A toilet that won't flush properly is one of the most frustrating household problems. Before you call a plumber, here are eight common causes and what you can do about each one.
1. The Water Level Is Too Low
Open the tank lid and check the water level. It should be about one inch below the top of the overflow tube. If it's lower, adjust the float valve or fill valve to allow more water into the tank.
2. The Flapper Is Worn or Warped
The flapper is the rubber seal at the bottom of the tank. Over time, it deteriorates and doesn't seal properly, causing water to slowly leak from the tank into the bowl. Flappers cost $5-10 and take five minutes to replace.
3. There's a Clog in the Trap
The most common cause of a toilet that won't flush is a clog in the built-in trap (the S-shaped channel inside the toilet). A plunger with a flange (the kind with a fold-out rubber cup) is the most effective tool. Push and pull firmly for 15-20 seconds.
4. The Drain Line Is Partially Blocked
If multiple fixtures are draining slowly, the problem is downstream in the drain line, not in the toilet itself. This typically requires a drain snake or professional cleaning.
5. The Lift Chain Is Too Loose or Tight
The lift chain connects the flush handle to the flapper. If it's too loose, the flapper won't lift enough for a full flush. If it's too tight, the flapper won't seal. Adjust so there's about half an inch of slack.
6. Rim Jets Are Clogged
The small holes under the rim of the bowl distribute water during a flush. In areas with hard water, these can clog with mineral deposits. Clean them with a small wire or brush and white vinegar.
7. The Vent Pipe Is Blocked
Every plumbing fixture has a vent pipe that allows air into the drain system. If the vent is blocked (by leaves, bird nests, etc.), the toilet may flush slowly or gurgle. This typically requires professional service.
8. The Sewer Line Has a Problem
If you're experiencing slow flushing throughout the house, sewage odors, or gurgling sounds from multiple drains, the issue is likely in the main sewer line. This requires a professional camera inspection to diagnose.
Tried these fixes and still having problems? Call 562-219-4085 — our licensed plumbers can diagnose and fix any toilet issue.