How to Prove Your Shower Pan Didn't Leak: The Water Test That Protects Tile Contractors From Liability
The 'water downstairs' call is coming. Here's how to water test every shower pan and document it so you're never blamed for a leak you didn't cause.
The phone rings at 10pm on a Sunday. It's the homeowner from that master bath you finished four months ago. "Water is coming through the ceiling downstairs. I need you here first thing tomorrow."
Your stomach drops. You drive over at 7am convinced you made a mistake. Forgot a corner on the waterproofing. Punctured the membrane with a screw. Something. Anything.
You get there, you pull the drain cover, and you find what every tile installer eventually finds: a drain packed solid with hair and debris. The pan didn't leak. The drain clogged, water rose past the top of your waterproofing, and spilled down the outside of the curb into the subfloor.
Your work is fine. Now you have to prove it.
This is the article I wish someone had handed me after my first "water downstairs" call. It covers the shower pan water test, but more importantly, it covers how to document the test so you have proof when a leak call comes in. Every contractor gets this call eventually. The ones who water test every pan and save the photos walk away with their reputation and wallet intact. The ones who don't, pay for someone else's clogged drain.
Why Contractor Liability on Shower Leaks Is a Bigger Deal Than Most Installers Realize
Here's what happens when a homeowner reports water damage below a bathroom they just remodeled:
- Insurance adjuster shows up
- Adjuster sees new tile work
- Adjuster calls "the tile guy" (you) and says the leak is from your installation
- Homeowner agrees because they don't know any better
- Your insurance carrier gets involved, your rates go up
- Even if you eventually prove it wasn't your work, you've lost time, money, and sleep
Most leaks in a recently tiled shower are NOT from the tile work. The actual common causes:
- Clogged drain — the #1 cause. Hair, construction debris, soap scum.
- Shower door/glass installation after your work — punctured membrane, failed seal.
- Plumber damaging the liner during rough-in or finish work.
- Homeowner drilling into walls to hang a caddy or shelf.
- Grout line failure from shifting — cosmetic, not structural, but blamed on waterproofing.
But the burden of proof falls on you. If you can't prove the pan was watertight when you finished, the default assumption is that you caused the problem. Water testing with documentation flips that. And if you've thought carefully about how you price shower work, water testing is the step that protects every dollar of margin you built into that estimate.
The Water Test: What It Actually Is
A shower pan water test (also called a flood test) is exactly what it sounds like: you plug the drain, fill the pan with water, mark the water line, and check it 24 hours later to confirm the water level didn't drop. If it holds, your waterproofing is watertight.
The test has been industry standard for decades. The Tile Council of North America (TCNA) recommends it. The International Plumbing Code and Uniform Plumbing Code reference it. Minnesota Plumbing Code 408.7.1 now requires it on new construction. Many other jurisdictions are moving in the same direction.
But most residential installers don't do it. Why? Because it takes 24 hours, clients don't want to wait, and "I've never had a leak" feels like a good enough track record. Until the phone call.
When to Perform the Water Test
The test is done after the waterproofing is complete and cured, but before any tile is installed.
This timing is critical. If you find a leak after tile is installed, the fix requires demolishing the tile. If you find a leak before tile, you patch the membrane in 15 minutes and re-test.
Cure time depends on the product:
- Liquid membranes (RedGard, Hydroban, AquaDefense): 24–72 hours depending on humidity and temperature. Laticrete's Hydroban can be flood-tested in 2 hours at 70°F and 50% humidity, 24 hours in cooler conditions. Read the TDS for your specific product.
- Sheet membranes (Kerdi, Wedi): Flood-test immediately. No cure time required. Schluter specifically recommends a 24-hour flood test on all Kerdi showers.
- Traditional PVC liner + dry pack: The PVC liner can be tested before the mud bed goes in (the "pre-slope flood test"). Then some codes require a second test after the top mud bed and before tile.
What You Need to Perform a Water Test
Equipment list:
Test plug (fits your drain size — usually 2 inch). Two options:
- Mechanical plug (wing nut style): $10–15 at any supply house. Can loosen over 24 hours and give a false leak reading. Make sure it's tight.
