What the Water Pressure Test Really Asks For

Before a water pipe is buried or covered, AS/NZS 3500.1:2025 requires it to be flushed until clear, then hydrostatically tested at 1500 kPa for at least 30 minutes, with no leakage. Tanks are filled to overflow and held for at least one minute. Some utilities test fire services at a higher pressure or for longer, so check the authority's requirements for that work.

01The clauses that set the test

Section 18 of the standard sets three steps. Each one has its own clause:

• Clause 18.2: flushing before the test.
• Clause 18.3.1: hydrostatic test at 1500 kPa for not less than 30 minutes, with no leakage.
• Clause 18.3.2: tank overflow for not less than one minute.

02Two common mistakes

• Testing at working pressure. The code's test is 1500 kPa, not the working pressure.
• Covering the pipe before the test. The test has to happen first, so leave joints exposed where the system allows it (clause 18.3.1, elastomeric seals).

If you want a second check on a test plan before a job starts, call the office on 02 8111 6644.