1
  23. G13/AS2 3.1.1
  24. G13/AS2 3.5, G13/AS2 3.6, G13/AS2 Table 2
  25. G13/AS2 5.2.2
  26. G13/AS2 3.3.1
  27. G13/AS2 3.3.2
  28. G13/AS2 3.4
  29. G13/AS2 4.1, G13/AS2 4.2, G13/AS1 Table 5
  30. G13/AS2 2.1.1, G13/AS2 5.2.1, G13/AS2 5.3, G13/AS2 5.4, G13/AS2 5.5, G13/AS2 Figure 7
  31. G13/AS2 5.6.1, G13/AS2 Figure 8
  32. G13/AS2 5.7, G13/AS2 5.9.2
  33. G13/AS2 5.8
  34. G13/AS2 5.9.1
  35. G13/AS2 5.10
  36. G13/AS1 7.1, G13/AS2 6.1
  37. G13/AS1 4.7.2, G13/AS1 Figure 7, G13/AS1 Figure 9

Clear every tick on this list?

Reading

What the documents say about their requirements: their COMMENTs, what they cover, and the methods they offer. None of it prints.

Scope and water seals, G13/AS1 1.0

What G13/AS1 coversG13/AS1 1.0.1, G13/AS1 1.0.2
G13/AS1 covers the above-ground gravity sanitary plumbing of a building of up to 3 levels, basements included: every foul water pipe in or on the building. It does not cover the specialised fixtures and appliances of buildings such as hospitals, laboratories and factories, or wastes that have to be treated before they can go to a sewer.
Why each fixture is ventedG13/AS1 1.0.3 COMMENT
Venting each fixture discharge pipe on its own leaves the most freedom in how the discharge pipes are arranged and how long they run.

Materials, G13/AS1 2.0 and G13/AS2 2.0

WaterMark productsG13/AS1 2.1.1 COMMENT, G13/AS2 2.0.1 COMMENT
A product certified and marked under the Australian WaterMark Certification Scheme, and listed on its product database, may be taken to meet the materials paragraphs of G13/AS1 and G13/AS2 for its intended purpose.

Water traps, G13/AS1 3.1 to 3.3

Bath trapsG13/AS1 3.1.2 COMMENT
A bath trap needs no removable panel for access.
Nominal sealsG13/AS1 3.2.1 COMMENT
Traps are made with nominal seals deeper than this least depth, and the document advises testing the system under load to be sure the least depth holds.
Short trap pipesG13/AS1 3.3.1 COMMENT
Waste can build up on the walls of the pipe to a trap and let smells into the building through the outlet; a short pipe makes that less likely. A trap may be under the floor, or in the ceiling space of the floor below.
Commercial sinksG13/AS1 3.3.2 COMMENT
Two adjacent commercial sinks may not share a trap: foul water in one could contaminate the other while food is being prepared in it.

Floor wastes, G13/AS1 3.4

What a floor waste is forG13/AS1 3.4.1 COMMENT
The flush grating lets people move safely and easily across the floor. A floor waste here is not for receiving liquid or excreted human waste.
Why it is vented on its ownG13/AS1 3.4.5 COMMENT
An independent vent lowers the risk of foul air and gases getting into the floor waste system.
Backflow protectionG13/AS1 3.4.6 COMMENT
An air gap, or a backflow prevention device, gives the backflow protection.

Discharge pipes, G13/AS1 4.1 to 4.6

Access fittingsG13/AS1 4.2.2 COMMENT
Proprietary fittings that give access into the pipe should be used at these points.
Why a least gradientG13/AS1 4.4.1 COMMENT
The least gradients are there to keep the pipes from blocking.

Discharge stacks, G13/AS1 4.7

Why the zoneG13/AS1 4.7.2 COMMENT
Where a stack bends sharply at its base, a hydraulic jump can form in the horizontal pipe downstream of the bend, and the high pressure there can blow out the water seals of a branch joined in that zone.

Vent pipes, G13/AS1 5.1 to 5.5

Why independentG13/AS1 5.1.2 COMMENT
An independent vent system keeps sewer gases from escaping through the waste pipes that discharge to a gully trap.

Stack vents and relief vents, G13/AS1 5.6

Long relief ventsG13/AS1 Table 6 Note
Table 6's relief vent sizes hold for a relief vent of up to 12 m of developed length, and a longer one is outside the table.

