Toilet Keeps Running? Here's What's Causing It
- Admiral Plumbing Heating & Cooling
- 2 days ago
- 5 min read
That sound of water constantly trickling in your bathroom is hard to ignore. If your toilet keeps running long after you flush, something inside the tank is not working right. The good news is that a running toilet is one of the most common plumbing problems. And in many cases, the fix is simple.
In this post, we will walk you through the most likely causes of a running toilet. We will also explain when you can handle it yourself and when it is time to call a plumber.
Why Is My Toilet Running?
A toilet running constantly wastes a surprising amount of water. In fact, a leaking toilet can waste up to 200 gallons of water per day. That adds up fast on your water bill.
Most of the time, the problem comes down to a few key parts inside the toilet tank. Let us look at each one.
The Most Common Causes of a Running Toilet
1. A Worn or Faulty Toilet Flapper
The flapper is the rubber seal at the bottom of your toilet tank. When you flush, it lifts to let water flow into the toilet bowl. Then it drops back down to seal the tank so it can refill.
Over time, the flapper can warp, crack, or wear out. When that happens, it does not seal properly. Water slowly leaks from the tank into the toilet bowl. This keeps the fill valve running to keep up with the loss.
Toilet flapper replacement is one of the easiest DIY fixes. A new flapper costs just a few dollars at any hardware store. You simply turn off the water supply, unhook the old flapper, and snap on the new one.
Not sure if the flapper is the problem? Try this simple test. Put a few drops of food coloring into the tank.
Wait 15 minutes without flushing. If color shows up in the bowl, your flapper is leaking.
2. The Float Is Set Too High
The float is a ball or cup inside the tank that rises with the water level. When it reaches a set height, it signals the fill valve to stop adding water.
If the float is set too high, water keeps rising past the fill line. It then overflows into the overflow tube and drains into the bowl. This causes your toilet tank to keep running.
You can check this by lifting the lid off your tank. If water is spilling into the overflow tube, the float needs to be adjusted. Most floats can be bent down slightly or adjusted with a screw. The water level should sit about one inch below the top of the overflow tube.
3. A Faulty Fill Valve
The fill valve controls how water enters the toilet tank after a flush. When it starts to wear out, it may not shut off completely. This causes the toilet tank running sound you hear long after the bowl has refilled.
A bad fill valve can cause a hissing or trickling sound even after the tank appears full. This is a common cause of toilet flushing problems and toilet leaking water.
Replacing the fill valve is a moderate DIY task. But if you are not confident working with the water line connections, it is a good idea to call a professional.
4. A Damaged Overflow Tube
The overflow tube is a vertical pipe inside the tank. It acts as a safety drain to prevent the tank from overflowing onto the floor. If this tube cracks or is cut too short, water may constantly drain into the bowl.
In most cases, the overflow tube needs to be replaced. This is a straightforward repair, but it does require draining the tank and disconnecting some parts.
Toilet Keeps Running After Flushing: What’s Going On?
A toilet running after flush that stops on its own is usually a sign of a slow flapper or a fill valve that takes too long to close. This is sometimes called a ghost flush because the toilet seems to flush on its own out of nowhere.
Ghost flushing happens when a small amount of water slowly escapes the tank. Once enough water is lost, the fill valve kicks on to refill. It looks like the toilet is flushing by itself.
Again, this usually points back to the flapper. It is worth starting there before replacing any other parts.
Can I Fix a Running Toilet Myself?
Many running toilet fix solutions are beginner-friendly.
Toilet flapper replacement
Adjusting the float
Minor fill valve adjustments
These usually take 15–30 minutes and require basic tools.
Call a pro if:
The fill valve needs full replacement
The overflow tube is damaged
You see toilet leaking water around the base
The problem keeps coming back
Ignoring a toilet running constantly can lead to higher bills and bigger toilet repair issues down the line.
When to Call a Toilet Repair Service
Some toilet problems look simple but turn out to be more complex. Here are signs it is time to stop guessing and call a toilet repair service.
You should call a plumber if your toilet is more than 10 to 15 years old and parts keep wearing out. Old toilets often have corroded parts that are harder to replace. A plumber can assess whether repair or replacement makes more sense.
You should also call if you see water pooling around the base of the toilet. This could point to a broken wax ring or a cracked base, which goes beyond a simple running toilet fix.
The wax ring creates a watertight seal between the toilet and the drainpipe in your floor. When it fails, water seeps out at the base and can damage your floor and subfloor if left untreated.
Finally, if you have replaced the flapper and adjusted the float but the toilet is still running, there may be a deeper issue with the fill valve or the overall toilet repair is beyond a quick part swap.
Quick Summary: Most Likely Causes at a Glance
A worn flapper causes a slow leak from the tank into the bowl. A high float setting sends water into the overflow tube. A faulty fill valve fails to shut off after the tank fills. A damaged overflow tube drains water straight to the bowl.
Still Hearing That Running Sound? Admiral Plumbing Can Help.
You now know the most common reasons a toilet keeps running and which fixes you can try on your own. But if the problem persists or you are dealing with something more serious like water damage or an aging toilet, do not wait it out.
At Admiral Plumbing, we handle everything from simple toilet repair to full plumbing system assessments. Our licensed plumbers are experienced, honest, and ready to help you stop wasting water and money.
Whether you need a quick running toilet fix or a full plumbing toilet repair service, we are here to get the job done right.
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