Why Does My Toilet Keep Running? Causes, Fixes and When to Call a Plumber

Why a running toilet matters

A toilet that keeps running is more than an annoying sound. A constantly refilling tank can waste a large amount of water every day, and in Texas summers when water use is already high, that shows up fast on your bill. The good news is that most running toilets have a simple cause and a quick fix.

The 5 most common causes

1. A worn flapper. The rubber flapper at the bottom of the tank seals water in. Over time, chlorine and hard Texas water make it stiff or warped, so water slowly leaks into the bowl and the tank keeps refilling.

2. A chain that is too short or tangled. If the lift chain holds the flapper slightly open, water runs nonstop.

3. Fill valve set too high. If the water level rises above the overflow tube, it spills into the bowl continuously.

4. A failing fill valve. Fill valves wear out and may not shut off fully, causing a hiss or periodic refill (often called ghost flushing).

5. A cracked overflow tube or flush valve. Less common, but it requires replacing the flush valve assembly.

Quick checks you can do

Lift the tank lid and look at the water level. It should sit about an inch below the top of the overflow tube. Add a few drops of food coloring to the tank and wait 15 minutes without flushing. If color appears in the bowl, the flapper is leaking.

If you are not comfortable working inside the tank, or the toilet is also leaking at the base or overflowing, it is time for professional toilet repair.

When a running toilet is a bigger problem

If the toilet runs and also gurgles, or water rises in the tub when you flush, the issue may be a blocked drain or sewer line. In that case you need drain cleaning or a sewer camera inspection, not just new tank parts. A toilet overflowing with sewage is an emergency, and our 24/7 emergency plumbers can help.

Repair or replace?

Most running toilets only need a new flapper or fill valve. If your toilet is very old, cracks, rocks on the floor or clogs constantly, replacing it with a modern high-efficiency model may save water and frustration. Our plumbers can handle toilet replacement the same day in most Texas cities.

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