Toilet supply line leaking or spraying — replace braided supply hose
Reported Symptom
Water leaking from the flexible supply line connecting toilet shut-off valve to tank. May be slow drip at fittings or sudden burst if hose failed.
Safety Warnings
- •A burst supply line in an unoccupied unit can flood multiple floors in minutes. Replace lines proactively on all toilets in aging buildings. Shut off water before any supply line work.
Possible Causes
- 1Braided supply hose aged and failed (plastic inner liner degrades)
- 2Fitting connections loose
- 3Corroded shut-off valve seat
- 4Hose installed over 10 years ago — standard lifespan exceeded
Tools Required
- Adjustable wrench
- Channel-lock pliers
- Bucket
- Towels
Parts Required
- 12-16 inch braided stainless steel toilet supply line (measure existing to match)
Diagnostic Steps
Locate shut-off valve at the wall behind the toilet. Turn clockwise to close. Flush toilet to drain tank.
Expected: Water supply stops; tank drains.
If fails: Shut-off valve won't close or leaks from valve itself = replace shut-off valve (requires water main shutoff).
Place bucket under supply line. Unscrew both fittings — one at the shut-off valve, one at the bottom of the toilet tank — by hand or with wrench.
Expected: Fittings unscrew smoothly; minimal water spills.
If fails: Fittings corroded or frozen = apply penetrating oil and wait, or use channel-locks carefully. Avoid cracking the valve nut.
Inspect old supply line — look for bulging, cracking, or corrosion at fittings. Note the length for replacement.
Expected: Measure length (common: 12" or 16"). Purchase braided stainless replacement.
If fails: If shut-off valve threads are damaged = replace valve.
Install new supply line: hand-tighten both fittings first, then snug with wrench — 1/4 turn past hand-tight. Do not overtighten.
Expected: No cross-threading; fittings snug.
If fails: Cross-threaded fitting = do not force. Unscrew and restart with straight alignment.
Open shut-off valve slowly. Check both ends of new supply line for leaks. Flush toilet and check again.
Expected: No leaks at either fitting after fill and flush.
If fails: Drip at fitting = shut off, snug fitting slightly more. Persistent drip = re-seat washer inside fitting.
Solution
Replace braided toilet supply lines every 8-10 years proactively — they are the #1 cause of bathroom floods in apartments. Use braided stainless steel only (never plastic or rubber).