Why is my toilet running constantly and how to stop it?

A toilet that runs constantly is easy to hear and easy to ignore. The sound comes and goes: a burst of water, then quiet, then another burst. What is happening is a fill-and-drain loop. Water escapes the tank through a failed seal, the water level drops, the fill valve tops it back up, and the cycle repeats. The toilet never reaches a stable off state, and water runs down the drain around the clock. The fix is usually a single worn part, and you can narrow it down yourself with a look inside the tank and a simple test.

Why a toilet runs constantly: the short answer

A toilet has a small number of parts that can cause it to run, and the symptoms point to the culprit. If you hear water trickling into the bowl when nothing is being flushed, the flapper is not sealing. If you hear a hiss from the tank that never stops, the fill valve is not shutting off. If the water level sits at or above the top of the overflow tube, the float is set too high. Each of those is a different fix, and checking them in order saves a trip to the hardware store for the wrong part.

The five parts that cause a running toilet

Every running toilet traces back to one of five components. Knowing which one is failing tells you whether you are looking at a simple homeowner fix or a call to a plumber.

1. The flapper, the most common cause

The flapper is the rubber seal at the bottom of the tank that lifts when you flush and drops back to seal. Rubber degrades, and in Colorado's dry air it hardens and warps faster than in humid climates. Mineral scale from Lakewood's moderately hard water, about 105 milligrams per liter for Denver Water customers, also builds up on the flapper and the valve seat. A flapper that is stiff, warped, or coated in scale does not seal, and water leaks into the bowl around the clock.

The food-coloring test finds a flapper leak in ten minutes. Put a few drops of food coloring in the tank, wait ten minutes without flushing, and look at the water in the bowl. If the bowl water is tinted, the flapper is leaking. That test catches a silent leak as well as a noisy one, and a silent leak wastes just as much water.

2. A stuck or failing fill valve

The fill valve refills the tank after a flush. When the rubber diaphragm inside wears out, the valve does not shut off completely, and you get a steady hiss that never stops. Fill valves typically last several years, and an older valve that hisses after the tank is full is usually ready for replacement rather than cleaning.

3. A float set too high

The float tells the fill valve when to stop. If it is set too high, water rises past the overflow tube and drains continuously into the bowl. Look at the water level in the tank. It should sit below the top of the overflow tube. If the water is at or above the top of the tube, the float needs adjusting down. The adjustment is usually a screw on the fill valve or a clip on the float arm, depending on the design.

4. A worn flush valve seat

The flush valve seat is the ring the flapper presses against. Mineral buildup or a nick in the seat means a new flapper still will not seal. You will know this is the issue if you replace the flapper and the toilet still runs. The seat needs to be cleaned or replaced, and replacing a flush valve assembly is a bigger job than swapping a flapper.

5. A disconnected or misplaced refill tube

The refill tube clips onto the overflow tube and directs water into the bowl. If it is disconnected, or pushed too far down into the overflow tube, water can siphon continuously. Reseat the clip so the tube sits just above the water line. This is a quick check, and it is worth doing before you buy any parts.

How to stop a running toilet in Lakewood

Start by turning off the water at the shutoff valve behind the toilet, turning it clockwise until it stops. Flush once to drain most of the tank, and sponge out the last of the water so you can see the flapper and the valve seat clearly. If the shutoff valve will not turn, or it starts leaking when you touch it, stop. Do not force it. A seized shutoff valve can snap or start leaking badly, and replacing it is a plumber's job.

Lift the flapper and look at the rubber. If it is stiff, warped, or coated in white mineral scale, it needs replacing. Bring the old flapper with you when you buy a replacement, because flappers are not universal and the right part depends on the size and the brand. Run a finger around the flush valve seat. If it feels rough, it needs cleaning or replacing. Check the float and the refill tube, and adjust the float so the water level sits below the top of the overflow tube. Turn the water back on, let the tank fill, and listen. No trickle, no hiss, and no refill cycle after ten minutes means the fix worked.

Does a running toilet increase your water bill in Lakewood?

Yes. A running toilet is one of the most common causes of a sudden jump in a water bill, because it wastes water around the clock. A slow flapper leak can waste hundreds of gallons a day, and a stuck fill valve can waste far more. The water goes down the drain, so there is nothing to see, and the only sign is the bill. If your bill has jumped and you cannot find the source, check the toilets first with the food-coloring test. It takes ten minutes and it finds the most common culprit. If the toilets check out and the bill is still climbing, the next step is a leak check. Our leak detection page explains how a plumber finds a hidden leak, and our guide to a sudden high water bill walks through the full list of causes.

Common mistakes to avoid

• Replacing the flapper without checking the seat. A new flapper on a rough or pitted seat will not seal. Inspect the seat first.
• Buying a universal flapper without checking the fit. Flappers are not universal. Match the size and brand, or bring the old flapper to the store.
• Over-tightening the fill valve nut. Hand-tight plus a small turn is enough. Overtightening can crack the tank.
• Ignoring a silent leak because it is quiet. A silent flapper leak wastes just as much water as a noisy one. The food-coloring test catches it in ten minutes.
• Dropping a brick or a filled bottle in the tank to save water. It shifts the float and often causes the exact problem you are trying to fix.

When to call a professional

Call a plumber when you have replaced the flapper and the toilet still runs, when the tank is cracked, when the shutoff valve will not close, or when water is pooling on the floor around the base. Those are the situations where a homeowner fix turns into a bigger repair. Water pooling at the base can mean a failed wax ring or a cracked toilet, and both need professional attention. A toilet that is fifteen years or older and has needed repeated repairs may be better replaced than repaired again, and a new toilet uses less water per flush than an older one. Our fixture installation page covers toilet replacement in Lakewood homes.

For homeowners in Lakewood's older housing stock, running toilets often come with corroded flush valve seats and original fill valves that have never been replaced. Those tanks frequently need the full assembly replaced, not just the flapper, and that is a job worth doing properly the first time. If your toilet is still running after a flapper swap, or you would rather not spend your Saturday under a tank, call Emergency Plumber Lakewood at (720) 909-6690. We are open 24 hours, every day.

Get help with plumbing in Lakewood

If you would rather have a plumber take it from here, call Emergency Plumber Lakewood at (720) 909-6690. We serve homes across Lakewood, and we are open 24 hours, every day.

Questions from Lakewood homeowners

Why is my toilet running constantly in Lakewood CO?

The flapper is failing to seal in most cases. Colorado's dry air hardens rubber faster than humid climates, so flappers here often fail sooner than expected. A stuck fill valve or a float set too high causes the rest.

How do I stop my toilet from running in Lakewood Colorado?

Shut off the water, drain the tank, and check the flapper first. If it is stiff or scaled, replace it. If the flapper is fine, check the float level and the fill valve. Most fixes are a single worn part.

Does a running toilet increase my water bill in Lakewood CO?

Yes. A slow flapper leak wastes water around the clock, and a stuck fill valve can waste far more. A running toilet is one of the most common causes of a sudden jump in a water bill. Check the toilets first with the food-coloring test.

When should I call a plumber for a running toilet in Lakewood?

Call when a new flapper does not fix it, when the tank is cracked, when the shutoff valve will not close, or when water pools at the base. Those four situations need a plumber.

How can I tell if my toilet flapper is leaking?

Put a few drops of food coloring in the tank, wait ten minutes without flushing, and look at the water in the bowl. If the bowl water is tinted, the flapper is leaking.

Sources

• Denver Water — The hard truth about soft water — Denver Water hardness figures cited in this guide.
• Denver Water — Water quality reports — published water-quality data for Denver Water customers.