- Pneumatic/inflatable plug: $25–40. Easier to install, harder to get wrong. Worth the extra cost. Get the kind with an extension hose to reach the drain assembly cleanly.
Water source. Use a garden hose from an outside spigot, NOT the shower head you just installed. You need to isolate the pan from the plumbing to prove the leak (if there is one) is in your membrane, not in the plumber's rough-in.
Measuring reference. A piece of painter's tape or pencil to mark the water line. The tape is fine.
Camera. Your phone. You'll take a lot of photos.
Step-by-Step Water Test Procedure
Step 1: Confirm membrane cure. Check your product's technical data sheet. Don't start the test before the membrane is fully cured.
Step 2: Plug the drain. Install your test plug. For pneumatic plugs, inflate to the pressure specified on the plug. For mechanical plugs, tighten until the wing nut won't turn by hand. Take a photo of the plugged drain.
Step 3: Fill with water. Fill the pan to within 1 inch of the top of the curb's waterproofing (not the top of the finished stone). Use an external water source — garden hose from outside. Never use the shower plumbing. Take a photo of the filled pan.
Step 4: Mark the water line. Press a piece of painter's tape onto the curb or wall exactly at the water line. Take a close-up photo showing the tape at the water surface with a ruler or measuring reference if possible.
Step 5: Timestamp everything. Take a wide photo of the plugged, filled pan. Make sure your phone has location and timestamp enabled so the metadata proves when and where the test was done. Better: write the date and time on a piece of paper and include it in the photo.
Step 6: Wait 24 hours. Industry standard minimum. Some installers go 48 hours for extra confidence. If your customer is pushing the schedule, 24 is acceptable per TCNA.
Step 7: Check and document. Return at the 24-hour mark. Check if the water level has dropped below your painter's tape line. Take another timestamped photo of the water level against the tape.
- No drop = test passed. Your pan is watertight.
- Any measurable drop = test failed. Find the leak before continuing.
Step 8: Drain and proceed. If the test passed, remove the plug, let the water drain out, and start tile installation. Save every photo in the job's folder.
The Photo Protocol (This Is What Saves You)
Here's what to photograph on every single shower pan water test. These are the photos that end "water downstairs" conversations the moment you pull them up on your phone.
Before water fill:
- Wide shot of the dry shower pan with the drain plugged — whole pan, plug, walls, and curb visible.
- Close-up of the test plug installed and tightened.
- Photo of the membrane product container in the same frame as the shower — proves what product you used.
During fill:
- The water source (garden hose) running into the pan — proves you used an external source, not the shower plumbing.
- Wide shot of the pan full of water to the intended line.
- Close-up of the water line marked with painter's tape.
The timestamp proof shot:
- A photo that includes the filled pan AND a newspaper or a piece of paper with today's date written on it. Old-school but foolproof. Alternatively: a photo of the pan with your phone's digital clock visible in the frame showing date and time.
24 hours later:
- Wide shot at the 24-hour mark showing the water level still against your tape line.
- Close-up of the water line vs. the tape — proof that the water didn't drop.
- Another dated reference (newspaper, handwritten date, clock in frame).
After draining:
- Photo of the drained pan, plug removed, ready for tile.
Save all of these in a folder named after the job address. Keep them for at least 5 years.
What Happens When You Get the "Water Downstairs" Call
Four months go by. Your job is done, you've been paid, you're on the next one. Sunday night, 9:47pm, the call comes.
The conversation that should happen:
Homeowner: "There's water coming through the ceiling below the shower you built. You need to fix this."
You: "I understand you're stressed, and I'll come look at it first thing tomorrow. Before I do, I want you to know I water-tested your shower pan for 24 hours before tiling. I have timestamped photos and a record of the test. The pan was watertight when I finished. When I come out, we'll identify the actual source of the leak together."
Homeowner: (surprised) "Oh. Okay."
The tone shifts the moment you mention photos and documentation. You're no longer defending your work — you're helping them find the real problem.
When you show up:
- Check the drain first. 80% of the time, it's clogged. Pull the drain cover, check for hair or debris. Take a photo if you find it.
- Run water in the shower and look for where it actually leaks. Often it's the shower door seal, a failed grout line on a wall, or plumbing — not the pan.
