How to Fix a Running Toilet: 12 Easy Steps

You might not see the problem, but you’ll feel it on your next water bill. A running toilet is one of the most overlooked plumbing issues, but it’s easy to fix if you know what to check. In this guide, Heritage Services shares how to fix a running toilet so you can stop the flow and keep your system working right.

Most Common Causes of a Running Toilet

Before you grab your tools, let’s talk about what’s likely causing the problem in the first place. These are the most common causes we see during service calls:

• Worn-out or warped flapper – The rubber flapper covers the flush valve at the bottom of the tank. When you flush, it lifts up, and when the flush is done, it’s supposed to fall back down and seal tightly. If it’s warped, cracked, or doesn’t sit flat, water keeps leaking into the toilet bowl.
• Flapper chain problems – If the chain that connects the flush lever to the flapper is too tight, the flapper won’t close all the way. If it’s too loose, the flapper won’t lift fully when you flush. You need the right chain length with just a little slack so the flapper closes securely.
• Water level too high – If the water level in the tank is set too high, it flows over into the overflow tube, keeping the water running constantly.
• Float problems – The float controls how much water enters the tank after a flush. If it’s not set at the right height, it tells the fill valve to keep filling the tank even when it’s already full. A small float adjustment can usually fix this.
• Faulty fill valve – If your old fill valve is worn out, sticking, or not sealing properly, it may keep running even when the tank is full.
• Mineral buildup or debris – Hard water in Oklahoma can cause mineral buildup on internal toilet parts, which can keep things from functioning properly.

Most of these issues are simple to identify and even easier to fix. Let’s walk through how to do it.

A Guide to Fixing Running Toilets

To start, lay out a towel or sponge to catch any drips. Keep a bucket nearby just in case you need to drain part of the toilet tank. Now, let’s get to work.

Tools and Replacement Parts You May Need

Below is a list of the things you’ll likely need. Most of these are available at your local hardware store:

• Adjustable wrench
• Flathead and Phillips screwdriver
• Needle-nose pliers
• New flapper (make sure it matches the size and style of your old flapper)
• New fill valve (if needed)
• Towels or sponge
• Small bucket

Step 1: Shut Off the Water Supply

Find the water supply valve located behind or below the toilet, usually where the water line connects to the wall. Turn it clockwise to shut off the water. Then flush the toilet to empty the tank. Use a sponge or towel to soak up any water left at the bottom of the tank.

Step 2: Remove the Toilet Tank Lid and Inspect the Interior

Carefully lift the tank lid and place it somewhere safe because it’s fragile. Inside the tank, you’ll see several key parts: the flapper, the fill valve, the overflow tube, the flush handle, the chain, and the float. Take a minute to look around and get familiar.

Step 3: Check the Flapper for Wear, Warping, or Misalignment

The rubber flapper is usually the first place we look. If it’s stiff, brittle, or misshapen, it won’t seal the flush valve opening, allowing water to constantly drip into the bowl. Gently push down on it with a stick or the back of a screwdriver. If the toilet stops running, you’ve found your problem, and it means it’s time to replace it.

Step 4: Adjust or Replace the Flapper Chain

Now look at the chain that connects the flush lever to the flapper. If it’s too short or too tight, it holds the flapper slightly open. If it’s too long, the flapper might not even lift when you flush. You want a little slack, enough that the flapper can open fully and close easily. If needed, just unhook the chain and reconnect it at a different link to adjust the chain length.

Step 5: Inspect the Fill Valve for Proper Operation

Next, look at the fill valve. This controls the incoming water after each flush. With the tank drained, check for obvious cracks, mineral buildup, or parts that look loose or out of place. If the old fill valve looks worn or if water was constantly running before you shut it off, you may need to replace it.

Step 6: Adjust the Water Level in the Tank

Find the fill line marked on the inside wall of the tank or on the overflow tube. This is the right height for the water. If the water is too high, it flows into the overflow tube, keeping the toilet running. Use the float adjustment screw or clip on your fill valve to lower the water level. You want it about an inch below the top of the overflow tube.

Step 7: Check the Float (Ball Float or Cup Float)

Toilets use either a ball float on a metal arm or a cup-style float that slides up and down on the fill tube. For a ball float, you can gently bend the arm downward to lower the float height. For a cup float, look for the plastic clip or adjustment screw that controls where the float stops. A small tweak can make a big difference in how your tank fills.

Step 8: Inspect the Overflow Tube for Issues

If the overflow tube is cracked, too short, or sitting too low in the tank, it can cause water to leak constantly. If your fill valve is working correctly but water is still flowing into the overflow, your tube may be part of the problem. Make sure it’s clean, upright, and at the proper height.

Step 9: Replace the Flapper if Necessary

If your flapper is damaged or not sealing properly, you’ll need to replace it. Disconnect the old flapper from the flush valve pegs and unhook the chain. Take it with you to the hardware store to match the size. Once you have the new flapper, snap it into place and reattach the chain with just enough slack to allow it to fully open and close.

Step 10: Install a New Fill Valve if Necessary

If your old fill valve isn’t functioning properly, even after cleaning or adjusting, it’s time for a new one. Turn off the water supply, drain the tank again, and use a wrench to disconnect the lock nut under the tank that holds the fill valve in place. Remove the water supply line if needed. Follow the instructions on your new fill valve kit to install it and reconnect the water line. Be sure to set the float and fill level before turning the water back on.

Step 11: Turn the Water Back On and Test the Toilet

Slowly turn the water supply valve counterclockwise to fill the tank. Watch as the float rises and the fill valve shuts off. If everything’s working right, the water should stop at the correct water level, and the toilet bowl should fill without overflow.

Step 12: Confirm the Toilet Stops Running After Multiple Flushes

Flush the toilet a few times. Watch how the flapper behaves, how the water flows, and how the fill valve shuts off. If the toilet stops running and everything seems normal after a few tries, congrats—you’ve fixed it!

Preventive Maintenance Tips to Avoid Future Toilet Leaks

Once you’ve got your toilet back in working order, there are a few simple habits that can help you avoid the same issue down the road:

• Lift the tank lid every few months to inspect the internal parts
• Clean sediment from the flapper, fill valve, and float using vinegar and an old toothbrush
• Don’t use bleach tablets or harsh cleaners inside the toilet tank, as they can degrade rubber parts
• Watch for high water bills, which may hint at silent leaks
• If the toilet runs overnight or refills randomly, something’s not sealing properly
• Replace worn parts early if you notice they’re stiff, misshapen, or feel brittle

Simple maintenance goes a long way. Just staying a little alert can help you save money and avoid surprise repairs.

When Does a Running Toilet Require a Professional Plumber?

There are plenty of toilet problems you can handle on your own, but not all of them. It’s a good time to call in a professional plumber if:

• You’ve tried these steps, and the toilet is still running
• Water is leaking from the base of the toilet onto the floor
• You notice corrosion, cracked parts, or signs of a larger pipe problem
• You’ve replaced parts, but the toilet won’t stop overfilling or leaking
• You’re dealing with multiple toilets acting up at once

A licensed plumber can quickly spot issues with the valve, supply line, or hidden cracks in the tank or flush valve that might be hard to see without the right tools. We also check for mineral buildup and sediment that may be affecting other fixtures in your home.

Toilet Running? Let the Pros Handle the Next Pull

Sometimes, you can do everything right, and the water still keeps slipping through the hole. If your fix didn’t stick or you’re losing gallons overnight, it’s time to call Heritage Services. We’re your trusted name in bathroom plumbing in Oklahoma City, and we’ll get the problem solved for good.

Contact us today at 405-348-5555 to learn more.