Why Your Toilet Keeps Running and How to Fix It

If your toilet keeps running long after you flush it, you’re not alone. A running toilet is one of the most common household plumbing problems—and one of the most annoying. That constant trickle of water isn’t just irritating; it’s also costing you money on your water bill and wasting a precious resource.

In this post, I’ll break down why your toilet keeps running and show you step-by-step how to fix a toilet that keeps running constantly without having to call a plumber (unless you really need to).

Common Causes of a Running Toilet

A toilet that won’t stop running usually means there’s a problem with one of the internal parts inside the tank. Here are the most common culprits:

1. Flapper Isn’t Sealing Properly
   The flapper is a rubber piece at the bottom of your toilet tank that lifts up when you flush, allowing water to flow into the bowl. If it doesn’t seal tightly afterward, water will keep leaking into the bowl, triggering the fill valve to keep running.

Signs of a bad flapper:

• You hear a slow trickling sound.
• The flapper looks warped, worn, or doesn’t sit flush.

2. Float Is Too High or Too Low
   The float controls the water level in the tank. If it’s set too high, water will rise and spill into the overflow tube, causing the fill valve to keep cycling on and off.

Symptoms:

• Water in the tank reaches the top of the overflow tube.
• Toilet randomly refills even without flushing.

3. Fill Valve Is Faulty
   The fill valve (sometimes called a ballcock) controls the flow of water into the tank. If it’s not shutting off properly or has mineral build-up, it might continue running.
4. Chain Issues
   If the chain connecting the flapper to the flush handle is too tight or too loose, it can prevent the flapper from sealing properly.

Tools You Might Need

• Adjustable wrench
• New flapper (if replacing)
• Replacement fill valve (optional)
• Bucket and sponge or towels
• Rubber gloves (optional but recommended)

Step-by-Step: How to Fix a Toilet That Keeps Running Constantly

Let’s walk through the troubleshooting and repair process.

Step 1: Remove the Tank Lid and Inspect
Carefully lift the tank lid and set it aside. Take a look inside. Flush the toilet and observe what happens:

• Does the flapper close fully?
• Does the water level rise too high?
• Does the fill valve shut off?

Step 2: Check and Adjust the Flapper
Push down gently on the flapper after flushing. If the toilet stops running, the flapper is likely the issue.

Fix it:

• Turn off the water supply (usually behind the toilet).
• Flush to empty the tank.
• Disconnect the flapper from the overflow tube.
• Take it to the hardware store and buy the same size/type.
• Install the new one and reconnect the chain with a bit of slack.

Step 3: Adjust the Float
If water is going into the overflow tube, the float might be set too high.

Fix it (depends on float type):

• Float arm (older toilets): Gently bend the arm down to lower the water level.
• Float cup (newer toilets): Squeeze the clip on the rod and slide the float down.

Aim to set the water level about 1 inch below the top of the overflow tube.

Step 4: Shorten or Loosen the Chain
A chain that’s too short holds the flapper up, while a chain that’s too long can get stuck under the flapper.

Fix it:

• Adjust the clip so there’s about ½ inch of slack.
• Make sure the chain isn’t getting caught or kinked.

Step 5: Replace the Fill Valve (if needed)
Still not fixed? Your fill valve might be worn out.

Fix it:

• Turn off the water supply.
• Flush and sponge out the tank.
• Use a wrench to unscrew the locknut under the tank.
• Remove the old fill valve.
• Insert the new one according to the instructions on the package.
• Turn the water back on and check for leaks.

Most universal fill valves are easy to install and cost under $20.

Bonus Tip: Add Food Coloring to Detect Leaks
Still not sure if your flapper is leaking? Add a few drops of food coloring to the tank and wait 15-20 minutes without flushing.

If colored water appears in the bowl, you’ve got a slow leak. Replace the flapper.

How Much Water Is Your Toilet Wasting?

A running toilet can waste up to 200 gallons of water per day. That’s over 6,000 gallons a month—enough to fill a medium-sized swimming pool. Not only is it bad for the environment, but it also adds up on your water bill.

When to Call a Pro

If you’ve tried all the steps above and your toilet still runs—or you notice water pooling around the base—you may have a more serious issue, like a cracked tank or a problem with the shutoff valve. That’s when it’s time to call in a pro.

Recap: Why Toilets Keep Running

Problem	Fix
Worn flapper	Replace flapper
High float	Lower float level
Chain too tight/loose	Adjust chain length
Faulty fill valve	Replace fill valve

Still Dealing with a Running Toilet?

Don’t let that water bill keep climbing. Whether you need help with the fix or just want it handled fast and right the first time, I’ve got your back. You may need emergency toilet repair in Detroit.

Another thing to keep in mind is the age of your toilet. Older toilets tend to have more worn-out parts and may not be as efficient as modern models. If you find yourself frequently fixing the same issues or notice your water bill climbing despite repairs, it might be time to consider upgrading to a newer, water-saving toilet. Newer models use less water per flush and have improved internal mechanisms that reduce the chance of running problems.

Finally, don’t underestimate the value of routine inspections. Every few months, take a quick look inside the tank to check for any obvious wear or leaks. Catching problems early can save you from a big water waste headache and costly repairs down the line. A few minutes of preventive maintenance can keep your toilet running smoothly and your wallet happy.

Understanding how your toilet’s internal components work can also help you diagnose issues more quickly in the future. The tank is designed to refill and shut off automatically after every flush, thanks to the coordinated action of the flapper, fill valve, and float. When you flush, the flapper lifts, releasing water into the bowl. Once the tank empties, the flapper drops back down to seal the opening. Meanwhile, the float drops with the water level, signaling the fill valve to open and refill the tank. When the float rises to a set point, it tells the fill valve to shut off. If any of these parts don’t function properly, water will continue to flow, causing the running toilet.

Another tip to keep in mind is that hard water can seriously shorten the lifespan of toilet parts. Minerals in hard water build up over time on the flapper and fill valve, causing them to stick or wear unevenly. If you live in an area with hard water, consider checking your toilet parts more frequently and cleaning them with vinegar or a mild descaling agent. In some cases, installing a water softener for your home can reduce mineral buildup and extend the life of your plumbing fixtures, saving you money and hassle in the long run.