Test newly laid drainage pipes while all pipes and joints remain exposed, before backfilling, pouring concrete or putting the drain into service. An appropriately licensed plumber should inspect and isolate the section, conduct the applicable air or water watertightness test, repair any defect and retest the complete section.
Prepare the test section
Inspect the exposed drainage for:
- cracked, distorted or damaged pipes and fittings
- misaligned, incomplete or contaminated joints
- debris that could prevent test plugs from sealing
- jointing materials that have not completed the manufacturer’s specified curing time.
The plumber will divide the installation into suitable test sections and seal every branch, opening and connection with correctly sized, pressure-rated test plugs.
Test plugs can eject forcefully. They must be installed and restrained according to the manufacturer’s instructions, with people kept clear of the ejection path. Homeowners should limit their involvement to visual observation; plug installation and pressure testing should be left to an appropriately licensed plumber.
Conduct the air or water test
Use the method and acceptance criteria required by the applicable NCC provisions, AS/NZS 3500.2, approved project documents and inspecting authority. Whether an air or water test is appropriate depends on those requirements and the installation, not homeowner preference.
For an air test, approved equipment introduces air gradually into the sealed section. After the reading stabilises, a calibrated gauge is monitored for the specified test period.
For a water test, the plumber seals the lower openings and fills the section to the prescribed water head. Exposed pipe joints are checked for leaks, and any water loss is assessed against the applicable acceptance criteria.
A pressure drop does not always mean a pipe or joint is leaking. The plumber should first check the plugs, temporary connections, gauge and test equipment; temperature changes can also affect air-test readings.
Do not use test pressures, water heads or durations copied from overseas guidance or another project. Excessive pressure or water head can damage the drainage and cause plugs to eject.
If the drain fails
Do not conceal or use a failed drainage section. After checking the test setup, the licensed plumber should locate and repair the defect, then repeat the complete test until the section meets the applicable criteria.
Record the section, test method, readings, duration and result. Any required inspection or compliance documentation must be completed before the drain is covered or commissioned. NSW requirements vary by project and approval pathway, so confirm them with the relevant regulator, local authority or appointed certifier.
Contact our licensed Sydney plumbing team to complete or verify the required test before newly installed drainage is covered.