
A shower pan leak test answers one question and answers it properly: does the pan hold water? The drain is plugged, the pan is filled, and the level is watched over hours. It is the only way to prove a pan rather than guess at it, and it is worth doing before anybody quotes you a bathroom.
A wet ceiling under a bathroom, or a damp patch on the wall outside the shower, has at least five plausible causes. The pan is one of them. Replacing a pan you did not need to replace is an expensive way to find that out.
| Cause | How it behaves |
|---|---|
| Failed pan or liner | Leaks whenever the shower is used, worsens over time |
| Grout and sealant failure | Same symptom — water gets behind the tile |
| The drain assembly | Leaks at the connection, not through the pan itself |
| Valve body inside the wall | Leaks even when nobody is showering |
| Supply lines in the wall | Constant, and usually worse than a pan leak |
| Splash past a poorly fitted door | Only with a specific person’s showering habits |
| Condensation on a cold line | Seasonal, and not a leak at all |
| Proves | Does not prove |
|---|---|
| Whether the pan and liner hold water | Whether the valve leaks |
| Whether the drain connection is sound | Whether supply lines in the wall leak |
| Whether water escapes at the pan-to-wall junction | Whether grout is failing above the flood line |
| That a wet ceiling below is or is not from the pan | What the repair will cost until we open it |
Which is why the test is a diagnostic rather than a whole answer. A pan that holds is genuinely useful information: it eliminates the most expensive suspect and turns the search toward the valve, the supply lines and the grout.
Set the test against the pan replacement figure and it makes its own argument. A few hundred dollars to establish whether the four-figure job is the right one is not a close call, and any contractor who wants to replace a pan without testing it first is asking you to fund a guess.
Everything we price is on the pricing page.
The timing pattern is the strongest single clue. Wet after use and dry in between points at the pan, the drain or the grout. Wet all the time points at a supply line or the valve body, and that is a different search entirely.
A pan is not one thing. It is a waterproof layer, a drain connection and a tiled surface sitting on top of both, and each of the three fails differently.
None of the three is repairable in place. That is the uncomfortable fact behind the price of a pan replacement, and it is why proving the pan has actually failed is worth the cost of the test.
We are licensed and insured plumbers, and this site is about leaks — finding the ones you cannot see and repairing them properly. Roughly half of what looks like a plumbing leak turns out not to be one, so the boundary is worth stating plainly.
Roof leaks are a roofer. Water under an air handler is an HVAC technician clearing a condensate drain. Water under an appliance is appliance repair. Drying, restoration and mold are separate trades again, and gas line repair is SoCalGas or a licensed gas fitter. We detect gas leaks, we do not repair gas lines.
The full list, with the trade to call for each, is on what we don’t do.
Four things that make the visit shorter and the result cleaner.
Allow half a day. A flood test cannot be rushed without ruining it, and a test that runs for twenty minutes proves nothing at all.
Then the conversation moves to repair, and the honest headline is that the plumbing is the smaller half of it.
| Part of the job | Roughly |
|---|---|
| Removing tile and the failed pan | Unavoidable, a liner cannot be repaired in place |
| New pan and waterproofing | The part we are actually specialists in |
| New tile and grout | Usually the largest single line on the invoice |
| Replacing the valve while it is open | $225 – $575, and worth doing then |
| Repairing damage below | Depends entirely on how long it ran |
The full picture is on shower pan leak repair. The reason to test before committing to any of it is that this list is what you avoid if the pan is sound.

Prove whether the pan holds before anyone quotes you a bathroom.
(714) 386-7923Call or text, day or nightSchedule a VisitThe drain is plugged, the pan is filled to just below the threshold, the level is marked, and it is watched for several hours while the space below is monitored. If the level drops and moisture appears below, the pan is failing. If it holds, it is not.
Allow half a day. A failing pan usually shows within the first hour or two, but a test cut short proves nothing: a slow liner failure can take longer to register below, and that is exactly the case worth catching.
It sits in the standard $150 to $500 detection band, credited toward the repair. Against a $2,000 to $6,000 pan replacement, testing first is not a close call.
Likely the pan, the drain connection or the grout — all three only leak while water is running on them. Wet all the time points somewhere else entirely, usually the valve body or a supply line inside the wall.
You can plug a drain and fill a pan. What is harder is reading the result: distinguishing evaporation from a slow loss, taking moisture readings below, and knowing which of the other five causes to check when the pan holds.
Not when it is done with a proper test plug and removed properly. Forcing an inflatable plug into an old cast drain is how they get damaged, which is a reason to be careful rather than a reason not to test.
Most often the valve body inside the wall, a supply line, failed grout above the flood line, or the drain connection. That is what the rest of the visit is for — the test eliminates the expensive suspect and narrows the search.
For at least a day before the test, yes — a dry starting point is what makes the result readable. Whether you should stop using it after depends on what we find, and we will tell you plainly.
Read your policy. Most treat sudden damage more favourably than deterioration, and a pan liner that has slowly failed over years is often argued as the latter. Photographs and a dated written report are what the argument rests on either way.
No — a pan replacement means removing tile, and that is a scheduled job with a quote, not an afternoon. What you get on the day is the result, photographs and a written quote for the work.