How to Fix a Running Toilet in 15 Minutes

What Causes a Running Toilet?

Before diving into repairs, it helps to understand how your toilet works. When you flush, the handle lifts a flapper at the bottom of the tank, releasing water into the bowl. After flushing, the flapper closes and the tank refills until the float tells the fill valve to stop.

A running toilet usually means one of these components isn't working correctly:

• The flapper — worn or warped, not sealing properly
• The float — set too high, causing constant overflow
• The fill valve — worn out and not shutting off

Tools You'll Need

Gather these items before you start: adjustable pliers or a wrench, a towel or sponge, and potentially a replacement flapper (available at any hardware store for a few dollars).

Step 1: Identify the Problem

Remove the tank lid and observe what's happening. Is water constantly trickling into the overflow tube? Does the flapper look warped or have mineral buildup? Is the float positioned correctly?

Pro tip: Add a few drops of food coloring to the tank. If color appears in the bowl without flushing, your flapper isn't sealing.

Step 2: Adjust the Float

If water is running into the overflow tube, your float is set too high. For ball floats, bend the arm down slightly or adjust the screw at the valve. For cup floats, squeeze the clip and slide it down the rod.

The water level should be about 1 inch below the top of the overflow tube.

Step 3: Replace the Flapper

If the flapper is the culprit, replacing it is straightforward. First, turn off the water supply valve behind the toilet. Flush to empty the tank, then unhook the old flapper from the overflow tube and disconnect the chain from the handle arm.

Install the new flapper by hooking it onto the overflow tube ears and connecting the chain to the handle arm. Leave about half an inch of slack in the chain.

Step 4: Test Your Repair

Turn the water back on and let the tank fill. Listen for the fill valve to shut off completely. Watch for any water movement in the bowl (the food coloring test helps here). Flush a few times to make sure everything works smoothly.

When to Call a Professional

If you've tried these fixes and your toilet still runs, or if you notice cracks in the tank or persistent leaks at the base, it's time to call a plumber. Some issues, like a damaged fill valve or cracked porcelain, require professional attention.