Search guides

Fix a toilet that will not flush

We'll confirm the symptom, check the handle and chain, then isolate the cause—flapper, fill valve, or flush valve seat—or tell you when to call a plumber.

Troubleshooting · Home plumbing
10–20 min
What you'll need
  • Replacement flapper (if needed; universal flappers fit most toilets)
  • Towel to protect the lid and catch drips
Step 1 of 6

Quick triage — pick your path

Get started

Choose the option that matches what you see. You can jump straight to that section.

Show full guide

Steps

Goal: Confirm the symptom, check the handle and chain, then isolate the cause—flapper, fill valve, or flush valve seat.

  • Press the handle and watch the tank and bowl.
  • Good: Nothing happens or the flush is weak—mechanism fault. Proceed to Check handle and chain.
  • Bad: Toilet flushes normally—you may have a different problem (e.g. clog). See How to unclog a drain or a toilet-specific clog guide.

Check handle and chain

Goal: Rule out handle and chain issues.

  • Lift the tank lid and set it on a folded towel. Press the handle and watch the flapper.
  • Confirm the handle lifts the chain and the flapper opens. Adjust the chain to have about half an inch of slack when the flapper is closed.
  • Good: Handle moves the flapper and chain has correct slack. Proceed to Fix the flapper.
  • Bad: Handle loose or does not move the chain—tighten the nut inside the tank or replace the handle.

Fix the flapper

Goal: Replace a worn or warped flapper so the toilet flushes properly.

  • Inspect the flapper for cracks, warping, or mineral buildup. If the flush valve seat feels rough, smooth it with fine sandpaper.
  • Unhook the old flapper from the pegs and disconnect the chain. Install the new flapper and reconnect the chain with about half an inch of slack.
  • Check the water level—it should sit about one inch below the top of the overflow tube. Adjust the float if too low.
  • Good: Flapper replaced and water level correct—the toilet should flush.
  • Bad: Flush valve seat cracked or pitted—call a plumber.

When to get help

Call a plumber if:

  • You have replaced the flapper and adjusted the chain but the toilet still does not flush.
  • The flush valve seat is cracked or pitted beyond light sanding.
  • The tank or bowl is cracked.

Verification

  • The toilet flushes fully when you press the handle.
  • Water swirls in the bowl and drains completely.
  • The tank refills and the flapper seals—no running after the flush.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Confirm symptom Verify the toilet does not flush or flushes weakly.
  2. Handle and chain Check the handle moves the flapper; adjust chain slack.
  3. Flapper and water level Replace flapper if damaged; adjust water level.
  4. Call a plumber Flush valve seat cracked, tank cracked, or repeated failures—call a plumber.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Whether the handle moves the flapper
  • Chain slack and condition
  • Flapper condition
  • Water level in tank
  • Steps already tried

Does the toilet not flush or flush weakly?

Press the handle. If nothing happens or the flush is weak, the flush mechanism has failed.

Press the handle. Watch the tank and bowl. Good: no flush or weak flush—mechanism fault. Bad: toilet flushes normally—different problem (e.g. clog).

Yes No

You can change your answer later.

Does the handle move the flapper?

The handle should lift the chain and open the flapper. If not, the handle or chain is the issue.

Lift the tank lid. Press the handle. Watch the flapper. Good: handle lifts chain and flapper opens—check chain slack and flapper. Bad: handle loose or does not move chain—tighten or replace handle.

Yes No

You can change your answer later.

Does the chain have about half an inch of slack?

Too much or too little chain prevents a good flush. Adjust the chain.

Check the chain when the flapper is closed. It should have about half an inch of slack. Adjust by moving to a different link. Good: chain has correct slack. Bad: chain too tight or too loose—adjust it.

Yes No

You can change your answer later.

Is the flapper intact and does it open and close properly?

A worn or warped flapper may not open fully or seal. Replace if damaged.

Inspect the flapper. Check for cracks, warping, mineral buildup. Replace if damaged. Confirm it opens fully when chain lifts and seals when released. Good: flapper works—check water level. Bad: flapper damaged—replace it.

Yes No

You can change your answer later.

Is the water level about one inch below the overflow tube?

Low water causes weak flush. Adjust the float to raise the level.

Check the water level. It should sit about one inch below the top of the overflow tube. Adjust the float if too low. Good: level correct—toilet should flush. Bad: fill valve or flush valve seat issue—call a plumber.
Question

Is the water level correct?

Continue

You can change your answer later.

Call a plumber

Call a plumber if you have replaced the flapper and adjusted the chain but the toilet still does not flush, if the flush valve seat is cracked or pitted, or if the tank or bowl is cracked.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why would a toilet not flush?
Common causes: handle not connected to the flapper, chain too tight or too loose, worn or warped flapper that does not open or seal, or low water level in the tank. Check the handle and chain first, then the flapper.
Can I fix a toilet that will not flush myself?
Yes. You can adjust or replace the handle, chain, and flapper with basic tools. A new flapper costs about $5–15. If the flush valve seat is cracked, call a plumber.
When should I call a plumber for a toilet that will not flush?
Call a plumber if you have replaced the flapper and adjusted the chain but the toilet still does not flush, if the flush valve seat is cracked or pitted, or if the tank or bowl is cracked.

Rate this guide

Was this helpful?

Continue to