Testing Plumbing & Drainage Systems – What’s Mandatory in NSW 2025

Proper testing of plumbing and drainage systems is not optional in NSW — it’s a legal requirement under the Plumbing and Drainage Act 2011 and Plumbing and Drainage Regulation 2017. Skipping or doing it incorrectly can result in failed inspections, rectification orders, fines, and costly delays at handover.

This guide covers exactly what’s mandatory in 2025 for Sydney and metropolitan NSW (Building Commission NSW area), including the key tests from AS/NZS 3500 series (2025 editions).

01When Testing Is Mandatory (NSW Rules 2025)

You must book an inspection (and perform the required tests) for most regulated plumbing and drainage work before covering or handover. Building Commission NSW operates an audit-based system — not every job is physically inspected, but you must submit a Notice of Work (NoW) and book inspection slots for:

• New sewer/water connections
• Major drainage alterations
• Hot water system installations
• Backflow prevention devices (RPZD)
• Recycled/rainwater systems
• Any performance solution work (non-DTS)

Minor work (e.g., replacing a tap, fixing a leak) usually does not require testing/inspection unless part of larger regulated work.

02Mandatory Tests from AS/NZS 3500:2025

The test that is most often priced wrong is the water service one, so start there.

Cold water services — AS/NZS 3500.1:2025 Clause 18.3.1. A water service shall not show any leakage when subjected to a hydrostatic pressure of 1 500 kPa for not less than 30 minutes. Note what that is not: it is not 1.5 times working pressure, it is not held for an hour, and there is no permitted pressure drop. The test is done on installed piping before burial or concealment, and on pipe systems with elastomeric seals the piping is backfilled with the joints left exposed until the test is finished.

• Flush first. Clause 18.2 requires the system to be flushed until the water runs completely clear before the pressure test.
• Storage tanks other than rainwater tanks are filled until they overflow for not less than 1 minute (Clause 18.3.2).
• Commissioning under Clause 18.6 means checking the operation of all valves, cisterns, taps and pressure-relief valves, not just passing the pressure test.
• Rainwater services are flushed and hydrostatically tested under Clause 16.7.1.
• Fire services may be tested at a higher pressure and for longer by the network utility operator, so check the authority requirement before you price it.

Sanitary plumbing and drainage — AS/NZS 3500.2:2025 Section 15. These are nothing like the water service test, and using the water figures here is both wrong and capable of damaging the pipework. You have three options: hydrostatic, air pressure, or vacuum.

Hydrostatic test (Clause 15.2). Non-drinking water may be used. Fill the section as follows:

• Sanitary drainage: to a height of not less than 1 m above the soffit at the highest point of the section being tested
• Sanitary plumbing: to the spill level of the highest fixture, or the flood level of the lowest sanitary fixture, whichever is higher
• In either case, not exceeding 3 m at the lowest point of the test section

Hold the pressure without leakage for at least 15 minutes. If it leaks, find it, repair it and retest the section. Where the water authority has restrictions in place, hydrostatic testing may not be permitted at all, and an air or vacuum test is used instead.

Air pressure test (Clause 15.3). Cap and seal every inlet, outlet and access opening, then introduce air slowly:

• Apply an initial test pressure of approximately 15 kPa, then shut off the pump and supply valve
• Let the pressure stabilise for at least 3 minutes while you check for leaks
• Then let it fall to 10 kPa and start timing, over the minimum duration set by pipe size and test length in Table 15.3.2
• The drop must not exceed 3 kPa over that duration (Clause 15.3.3)

The durations are short at small sizes and long at large ones. A DN100 line up to 200 m needs 2 minutes; DN300 over 300 m needs 29 minutes. A vacuum test under Clause 15.4 follows the same 15 kPa starting point.

What this means for a quote. The old rule of thumb of "30 kPa for 3 minutes" is not in the standard. Pricing a large-diameter air test at 3 minutes when the table calls for 29 will not cover the labour, and testing at double the correct pressure risks the joints.

Stormwater is covered by AS/NZS 3500.3:2025, with a visual inspection of gutters and downpipes alongside the pipework test.

Heated water services are covered by AS/NZS 3500.4:2025, which sets the pressure test and the temperature commissioning. Two separate temperatures matter, and they pull in opposite directions:

• Storage (Clause 1.11.2). To limit legionella growth an installation shall store water at not less than 60 °C, or use a water heater satisfying AS 3498:2020 Clause 7.2 in Australia. Note the second limb: a compliant temperature-limited heater is an alternative path, not a breach.
• Delivery (Clause 1.11.1). A separate limit applies to sanitary fixtures used for personal hygiene purposes, and it is tighter in buildings housing vulnerable occupants. Take the figure for your building class from Part 4 rather than assuming one number across a site.

Commissioning means proving both, not just passing the pressure test.

03Who Performs the Tests & Inspection Booking

• Plumber: Can perform basic tests (air/hydrostatic) and visual checks.
• Subcontract specialist (recommended for large/complex jobs): Required for high-pressure hydrostatic, flow/pressure commissioning, and certification/report.
• Book via MyInspections Gateway (Building Commission NSW metropolitan areas) — free NoW submission, but inspection fees apply (see below).
• Regional NSW: Contact local council (fees/process similar).

04Current Inspection Fees (FY 2025–2026 – Metropolitan NSW)

Fees are set by clause 13 and Schedule 1 of the Plumbing and Drainage Regulation 2017 and are charged per inspection, not bundled. Current figures published by Building Commission NSW for FY 2026–27:

• Standard inspection (work not covered elsewhere in the Schedule): $136
• Performance solution — initial inspection: $334
• Performance solution — each additional inspection: $199
• After hours — weekend, public holiday, or a weekday before 8am or after 4pm: $1,124

No fee for NoW or Certificate of Compliance submission.

05Practical Estimating Checklist for Sydney Jobs

• Standard house (new sewer, hot water): Allow $210–$420 (1–2 inspections)
• Large/multi-storey (performance solution): Allow $430–$800+ (3–5 inspections)
• Equipment: Test pump (Rothenberger RP50), calibrated gauges, plugs/caps — hire if not owned ($100–$300/day)
• Documentation: Photos, logs, pressure charts — required for Certificate of Compliance

At SNZ Plumbing Estimating, we include all mandatory testing and inspection fees in every quote — no surprises, full compliance.

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06Related reading

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