Where open vents end, G13/AS1 5.7

Why above the overflowG13/AS1 5.7.2 COMMENT
Ending the vent above the overflow level keeps it from carrying foul water if the discharge pipe blocks.
Why the distancesG13/AS1 5.7.3 COMMENT
The distances make it less likely that foul air from the drainage gets into the building.
Why these are less restrictedG13/AS1 5.7.4 COMMENT
A waste pipe to a gully trap is not joined directly to the drainage, so is not itself a source of foul air, and its vent may end nearer an opening; it is kept independent so sewer gases cannot escape through it.

Air admittance valves, G13/AS1 5.8

What a valve doesG13/AS1 5.8.4 COMMENT
Valves can save much of the vent pipework and many roof penetrations, but the pipes are still sized as G13/AS1 sets. A valve protects against siphonage, and may not protect a trap's seal where the pressure is positive.

Installation and testing, G13/AS1 6.0 and 7.0

Why supportsG13/AS1 6.2 COMMENT
Supports keep the pipe from sagging to a gradient flatter than Table 4's least.
ExpansionG13/AS1 6.3 COMMENT
PVC-U lengthens noticeably as it warms, and expansion joints placed with fixed and sliding supports keep the movement from damaging pipes and fixtures.
Test methodsG13/AS1 7.1.2, G13/AS1 7.1.3
The water test of AS/NZS 2032, and air tests to AS/NZS 3500.2 15.3 or E1/VM1 8.3, are acceptable methods.

Drains, G13/AS2 1.0 to 3.2

What G13/AS2 coversG13/AS2 1.0.1, G13/AS2 1.0.2
G13/AS2 covers below-ground gravity foul water drains of up to 150 mm in diameter. It does not cover drainage of wastes that have to be treated before they can go to a sewer, which G14/VM1 does.

Gully traps, G13/AS2 3.3.1

Watertight connectionsG13/AS2 3.3.1 COMMENT
The waste pipe connections to a gully trap have to stay watertight, so ground and surface water cannot get in.
Cleaning by handG13/AS2 3.3.1 h) COMMENT
Keeping the seal no deeper than that lets the gully trap be cleaned by hand.

Overflow relief, G13/AS2 3.3.2

HousingG13/AS2 3.3.2 COMMENT
Housing is a classified use defined in Clause A1 of the Building Code.

Gradient and diameter of drains, G13/AS2 3.5 and 3.6

Steepest practicableG13/AS2 3.5.2 COMMENT
A drain that can practicably be laid steeper is not laid flatter.

Drain ventilation, G13/AS2 4.0

The head of the drainG13/AS2 4.1.4 COMMENT
The head of the drain is the point of the drainage furthest from the outfall.

Jointing and construction, G13/AS2 5.1 to 5.6

Which devicesG13/AS2 5.2.2 COMMENT
Laser and dumpy levels are the devices recommended.

Access points, G13/AS2 5.7

Rodding points preferredG13/AS2 5.7.3 COMMENT
Rodding points are preferred to inspection points in landscaped or sealed areas and inside buildings.
The intervalsG13/AS2 5.7.4 f)
5.7.4 f) sets its intervals as no less than 50 m and 100 m, which read literally is a least spacing, where every other item in the list says where an access point goes. The design on this page reads them as the longest straight run between access points.

Drains under a building, G13/AS2 5.8 and 5.9

DurabilityG13/AS2 5.8.2 COMMENT
A drain under a building has to meet the durability performance of B2.3.1 (a): no less than the life of the building, and not under fifty years.
Where those requirements areG13/AS2 5.9.2 COMMENT
G1/AS1 and G4/AS1 set those isolation and ventilation requirements.

Disused drains, G13/AS2 5.10

Why it mattersG13/AS2 5.10.2 COMMENT
An old branch drain badly disconnected can let a great deal of ground water into the drainage.

Testing the drains, G13/AS2 6.0

Test methodsG13/AS2 6.1.1 COMMENT, G13/AS2 6.1.2, G13/AS2 6.1.3
Testing before backfilling makes leaks easy to find. The water test of AS/NZS 2032 Section 7 for PVC-U drains, and air tests to AS/NZS 3500.2 15.3 or E1/VM1 8.3, are acceptable methods.

Terminology

The words the plans, the report and the requirements lean on, as G13's Definitions give them.

