Ceiling stains and shower pans
Bathroom Leak Repair Denver
Ceiling Stains, Shower Pans & Supply Leaks
The stain on the ceiling below your bathroom is telling you something specific, and most people paint over it before they read it. Timing, shape, and location narrow five possible causes down to one before anybody cuts drywall.
- Timing tells you the source
- Supply drips, drains only run
- Pan failures versus grout failures
- Tests you can run today
Read the stain before you open the ceiling
Timing is the first clue and it's nearly diagnostic. A supply line is pressurized every minute of every day, so a supply leak makes a stain that grows steadily and stays damp overnight. Drain-side leaks only leak while water is moving, so that stain darkens after a shower and dries between uses. And a stain that appears exclusively when someone fills the tub high and leans back is the waste-and-overflow gasket behind the tub, almost every time.
Shape and location matter next, with one catch that fools people constantly: the stain marks where water fell off the framing, not where it left the plumbing. Water runs along the top of a joist or the underside of subfloor until it hits a nail, a seam, or a low spot, and then it drops. In the 1920s bungalow belt and the older blocks of Littleton, where a second bath often sits over a kitchen, the actual failure is regularly four or five feet from the ring on the ceiling.
One more thing worth internalizing before you spend money. The most common source of water inside a bathroom wall isn't a pipe at all. It's failed caulk at the tub deck, an open grout line in a shower corner, or a shower door track that funnels water into the wrong side of the curb. Tile is not waterproofing. It's a wear surface over waterproofing, and the waterproofing is what fails.
The five usual suspects
Most bathroom leaks are one of five things, and you can rule several of them in or out with an afternoon and no tools. The point of the tests below is to make water appear on your schedule rather than waiting for it, because a leak you can reproduce is a leak somebody can fix on the first visit.
Work through them in that order, top down, and write down what happens. Every one of these tests is free, reversible, and safe for anyone to run, and each suspect you eliminate saves an hour of somebody's diagnostic time and a hole in your ceiling. A note that reads "wet after showers, dry after baths, nothing overnight" tells a plumber more in one line than a long conversation at the door.
- Surface water: dry the walls completely, then run only the shower head for ten minutes without touching anything else. Wet ceiling after? Water is getting past the tile or the door.
- Shower pan or liner: plug the drain, fill the pan an inch deep, mark the water line, and leave it two hours. A drop in level with a fresh stain below is a pan failure, not a plumbing repair.
- Toilet seal: feel for rocking, then look for a spongy floor at the front of the bowl. A stain that blooms right after a flush is a wax ring or a broken closet flange.
- Tub overflow: fill above the overflow plate and let it sit. Leaks that only show up during baths, never showers, live in that gasket.
- Supply side: check the angle stops and braided lines under the sink and behind the toilet with a dry paper towel. Any moisture at a packing nut is real.
| Source | When the stain grows | Usual tell |
|---|---|---|
| Grout, caulk, or door track | After showers only | Loose tile, dark grout line, wet curb ends |
| Shower pan or liner | After long showers | Damp joist directly under the pan corner |
| Wax ring or closet flange | Right after a flush | Toilet rocks, floor soft at the front of the bowl |
| Waste and overflow gasket | Only during baths | Nothing at all when you shower |
| Supply line or valve body | Constantly, day and night | Stain never fully dries out |
What chasing a bathroom leak actually costs
Access decides the bill, not the part. A wax ring reset is a small job and commonly lands in the low hundreds along the Front Range, and it doubles when the closet flange under it has broken and needs a repair ring or a replacement. Angle stops and braided supply lines are cheaper still. A shower valve or a leaking drain arm reached through an access panel behind the wall is a few hundred; the same repair reached by removing tile costs whatever the tile costs to put back.
Shower pan replacement is the one that surprises people, because it isn't a plumbing repair. It's a demolition and a rebuild: tile out, pan out, new liner or a modern bonded system, new drain assembly, new tile. That work runs into the thousands and climbs with the size of the shower and the taste of the tile. And it's the reason a failing pan in a 1990s bathroom usually turns into a remodel conversation. If you're rebuilding the shower anyway, rebuilding it once is the cheaper year.
Two honest notes. Plumbers find and fix the leak; drywall, texture, paint, and tile are typically a separate trade and a separate invoice, so ask upfront who closes the hole. And resist the urge to re-caulk over a known wet wall. Fifteen dollars of silicone is worth trying when the evidence points at surface water and the substrate is still sound, but sealing a wall that's already saturated just traps the water where you can't see it.
Damp overnight means supply, and supply gets handled now. Damp only after use means drain or pan, and that can wait for a scheduled visit as long as you stop using the fixture. Anything soaking a ceiling with light fixtures in it stops being a plumbing question and becomes an electrical one.
Need this handled this week?
Start a quoteStop using it, then dry it, then rebuild
Take the fixture out of service the day you find the stain. That's easy with a second bathroom and a genuine hardship without one, which is exactly why single-bath houses get leaks that run for months. A shower you keep using is a shower that keeps feeding the framing under it.
Water and light fixtures do not mix, and a bathroom leak lands on top of can lights and bath fans more often than anywhere else in a house. Kill that circuit at the breaker before you poke at a wet ceiling. A ceiling holding water sags first and then lets go all at once, so keep people and pets out from underneath it, and if it's bulging, open a small drain hole at the low point with a bucket under it rather than waiting.
Drying comes before rebuilding, always. Pull wet insulation instead of hoping it dries in the cavity, check the subfloor edges for delamination, and give it air for several days. Then do the maintenance that prevents the sequel: fresh caulk at the tub deck every few years, and an eye on cartridges, which wear faster in the hard groundwater around Firestone and Commerce City than in Denver's soft snowmelt. If the bathroom in question sits on a concrete slab rather than over a basement, the diagnosis changes completely, and our slab leak page covers that version.
Related work
More emergency services
Burst Pipe Repair
split copper and PEX, shutoff sequence, temporary containment, permanent fix
→Water Main & Service Line Repair
the buried service line from meter to house, leaks in the yard, replacement
→Slab Leak Detection
warm spots, unexplained bills, acoustic and thermal location, reroute vs. break-in
→Sump Pump Repair
failed floats, discharge freeze, battery backup, spring melt loading
→Gas Line Repair
smell-gas protocol, appliance lines, sediment traps, when to evacuate first
→Where we cover
Front Range cities we write for
Questions we actually get
Bathroom Leak Repair: quick answers
The ceiling stain is dry now. Do I still need to fix it?
Yes, because dry means the leak is intermittent, not gone. Intermittent points at drain-side or surface water, and both keep soaking framing every time the shower runs. Note whether the stain has grown by marking its edge in pencil with today's date. A stain that expands over two weeks is an active leak regardless of how dry it feels.
Can a shower leak without any visible damage to the tile?
Routinely. Tile and grout are porous by design and the waterproof layer sits behind them, so a failed liner, an unsealed corner, or a clogged weep hole in the drain lets water bypass a shower that looks perfect. That's why the fill test on the pan matters. It tests the layer you can't see instead of the one you can.
Is a bathroom leak an after-hours emergency?
Usually not. Shut the fixture down, put a bucket under the drip, and book a normal appointment. It becomes an emergency when water reaches electrical, when a ceiling starts to bulge or sag, when a supply line is spraying rather than dripping, or when you can't stop the water at a local shutoff and have to close the main.
Stain under the bathroom?
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