A running toilet isn’t just a nuisance, it’s a massive source of water waste. In a single day, a running toilet wastes up to 200 gallons of water. That’s 6,000 gallons in a month! Don’t just sit there listening to it, hoping it will “fix itself.” Put your problem-solving skills to work and get to the bottom of it.

Most of the time it doesn’t take a plumber to fix a running toilet. Every homeowner should know how to fix a running toilet without calling a plumber. It helps to start with a basic understanding of how your toilet actually works, and what it means to say that your toilet is running.

How a Toilet Flushes

Most of us can identify when our toilet is running, but do you actually know what that means? You need to understand how a toilet flushes in order to understand how to fix a running toilet.

The basic mechanism behind how your toilet functions is pretty simple. Inside your toilet tank, there is a flapper that seals the drain hole that leads into the toilet bowl. When you press the lever to flush the toilet, that flapper is lifted, allowing water to rush into the toilet bowl.

That sudden influx of water triggers a siphon effect in the toilet bowl that sucks the dirty water and waste down through the U-bend and into the sewer. When the tank is emptied, the flapper reseals the drain hole.

Meanwhile, the fill valve works to refill the tank, sending some water through the fill tube to the overflow tube, which empties back into the toilet bowl. When the water level rises to just under the top of the overflow tube, the float valve (that floating ball you see on the surface of the water) signals the fill valve to shut off the flow of water.

And that’s how a toilet flushes!

What it Means When a Toilet is Running

When your toilet is running, you’re hearing a steady stream of water. After a toilet flushes, there should be no more water movement. That means if water continues to run after the flush, there’s a leak somewhere inside the toilet. Your job as handy-dandy homeowner is to locate the leak and fix it!

Common Causes & How to Fix a Running Toilet

1. Flapper Chain Length

The length of the chain attached to the flapper should be perfectly calibrated so that it lifts up when the flush lever is pulled, but releases enough slack to reseal when the tank is empty. A chain that’s too short won’t enable the flapper to fully seal, leaving the drain hole always slightly open. The flapper won’t lift up when the flush level is pulled if the chain is too long.

If there’s extra length on the chain, you can just move the clip down to give it more slack. Otherwise, replace the chain with any aluminum ball chain you can find at the hardware store.

2. Broken Flapper

After extended use, a flapper can become warped or even break. A broken or warped flapper will not be able to effectively seal the drain hole, causing water to leak into the toilet bowl.

To check whether your flapper is warped, lift the lid on the tank and then flush the toilet to drain the tank. Grab the flapper and inspect it for discoloration, mineral deposits, misshapenness, or any breakage in the rubber. If you spot a problem, no worries. Flappers are very cheap to replace.

3. Faulty Fill Tube

When the toilet tank refills, water travels from the fill valve through the refill tube into the overflow tube, which empties back into the toilet bowl. The fill tube should be above the water line when the tank is full. If it is not, cut the end back until it rises above the water line.

4. Faulty Fill Valve + Float

The fill valve, which controls water flow into the tank, is connected to the float ball. The float ball is designed to float level on the surface when the water reaches a certain level inside the tank (½-inch to 1-inch below top of overflow tube). This tells the fill valve to shut off and cease filling the tank. If the float is misadjusted, it won’t be able to correctly gauge the water level. The water level will rise above the overflow tube and drain continuously into it.

First, try bending the float arm (the rod connecting the float to the pump). Adjusting the float arm so the float is lower will signal the fill valve to shut off sooner. Flush the toilet. If it’s still running, you may need to replace the fill valve itself.

If you’ve worked through these common causes of a running toilet and you’re still unable to fix the problem, it’s time to call in the pros. Dial your trusted plumber and schedule a service call.

Have a toilet that keeps running no matter how many times you fix it? It may be time to replace your toilet.