A toilet that keeps running is usually caused by a worn flapper, a faulty fill valve, or an incorrect float setting. These are inexpensive fixes ($100 to $350) but can waste significant water and raise your bill. Replacing the flapper often solves it; persistent issues may need a fill-valve rebuild.
Likely causes
| Cause | What's happening |
|---|---|
| Worn flapper | The most common cause; a cheap, quick fix. |
| Faulty fill valve | Water won't shut off at the right level. |
| Float set too high | Water spills into the overflow tube. |
- Overflowing tank or bowl causing flooding
If anyone is in danger, or you smell gas, leave the home and call 911 or your utility immediately.
Frequently asked questions
What causes toilet keeps running?+
Several issues can produce this symptom, from simple maintenance items to component failure. The likely causes table on this page lists what each cause looks like so you can describe the problem accurately when you request quotes.
Should I call someone right away?+
Call promptly if you see active water, no cooling during Arizona summer heat, burning smells, or repeated breaker trips. Otherwise, gather details and compare two written quotes before approving repairs.
Can PlumbAirAZ diagnose the problem?+
PlumbAirAZ is an Arizona plumbing and HVAC pricing and referral marketplace, not a contractor. We publish local price ranges and route your quote request to independent licensed service providers who contact you directly.
Related pages
Page Summary
- Topic
- Toilet Keeps Running
- Location
- Arizona
- Best for
- Homeowners diagnosing the issue
- Primary action
- Request a professional diagnosis
- Related services
- See related pages
- Last reviewed
- June 2026
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Last reviewed: June 2026
PlumbAirAZ.com is a pricing, education, and referral marketplace. We do not perform the work unless expressly stated. Your request may be shared with or sold to independent HVAC, plumbing, or home service providers that may contact you about your project.