DIY May Be Possible Avg. cost: $125
Running Toilet: Causes, Fixes & When to Call a Plumber
A running toilet is caused by a faulty flapper, float, fill valve, or flush valve. Open the tank, identify which part isn't sealing, and replace it. Parts cost $5–$25 at any hardware store.
What Causes Running Toilet?
- Worn or warped flapper not sealing properly
- Float set too high, causing constant overflow into overflow tube
- Failed fill valve
- Cracked flush valve seat
- Chain tangled or too short between flapper and handle
How to Fix Running Toilet: Step-by-Step
- 1Remove the tank lid and observe which component is malfunctioning
- 2Check if water is entering the overflow tube (float too high)
- 3Check if the flapper is sealing — press it down; if toilet stops running, replace the flapper
- 4Adjust the float arm or ball float to lower the water level
- 5Replace the fill valve if adjustments don't resolve constant running
When Should You Call a Plumber?
Call a plumber if the toilet runs intermittently (phantom flush), the flush mechanism is integrated and complex, water is leaking at the base, or you've replaced components and it still runs.
How Much Does Running Toilet Repair Cost?
Average Cost $125
Typical Range $75 – $250
Costs vary by location, severity, and whether emergency service is needed. Prices shown are national averages. Get a free quote from a local plumber →
Frequently Asked Questions About Running Toilet
- A constantly running toilet wastes 200–400 gallons per day — about $100–$200 added to your monthly water bill. A phantom flusher (running for 30 seconds every few hours) wastes roughly 2,000 gallons per month.
- Phantom flushing is when the toilet refills itself every 10–30 minutes without being used. It's caused by water slowly leaking past a worn flapper into the bowl, eventually dropping low enough to trigger the fill valve.
- Put a few drops of food coloring in the tank. If the color appears in the bowl within 15 minutes without flushing, the flapper isn't sealing and needs replacement.