Why Does My Toilet Keep Running? 7 Common Causes (And When It’s Time to Call a Plumber)

A toilet that won’t stop running might not seem like a major plumbing issue, but it can waste hundreds of gallons of water every week and drive up your utility bill. In many cases, the problem starts with a small part inside the toilet tank. Left unchecked, however, it can become a bigger and more expensive repair.

If you’ve noticed your toilet randomly refilling, constantly running, or making hissing noises long after you’ve flushed, here’s what could be causing the problem.

1. A Worn-Out Toilet Flapper

The flapper is the rubber seal at the bottom of your toilet tank. Every time you flush, it lifts to allow water into the bowl before sealing again.

Over time, the rubber begins to wear out, crack, warp, or collect mineral deposits. When the flapper no longer creates a tight seal, water slowly leaks into the bowl, causing the fill valve to keep turning on.

Signs of a bad flapper include:

• The toilet refills every few minutes.

• You hear water running on and off throughout the day.

• The toilet seems to flush by itself.

• Food coloring added to the tank appears in the bowl without flushing.

A worn flapper is one of the most common—and fortunately one of the easiest—toilet repairs.

2. A Faulty Fill Valve

The fill valve controls how much water enters your toilet tank after each flush.

As the valve ages, internal components can wear out or become clogged with sediment. When that happens, the valve may never completely shut off, causing water to continue flowing into the tank.

Common symptoms include:

• A constant hissing sound.

• Water continuously running.

• The tank taking much longer than normal to refill.

• Water spilling into the overflow tube.

Replacing a faulty fill valve usually restores normal operation.

3. The Float Is Set Too High

The float tells the fill valve when enough water has entered the tank.

If the float is adjusted too high, water rises above the proper level and spills into the overflow tube. That continuous overflow causes the fill valve to keep adding water.

Sometimes adjusting the float solves the issue, but if it won’t stay in place, the fill valve itself may need replacement.

4. Mineral Buildup Inside the Tank

Over time, minerals naturally found in water can build up on moving toilet components.

Mineral deposits may prevent the flapper from sealing properly or interfere with the fill valve’s ability to shut off.

Cleaning the affected parts may help temporarily, but heavily worn components often need replacement.

5. A Damaged Overflow Tube

The overflow tube is designed to prevent your toilet tank from overflowing.

If the tube develops cracks or damage, or if water levels remain too high, water will continuously drain through it into the bowl.

This keeps the fill valve cycling over and over again.

6. Loose or Worn Toilet Components

Inside every toilet tank are several moving parts that experience wear with every flush.

Over time you may develop:

• A chain that’s too short or too long.

• A loose flush handle.

• Corroded hardware.

• Worn connecting pieces.

Even something as simple as a chain getting caught underneath the flapper can prevent it from sealing completely.

7. Your Toilet Is Simply Getting Old

Like any plumbing fixture, toilets wear out over time.

If your toilet is 15 to 20 years old, several internal parts may begin failing around the same time. Rather than continually replacing one component after another, replacing the entire toilet may be the more cost-effective long-term solution.

Modern toilets are also significantly more water-efficient than older models.

How Much Water Can a Running Toilet Waste?

Many homeowners are surprised to learn just how expensive a running toilet can become.

A toilet that constantly leaks can waste dozens—or even hundreds—of gallons of water every single day. That wasted water shows up on your monthly utility bill while also placing unnecessary strain on your home’s plumbing system.

Ignoring the problem almost always costs more than fixing it.

When Should You Call a Plumber?

While some toilet repairs are relatively simple, others require professional diagnosis.

It’s time to call Colonial Capital Plumbing & Septic if:

• Your toilet won’t stop running.

• You’ve replaced the flapper but the problem continues.

• Water is leaking around the base of the toilet.

• The toilet frequently clogs along with running.

• Multiple toilets in your home are acting up.

• Your water bill has suddenly increased without explanation.

Our experienced plumbers can quickly identify the cause and recommend the most cost-effective repair.

Prevent Future Toilet Problems

Routine maintenance goes a long way toward preventing unexpected repairs.

Here are a few simple tips:

• Check inside the toilet tank every few months.

• Replace worn rubber seals before they fail.

• Avoid harsh chemical cleaners inside the tank.

• Address small leaks immediately.

• Schedule plumbing inspections if your home has older fixtures.

A little preventative maintenance today can save hundreds of dollars tomorrow.

Trust Colonial Capital Plumbing & Septic

Whether your toilet needs a simple repair or a complete replacement, Colonial Capital Plumbing & Septic is here to help.

Our experienced team has been serving homeowners throughout New Bern and the surrounding communities for more than 30 years with honest service and dependable workmanship.

If your toilet keeps running, don’t keep paying higher water bills waiting for the problem to fix itself.

Call Colonial Capital Plumbing & Septic today at 252-635-1710 or contact us online to schedule fast, professional service.

We’ll get your plumbing working properly again so you can stop worrying about wasted water and unexpected repairs.