- Show the homeowner your water test photos. Pull them up on your phone. Walk them through what they show.
- Explain the curb waterproofing line — see the section below.
If the leak IS from your work, you handle it. That's the trade. But 90%+ of "water downstairs" calls aren't from the tile installation.
The Curb Waterproofing Line: The Conversation to Have at Walkthrough
On a custom shower with a stone-top curb, the waterproofing ends at the top of the cement board or backer — below the finished stone. The stone cap sits above the waterproof line. If water in the shower pan rises above that line (because the drain is clogged or water is pooling from a glass enclosure issue), it passes over the waterproofing and runs down the outside of the curb into the subfloor.
Most homeowners assume the waterproofing goes all the way to the top of the visible surface. It doesn't.
At your final walkthrough, point at the curb and say:
"Here's something important. The waterproofing on this curb ends at this height — below the stone top. If your drain ever clogs and water backs up above this line, it will flood downstairs. Keep your drain clear. Don't let hair build up."
30 seconds of conversation. Saves you hours of callback investigation.
Why the 24-Hour Test Matters Even on "Easy" Showers
Some installers skip the water test on prefabricated pan systems like Schluter Kerdi or Wedi because "they're engineered systems — they can't leak."
Schluter themselves recommend a 24-hour flood test on all Kerdi installations. So does Wedi. Here's why it matters even on prefab:
- Seams and corners. Even prefab systems have seams — Kerdi-Band over a seam, Kerdi-Kereck at corners, drain assembly integration. Any of these can fail if not installed perfectly.
- Drain installation. The weakest point in any shower pan is the drain assembly. The connection between the membrane and the drain flange is where most leaks happen. Water testing catches this.
- Puncture damage from adjacent trades. The plumber, electrician, or GC can damage your membrane between the time you install it and the time you come back to tile. Testing immediately before tile confirms the membrane is intact at the moment of tile setting.
- Warranty coverage. Schluter, Laticrete, and most membrane manufacturers may void their warranty if a leak occurs and you didn't perform the recommended flood test. Make sure you've also thought through how much thinset you need for the installation that follows — using the wrong product or quantity can compound liability issues.
Including the water test as a standard line item in your tile estimate process is the simplest way to make sure it never gets skipped.
How Long to Keep Water Test Photos
My rule: 5 years minimum. Storage is basically free. The cost of not having them when you need them is enormous.
Organize photos by job address in a cloud storage system — Google Drive, Dropbox, or the photo gallery built into your estimating software. Don't just rely on your phone's camera roll. If you lose the phone, you lose the evidence.
What NOT to Do
Don't skip the test on "small" showers. A guest bath flood downstairs is just as expensive as a master bath flood.
Don't accept the homeowner's rush. "We need you to start tile tomorrow" is not a reason to skip a 24-hour test. The test saves them money long-term. Explain this calmly and stick to your standards.
Don't test after tile is installed. If you find a leak then, the fix is demolition. Always test before tile.
Don't test with the shower plumbing. Use an external water source. If you fill from the showerhead and find water on the ground, you can't tell if the pan leaked or the plumbing did. Isolate the variables.
Don't delete old photos. Your job photos are your legal protection. Keep them.
Don't flood-test without checking membrane cure time. Premature testing can cause false failures or damage unreacted membrane.
Automate the Documentation
Every water test produces 10–15 photos plus a note about the test timing and result. Over 50 jobs, that's 500+ photos scattered across your phone in no particular order.
This is exactly why TileForeman has a dedicated water test photo category in the job record. You tag photos at the time of the test, the app attaches them to the job file with timestamps, and the whole record is searchable years later. When the "water downstairs" call comes, you pull up the job by address and see every test photo in order. Free during beta if you want to check it out.
Wrapping Up
The shower pan water test is 24 hours of patience and 15 minutes of photos. It saves you from "water downstairs" phone calls that could cost you thousands of dollars, damaged relationships, and stress you can't put a price on.
Test every pan. Document with photos. Explain the curb waterproofing line at walkthrough. Keep records for 5 years minimum.
When the call eventually comes — and it will — you'll be the installer who pulls up timestamped photos within 30 seconds and walks away with your reputation intact.
Tomasz K. — Tile installer, 13 years in the trade