Prove it holds water before the tiles go down.
A flood test is the only objective proof that a waterproof membrane actually works. Visual inspection misses pinholes. Datasheets don't account for installer error. A 24-hour flood test, performed before any topping or tile bed is laid, is the standard of care required by AS 3740 and demanded by every careful builder and certifier.
The kit is simple but specific. Inflatable flood test balloons drop into the waste outlet and expand to seal the pipe under water pressure. Drain plugs in mechanical and pneumatic versions handle larger diameters and unusual outlets. A reliable hand pump, a measuring stick to verify water level isn't dropping, and a marker pen to log start and finish times round out the kit.
We stock the sizes that match Australian DWV plumbing — 40mm, 50mm, 80mm, 90mm and 100mm — plus the heavy-duty commercial sizes for podiums and roof drains. Every balloon is rated for repeated use and ships with a puncture-repair patch kit, because nothing kills a Friday afternoon faster than a deflating test plug at 4pm.
Order before the membrane goes down, not after the tiler arrives. A flood test is the cheapest insurance policy in the waterproofing trade.