Why Is My Toilet Running Constantly?

Published September 2026 · Pro Plumber Laveen AZ

A constantly running toilet wastes water and can drive up your utility bill. The good news is that it's usually caused by one of a few common issues inside the tank.

Most Common Causes

1. Worn Flapper

The flapper is the rubber seal at the bottom of the tank that opens when you flush and closes to let the tank refill. Over time, flappers warp, crack, or develop mineral buildup — especially in Laveen's hard water — preventing a tight seal. Water leaks continuously into the bowl, triggering the fill valve to keep running.

2. Faulty Fill Valve

The fill valve controls water flowing into the tank after a flush. If it's worn or malfunctioning, it may not shut off properly, causing the tank to overfill and water to flow into the overflow tube.

3. Float Set Too High

The float tells the fill valve when to stop. If it's set too high, the water level rises above the overflow tube, and the toilet runs to prevent flooding.

4. Overflow Tube Issues

If the overflow tube is cracked or too short, water continuously drains into the bowl. This requires the tube to be replaced.

5. Chain Problems

The chain connecting the flush handle to the flapper can be too short (keeping the flapper partially open) or too long (getting caught under the flapper).

When to Call a Professional

While some of these fixes are straightforward, call a professional plumber if:

A running toilet seems minor, but left unfixed it can waste thousands of gallons over time. If you're in Laveen, call (602) 404-6039 and we'll connect you with a local plumber who can diagnose and fix it quickly.

Toilet Won't Stop Running?

Call now — we'll connect you with a local plumber who can fix it fast.

Call (602) 404-6039 Now
Call (602) 404-6039