Troubleshooting • Updated: 2025-12-15 • Reading time: ~8 min
Rental-first note: These guides focus on low-risk, reversible steps. If your lease forbids a modification (or the task involves gas/electrical/structural work), stop and contact maintenance.
Toilet keeps running: flapper vs fill valve (renter diagnosis)
A running toilet wastes water and can spike bills. In rentals, you can do a quick diagnosis and then decide whether it’s a simple adjustment or a maintenance request.
Renter approach: take a photo/video of the tank parts and the water level. It helps maintenance fix it faster.
Quick symptom table
| Symptom | Most likely cause | What you can do |
|---|---|---|
| Water slowly trickles into bowl | Flapper leak | Check chain slack, clean seat, report if worn |
| Tank refills randomly every few minutes | Flapper leak | Dye test; document and call maintenance |
| Continuous hissing | Fill valve issue | Adjust float level; report if it won’t stop |
| Water level too high (near overflow tube) | Float/adjustment | Lower float; stop if unsure |
Safe checks you can do
- Open the tank lid and look at the water level (it should be below the overflow tube top).
- Check the chain: it should have slight slack. Too tight can hold the flapper open.
- Do a dye test: add a few drops of food coloring to the tank; wait 10–15 minutes. If color shows in the bowl, the flapper is leaking.
- Adjust the float (if your lease allows simple adjustments): lower the water level slightly.
When to stop and call maintenance
- You can’t stop the running after a simple float adjustment.
- Parts look cracked, heavily corroded, or loose.
- The shutoff valve doesn’t work properly.
Related: Renter maintenance checklist • Slow drain guide