How to fix a running toilet

Is there a steady trickle or a constant on-off cycling noise coming from your toilet? That running sound means there’s a leak in your toilet, usually caused by a worn-out flapper or toilet fill valve. These are parts inside the toilet tank that allow flushing and refilling. In most cases, you can repair these toilet problems yourself.

Knowing how to stop a running or leaky toilet is an important home-improvement skill that can prevent a high water bill and water waste. Since toilets have changed little over the years, this home repair is generally an easy fix. Our step-by-step DIY guide will show you how.

Skill level: Easy

Cost: Under $20

Repair time: 15 - 60 minutes

Tools required: None

A running toilet is often caused by a faulty flapper. The flapper is the rubber stopper or seal that retains refill water in the tank after each flush. It also opens the valve when the handle lever is pressed. Toilet flappers can deteriorate after four or five years, causing a steady running sound as water leaks out of the tank. Here’s how to diagnose and replace a worn-out flapper:

1. Turn off the water supply. The shutoff valve is typically located directly under the toilet tank.

2. Remove the tank lid to locate the flapper.

3. Test the flapper: Push down on the flapper to see if it’s sealing correctly. If water immediately stops running, the flapper is defective.

4. Flush the toilet to drain water from the tank, and unhook the chain attached to the flapper.

5. Note how the flapper attaches to the tank. This will help you identify the correct replacement part to buy.

6. Purchase a replacement flapper. This usually costs about $10.

7. Follow the product instructions for installing the new flapper valve. Make sure there’s very little slack in the flapper chain when reconnecting it to the valve.

A worn-out fill valve—the device that allows water to refill the tank after each flush—can also cause running or leaky toilets. The valve, also called a “ballcock,” is located on the left inner side of the tank. If it’s not working properly, the water level can get too high when the tank refills. Adjusting the fill valve can solve this issue. Here’s how to do it yourself:

1. After shutting off the water, remove the toilet tank lid, and flush the toilet.

2. Hold down the flush handle to drain the water out of the tank. The large plastic “float” will drop as water empties.

3. After the tank refills, check the water level. It should be one-half to one-inch below the top of the tank.

4. If the water level is too high, you can lower the “float setting” in the fill valve. This is done by squeezing the clip on the float’s metal arm—or slightly bending that rod—so the ball floats deeper in the tank.

5. Continue to flush the toilet and adjust the float setting until the tank is filled to the proper level.

6. If water levels continue to run high, the fill valve may need to be replaced. That repair can take additional time, tools, and effort.

When a DIY toilet repair fails to stop a running toilet, there may be a more complex underlying toilet problem. Another part—the fill tube or flush valve, for example—might need to be repaired or replaced. If you’re uncomfortable delving deeper into DIY toilet repair, it’s time to call a professional.

When choosing plumbing services, it’s important to hire a seasoned pro. That’s because more challenging plumbing projects require a higher level of expertise to fix the problem and protect your home. Here’s how to find a good plumber:

1. Verify that the plumber is licensed, bonded, and insured

2. Check their reviews on Yelp and their rating with the Better Business Bureau (BBB)

3. Be wary of someone who gives quotes over the phone before diagnosing the problem

4. The plumber should provide an on-site estimate

5. Double check the quote to make sure it includes toilet repair parts and labor