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Bathroom troubleshooting

Why Does My Toilet Keep Running?

Understand the common causes of a constantly running toilet, safe checks you can make, likely costs, and when to call a plumber.

Safety-reviewed informational guidance Updated 2026-08-12

What this usually means

A toilet that keeps running usually has a tank component that is not sealing or shutting off correctly. The most common causes are a worn flapper, a tight chain, or a fill valve or float that needs adjustment.

Likely causes

1

Worn or misaligned flapperThe rubber seal at the tank bottom can become stiff, dirty, or off-centre, allowing water to leak into the bowl.

2

Fill valve or float adjustmentIf gently lifting the float stops the water, the fill control is the stronger candidate.

3

Flush chain problemA caught or overly tight chain can hold the flapper slightly open.

4

Water level set too highWater flowing into the open overflow tube points to a level or fill-valve issue.

Safe checks you can make

  • Listen and look for continuous water entering the bowl.
  • Remove only the tank lid and set it safely on a towel.
  • Check whether the chain has a little slack.
  • Compare the tank water line with the top of the overflow tube.

When to call a professional

Call a plumber if the shutoff valve is stuck, the toilet is overflowing, the tank is cracked, or accessible adjustments do not stop the flow.

Common questions

Is a running toilet an emergency?

Usually it is low urgency, but it wastes water. An overflowing toilet or water reaching the floor needs immediate attention.

How much does a running-toilet repair cost?

A basic DIY flapper or fill valve often costs about $8–$35. A typical professional visit may be roughly $120–$250, varying by location and complexity.