Access chamberDefinitions
A chamber with room to work at the level of the drain, which the drain passes through as an open channel or as a pipe with an inspection point.
Access pointDefinitions
A place to get into a drain or discharge pipe to inspect, clean or maintain it: a cleaning eye, inspection point, rodding point, inspection chamber or access chamber.
Air admittance valveDefinitions
A valve that lets air into the plumbing or drainage but not out, to limit changes of pressure in it.
Branch discharge pipeDefinitions
A discharge pipe serving one or more fixture discharge pipes on one floor.
Branch vent pipeDefinitions
A vent pipe serving two or more fixture vent pipes.
Cleaning eyeDefinitions
A small access point, usually part of a fitting or a trap.
Combined waste pipeDefinitions
A discharge pipe serving two or more waste pipes.
Developed lengthDefinitions
The whole length along the centre line of a pipe, its fittings and bends included.
Diameter (or bore)Definitions
The nominal internal diameter.
Discharge pipeDefinitions
Any pipe that carries the discharge from sanitary fixtures or sanitary appliances.
Discharge stackDefinitions
A discharge pipe with one or more discharge pipes connected to it, vented at one end by a discharge stack vent.
Discharge stack ventDefinitions
A vent pipe connected to the top of a discharge stack.
Discharge unitDefinitions
The unit the load on the plumbing is measured in, from how fast, how long and how often a sanitary fixture or appliance discharges.
DrainDefinitions
A pipe normally laid below ground, with its fittings and equipment, that carries foul water or surface water to an outfall.
Drain vent pipeDefinitions
Any pipe that lets air into and out of the drain and the sewer.
FixtureDefinitions
An article that stays permanently attached to a building and forms part of it.
Fixture discharge pipeDefinitions
A discharge pipe carrying the waste from one sanitary fixture or appliance to a branch discharge pipe, a discharge stack, or straight to a drain. The pipes that are part of an appliance are not included.
Fixture vent pipe (trap vent)Definitions
A vent pipe connected to a fixture discharge pipe or to the fixture itself.
Floor wasteDefinitions
An outlet at the low point of a graded floor, or in a level floor, that takes accidental or intentional discharges.
Floor waste pipeDefinitions
A pipe taking the discharge from a floor waste outside the building, or into the foul water drainage or the sanitary plumbing.
Foul waterDefinitions
The discharge from any sanitary fixture or sanitary appliance.
Foul water drainage systemDefinitions
The drains, joints and fittings, normally underground, that carry the water from the plumbing system to an outfall.
GradedDefinitions
A floor or pipework laid to a slope or gradient.
GradientDefinitions
Inclination, as the ratio or percentage of rise to horizontal distance.
Grease trapDefinitions
A device that catches grease in a foul water discharge.
Gully trapDefinitions
A fitting that stops foul air escaping from the drainage and takes the discharge from waste pipes.
Inspection chamberDefinitions
A chamber with room to work at ground level, which the drain passes through as an open channel or as a pipe with an inspection point.
Inspection pointDefinitions
A removable cap at the level of the drain, for cleaning and inspecting the drainage.
Network utility operatorDefinitions
A person who runs, or proposes to run, a network such as a drainage or sewerage system, a water supply, gas, electricity or telecommunications.
OutfallDefinitions
The part of the disposal system that receives the water from the drainage. For foul water it may be a sewer or a septic tank.
Plumbing systemDefinitions
The pipes, joints and fittings above ground that carry foul water to the foul water drain, vent pipes included.
Relief ventDefinitions
A vent pipe connected to a discharge stack below its lowest branch connection, which joins the stack vent at its upper end or ends as an open vent.
Rodding pointDefinitions
A removable cap at ground level, for cleaning and inspecting the drainage.
Sanitary applianceDefinitions
An appliance used for sanitation that is not a sanitary fixture, such as a dishwasher or a washing machine.
Sanitary fixtureDefinitions
Any fixture used for sanitation: a toilet, urinal, bidet, bath, shower, basin, sink or tub.
SewerDefinitions
A drain under the control of, or maintained by, a network utility operator.
Soil fixtureDefinitions
A sanitary fixture made to receive human excreta: a water closet pan, a urinal, a bedpan disposal unit, a slop sink or a water-flushed sanitary towel disposal unit.
Vent pipeDefinitions
A pipe that protects water seals, open to the air or fitted with an air admittance valve at its upper end, and connected to a discharge pipe at its lower end.
Waste pipeDefinitions
A discharge pipe carrying the discharge from waste water fixtures to a gully trap.
Waste water fixtureDefinitions
A sanitary fixture or appliance that receives wastes and is not a soil fixture.
Water sealDefinitions
The depth of water a water trap can hold.
Water trapDefinitions
A fitting that holds a depth of water to stop foul air and gases from the plumbing or the drainage getting into a building.

Educational: confirm with your BCA and the current documents. This tool sizes and checks what you draw against G13/AS1 and G13/AS2; whether a design complies is the building consent authority's finding.

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