Quick answer: A toilet that won’t flush is usually one of four things: a clog (most common — grab a plunger), a low tank water level, a broken or disconnected flapper, or a faulty fill valve. Most are $0–$15 fixes you can do in minutes.
Not sure which of the four you have? The Toilet Diagnostic tool narrows it down by symptom before you start.
Every reason a toilet won’t flush, and how a plumber fixes each.
Cause 1: It’s Clogged (most common)
If the bowl fills but won’t clear, it’s a clog. A good flange plunger clears most. Still stuck? A toilet auger reaches deeper.
Cause 2: Low Water in the Tank
Lift the lid — water should sit about an inch below the overflow tube. If it’s low, the fill valve or float needs adjusting or replacing.
Cause 3: Flapper Problem
If pushing the handle does nothing, the chain may be disconnected or the flapper isn’t lifting. Reconnect the chain or replace the flapper — see our running toilet guide.
Cause 4: Weak/Partial Flush
Clogged rim jets (mineral buildup under the bowl rim) or a too-low water level cause weak flushes. Clear the jets with a wire and vinegar, and check the tank level.
When to Call a Plumber
If multiple drains back up along with the toilet, it’s a main-line clog — call a pro. For everything else, it’s a quick DIY.
Related Guides
- How to Fix a Running Toilet
- Best Toilet Plungers
- Best Toilet Fill Valves
FAQ
Why won’t my toilet flush but it’s not clogged?
Check the tank: low water level, a disconnected flapper chain, or a faulty fill valve are the usual culprits when there’s no clog.
How do I fix a weak flush?
Clear mineral buildup from the rim jets under the bowl rim with vinegar and a wire, and make sure the tank fills to about an inch below the overflow tube.
When should I call a plumber for a toilet that won’t flush?
If other drains back up at the same time — that points to a main sewer line clog, which needs a professional.
Related: How to unclog a toilet
Related: Why Does My Toilet Keep Clogging? (causes & fixes)
Fix the 12 Most Common Plumbing Problems Yourself — Free Plumber’s Handbook — including the toilet fixes plumbers charge $150+ for
Step-by-step fixes for the 12 most common problems — and exactly when to call a pro. Free and instant, from a licensed plumber. Save hundreds on calls you didn’t need.