Toilet Won’t Flush? 5 Common Causes and How to Fix Them

If your toilet won’t flush, the problem is usually one of 5 things: a broken handle or chain, a faulty flapper, low tank water level, a clog, or a blocked vent pipe. Most of these you can diagnose in under 5 minutes by removing the tank lid and watching what happens when you press the handle.

This guide from Staggs Plumbing covers the common causes, what you can fix yourself, and when to call a licensed plumber for clogged toilets.

Quick Diagnostic Reference

1. Broken or Disconnected Handle and Chain

The flush handle connects to a lift chain inside the tank, which pulls up the flapper when you push the lever. If the handle feels loose or moves without resistance, the chain has likely disconnected or snapped.

DIY fix: Reconnect the chain to the handle lever or flapper. If the chain is broken, replacement chains cost a few dollars at any hardware store.

2. Flapper Won’t Open or Seal

The flapper is the rubber seal at the bottom of the tank that lifts to let water rush into the bowl during a flush. Over time, flappers warp, crack, or develop mineral buildup.

DIY fix: Flappers are universal for most toilets and cost under $10. Turn off the water supply valve, flush to empty the tank, unhook the old flapper, and snap on the new one.

3. Low Water Level in the Tank

Your toilet needs enough water in the tank to create the force that clears the bowl. The water should be about 1 inch below the top of the overflow tube.

4. Clogged Toilet or Drain Line

A clog is the most obvious cause when water rises in the bowl instead of flushing down. Use a flange plunger and create a seal over the drain opening.

5. Blocked Vent Pipe

Every drain system has a vent pipe that runs through the roof. When vents get blocked, toilets flush weakly or not at all.