A flood test costs a drain plug and a night of patience. Skipping it risks a full demo under warranty. Every waterproofing manufacturer, inspector and veteran installer lands on the same side of that trade, so here is how to run the test properly.
When to Test: After Sealing, Before Tile
Test once the pan, drain connection and seam waterproofing are complete and cured per the sealant manufacturer's guidance, and before a single tile goes down. Tile hides evidence; the test only means something on the bare membrane. If you are mid-build, see installing a pre-sloped pan for where this step lands in the sequence.
How to Run the Test
- Seal the drain with a proper test plug at the flange level, not a rag and a prayer
- Fill the pan with water to just below the curb or the threshold line
- Mark the water line precisely: painter's tape and a pencil line work
- Let it stand, commonly for 24 hours or per your local code's required duration
- Check the mark, then check below: ceilings and framing tell on slow leaks
Reading the Result
Level holds: photograph the marked line with a timestamp for your job file, drain the pan, and tile with confidence. That photo is warranty gold.
Level drops: confirm the plug seated first, since a leaking test plug is the classic false alarm. Then inspect the drain flange seal and every seam and corner. Fix, recure, retest. Never negotiate with a failed flood test.
Make It Part of the Quote
Write the flood test into your scope as a named line item. Clients read it as professionalism, inspectors expect it, and it protects the margin on the entire shower system install. Sealants, plugs and banding live in the waterproofing collection.
Flood Test FAQ
How long should a shower pan flood test run?
Follow your local code; a common practice is a 24-hour standing test. Longer never hurts the result, only the schedule.
Do foam pan systems really need a flood test?
Yes. The pan is factory-waterproof; the test is proving your drain connection and your seam work, which are field-built every time.
What water level is right for the test?
Fill to just below the lowest containment point, usually the curb top or threshold, so the test covers every seam the shower will ever see in service.
The job pays twice. Contractors earn points on every waterproofing order through the PlaceForPros Contractors Program.