After hearing a drip-like, almost electrical buzz from behind a bathtub wall, a homeowner paid for a wall opening and camera check — and still came away without an identified leak.
Redditors, however, said the answer might be in the shower fixtures rather than inside the wall.
Here's what to know
In a Reddit thread in r/Plumbing, the homeowner said the 16-month-old tub had begun showing isolated patches of moisture along the rim. The tub had gone unused for 24 hours, a dehumidifier had already been running, and even after a plumber opened the wall, no definite source of the water was found.
(Click here if the embedded video does not appear.)
"We had a plumber come out and after the hole was cut, he saw no water staining within the walls and we have no water dripping onto the floor," the OP said. "I'm at a loss."
From there, much of the discussion shifted to parts hidden by the shower trim.
TCD Picks » Quince Spotlight
💡These best-sellers from Quince deliver affordable, sustainable luxury for all
Suggestions included a leaking drop-ear elbow near the shower head, a problem at the valve behind the trim plate, or an issue with the overflow gasket — all spots where water can move before it appears somewhere else.
More background
That kind of mystery is what makes bathroom leaks so costly for homeowners. Water rarely drips straight down in a visible line. It can move behind tile, run along framing, or collect at low points before appearing several inches — or even stud bays — away from the actual problem.
One user offered an explanation for the odd sound: "The humming or electrical-sounding noise in a wall near a water line is often a supply pipe vibrating."
The same commenter added that "if the tub overflow plate gasket is not fully seated, it can slowly wick moisture and it shows up on the rim."
The cost is not just the water itself. It is the diagnostic labor, drywall cuts, and follow-up repairs that can add up when the first inspection misses the source. Even a targeted fix behind a trim plate could save someone from a much larger bill if it prevents moisture damage from spreading into tile, wallboard, or framing.
The tub was only 16 months old. Even newer installations can hide workmanship problems that may be better handled by the original installer than by repeated exploratory visits.
What can be done?
Before opening anything else, users recommended starting with the simplest checks: dry the area around the tub spout, shine a light across the tile to catch any fresh drips, and remove the handle and trim plate to inspect behind them.
They also pointed to the overflow plate gasket as something to inspect and suggested isolating other shower parts one at a time.
One user asked, "What happens when you shut the water off and take the shower head and little stem pipe off?"
That kind of step-by-step troubleshooting can help narrow down the problem before anyone opens another wall, potentially saving on extra diagnostic labor and cosmetic patching if the leak is accessible from the shower side.
If the leak does trace back to the original installation, documenting where moisture appears and what tests were done can make it easier to press for a callback or a warranty-related repair.
Where can I learn more?
These stories cover the kinds of hidden plumbing problems that can turn a small bathroom mystery into an expensive repair. They include simple leak-detection tricks, toilet tests, and routine checks that can catch water issues before damage spreads.
• Across U.S. homes, a simple leak check has caught hidden plumbing problems early.
• A home inspector showed that drops of coloring can expose a slow toilet leak.
• When a toilet starts seeping, a quick DIY fix can stop wasted water.
• In many bathrooms, food-coloring tank tests reveal silent leaks running unnoticed.
Get TCD's free newsletters for easy tips, smart advice, and a chance to earn $5,000 toward home upgrades. To see more stories like this one, change your Google preferences here.
