THE SHORT ANSWER
Water on the floor outside a tub or shower may come through the opening, under a door, around a threshold or wall jamb, over the tub rim, or from a drain or concealed plumbing path. Do not start by covering every joint with caulk. Dry the area, run one small observation at a time, and follow the first wet point so the correct product instructions or professional can address the actual path.
Before you try anything
Stop using the tub or shower if water is near an outlet, switch, heated floor control, light, fan control, cord, or other electrical equipment; do not touch wet electrical devices or stand in water to reach them. Keep clear of cracked, chipped, loose, scraping, or misaligned glass. Stop for a rapidly spreading leak, soft flooring, a sagging ceiling below, sewage odor, contaminated water, or a mobility and slip risk. Renters should report the moisture problem promptly to the landlord or building manager.
Before you begin
This guide covers a small amount of clean water that appears during ordinary tub or shower use when the enclosure, floor, and glass look stable. It is for floor-level observation only. It does not cover sewage, a major overflow, cracked or loose glass, water near electrical equipment, a soft or swollen floor, water entering a lower room, opening walls, removing doors, cutting sealant, drain disassembly, or plumbing repair.
Dry towels; paper towels; a small pitcher; removable painter's tape placed only on dry, sound trim or floor; a flashlight; the enclosure brand and model if visible; and a phone for photos. Use a second person to operate the water while the observer remains on a dry floor outside the splash path.
In a rental, report the problem to your landlord or property manager before making repairs. Building rules and local requirements vary.
Work through the checks
- 01
Reset and map the evidence
Dry the tub rim, threshold, door edges, wall jambs, nearby baseboard, and floor. Photograph any swelling, staining, failed finish, or mold before cleaning. Place separate paper-towel markers outside each likely path so one wet marker does not spread water to the others.
- 02
Check for a no-use leak
Wait with all fixtures off. Water that returns without using the tub or shower suggests a supply, valve, concealed plumbing, condensation, or another source rather than ordinary splash. Stop testing and arrange inspection.
- 03
Test the drain without spraying the enclosure
Pour a small pitcher of clean water directly into the drain without wetting the walls, door, curtain, overflow opening, or tub rim. If water appears outside or below, stop; the drain or concealed path needs a plumber or building professional.
- 04
Observe the opening with low, directed spray
Only when the floor is dry and safe, run a low flow directed at the back wall and away from the opening for a few seconds. Watch the curtain edge, door overlap, bottom seal, threshold, corners, and wall jambs from the dry side. Stop at the first wet marker.
- 05
Check the normal curtain or door position
For a curtain, keep its lower edge fully inside the tub and its ends against the wet-side walls. For a sliding enclosure, use the panel orientation specified by the manufacturer; one cited Sterling guide places the inside panel closest to the showerhead. Do not assume that rule fits every door.
- 06
Compare spray direction and user position
If the low directed test stays dry, repeat one brief normal-use pattern without blocking the drain. Note whether spray strikes the opening, a bather's movement pushes the curtain outward, or water runs along the rim to a corner. Do not continue after a repeatable path appears.
- 07
Inspect the dry joint and surrounding material
After the area dries, photograph gaps, separated sealant, missing seals, loose trim, or dark and soft material without probing it. Find the exact enclosure instructions or call qualified service before adjusting glass or applying sealant.
What your result means
These observations help choose a next step. They do not confirm a diagnosis.
| What you notice | What it tells you | Next step |
|---|---|---|
| The drain-only pour produces water outside or below | A drain, overflow, trap, connection, or concealed path may be leaking | Stop using the fixture and contact a plumber, landlord, or building professional. Do not open the drain or ceiling. |
| Water crosses only at the curtain or open door edge | Curtain position, door closure, spray direction, or user movement may be carrying water out | Correct the normal-use position and retest briefly. Replace a damaged curtain or seal only with the correct product part or instructions. |
| The first wet point is under the door or threshold | A bottom seal, door alignment, threshold joint, or product-specific installation detail may be involved | Use the exact enclosure manual or qualified installer. Do not remove or adjust tempered-glass panels as a general DIY step. |
| The first wet point is at a wall jamb or corner | Water may be following a jamb, failed sealant joint, rim, or wall-surface defect | Stop repeated wetting, dry the area, and use the manufacturer sealing instructions or a qualified bath installer. |
| Paper markers stay dry but the floor or room below becomes damp | Water may be traveling inside the wall, under the base, through the floor, or from another plumbing source | Stop use and arrange professional moisture and plumbing inspection before cosmetic repair. |
Know what happens next
Check the outcome
After the correct repair or positioning change, dry the full area and repeat only the smallest test that previously reproduced the leak. The threshold, jambs, opening, tub rim, floor edge, baseboard, and room below should remain dry during the test and after normal use. Continue monitoring through several uses because a dry surface test cannot rule out a concealed moisture path.
When to call a professional
Stop and get professional help for wet electrical equipment, cracked or loose glass, a door that scrapes or may leave its track, rapid or uncontrolled water, soft or swollen flooring, water below the room, recurring mold or musty odor, sewage, or a leak that appears with fixtures off. Contact the landlord promptly if you rent. Do not caulk over wet or moldy material or use cosmetic sealant to hide an unknown source.
Take useful notes with you
A short record makes it easier to explain the problem to a landlord, technician, or responder. Do not collect notes during an emergency.
Notes stay in this page until you leave or reload. Download a copy to keep them. They are not sent to us.
Common questions
Should I recaulk every edge first?
No. Water may be crossing the opening, coming through a drain path, or traveling behind the enclosure. Identify the first wet point and use the exact product instructions; EPA also advises against caulking over moldy surfaces.
Which sliding door panel should be closest to the showerhead?
It depends on the enclosure. The cited Sterling guide specifies the inside panel for that product family, but another model may differ. Check the label and manual before treating panel order as a universal rule.
Why test the drain with a pitcher?
A small drain-only pour keeps spray off the enclosure. If water still appears outside or below, the evidence points away from ordinary splash and toward a drain or concealed path.
Can I adjust the rollers or remove the door myself?
This guide does not recommend it. Tempered-glass doors are heavy and product-specific; use the manufacturer's procedure with qualified help or call an installer.
Sources & scope
This is a desk-researched guide, not a hands-on test or an on-site diagnosis. A licensed tradesperson has not independently reviewed this edition. Follow your product’s manual and local requirements.
- Sterling by Kohler Installation Guide 1370893-2-B
Supports distinct water paths at the threshold, door-panel gap, overlapping panels, wall jamb, spray direction, and sealant locations for that product family; it also shows why exact model instructions matter.
- U.S. EPA — A Brief Guide to Mold, Moisture and Your Home
Supports fixing the water source, drying wet materials within 24 to 48 hours, promptly reporting rental moisture problems, and not painting or caulking moldy surfaces.
- Electrical Safety Foundation International — Water-Damaged Electrical Equipment
Supports treating water-exposed electrical equipment as a continuing shock and fire risk and having qualified electricians evaluate it before power is restored.
Published 2026-09-30 · Our editorial policy · Report a correction