That hissing or trickling sound from your bathroom is easy to get used to. But if your toilet keeps running after every flush, or cycles on randomly even when no one is using it, it is costing you money every single day.
A running toilet can waste up to 200 gallons of water per day. Over a month, that adds up to more than 6,000 gallons. Over a full year, you could be looking at 70,000 gallons or more of water you paid for and never used. In Northshore communities like Covington, Mandeville, and Slidell, that translates to an extra $20 to $70 or more on your monthly water bill depending on the severity of the leak and your local water rate.
The good news is that a running toilet is usually one of the more straightforward plumbing problems to diagnose and fix. Here is what causes it, what it is costing you, and when it makes sense to call a professional.
How a Toilet Is Supposed to Work
Understanding why a toilet runs starts with knowing what it is designed to do.
When you flush, water in the tank rushes into the bowl through the flush valve, which is controlled by the flapper at the bottom of the tank. The tank then empties and a float drops, triggering the fill valve to bring fresh water in. As the tank refills, the float rises. Once the water reaches the correct level, the fill valve shuts off and the flapper reseats itself, sealing the tank until the next flush.
When any part of this sequence breaks down, water keeps moving when it should be stopped. That constant movement is what you are hearing.
The Most Common Causes of a Running Toilet
A Worn or Damaged Flapper
The flapper is the rubber seal at the bottom of the tank. It lifts when you flush and drops back into place to stop water from flowing into the bowl between flushes. Over time, rubber flappers degrade, warp, or accumulate mineral deposits that prevent a proper seal. When water leaks past a bad flapper, the fill valve runs continuously to compensate.
This is the most common cause of a running toilet and usually the easiest fix. A replacement flapper costs a few dollars at any hardware store and takes about 10 minutes to swap out.
A Float Set Too High
The float is what tells the fill valve to shut off once the tank is full. If the float is adjusted too high, the water level rises above the overflow tube and drains continuously into the bowl, keeping the fill valve running without ever satisfying the shutoff.
You can usually spot this by looking inside the tank while it is running. If water is spilling over the top of the overflow tube, the float needs to be adjusted downward. On newer fill valve assemblies, there is typically a clip or adjustment screw that changes the shutoff level without tools.
A Failing Fill Valve
If the fill valve itself is worn out, it may not shut off completely even when the float is in the correct position. A persistent hissing sound that continues even when the water level appears correct is often the sign of a failing fill valve. Fill valve replacement is a straightforward repair but does require turning off the water supply and draining the tank.
A Chain That Is Tangled or the Wrong Length
The chain connecting the flush handle to the flapper needs just a small amount of slack. Too short and it holds the flapper partially open, allowing water to trickle through constantly. Too long and it can get caught under the flapper and break the seal. Adjusting chain length is one of the quickest fixes in residential plumbing.
An Overflow Tube That Is Too Short
If the overflow tube inside the tank is too short for the fill valve’s default shutoff level, water drains into the bowl continuously even at the normal fill height. This usually means the flush valve assembly needs to be replaced.
How Much Is a Running Toilet Costing You?
A moderate running toilet leak wastes approximately 6,000 gallons per month. At typical water rates across the Northshore, that adds somewhere between $20 and $70 to your monthly utility bill, sometimes more depending on how severe the leak is and whether your sewer charges are calculated based on water usage.
Over a full year, you could be paying $240 to $840 or more for water that served no purpose. The repair cost is almost always a fraction of that. A DIY flapper replacement runs $5 to $15 in parts. A professional repair typically costs $150 to $300 and is recovered in water savings within the first year.
How to Check If Your Toilet Is Leaking Silently
Some toilets run so slowly that you cannot hear them but are still wasting water. The food coloring test identifies a silent leak in minutes.
Remove the tank lid and add several drops of food coloring into the tank water. Wait 15 minutes without flushing. Then check the bowl. If color has appeared in the bowl, water is leaking past the flapper even without a sound.
How to Fix a Toilet That Keeps Running: Can You Fix It Yourself?
For a worn flapper or a simple float adjustment, yes. If you are comfortable turning off the water supply valve behind the toilet, draining the tank, and following the instructions that come with replacement parts, these are manageable DIY repairs.
Call a plumber when:
- You have tried the simple fixes and the toilet is still running
- The issue is not apparent after checking the flapper, chain, and float
- You hear hissing but the water level looks correct
- The toilet is old and multiple tank components appear worn or corroded
- There is water around the base of the toilet or signs of a leak below the tank
Our bathroom plumbing team handles toilet repairs throughout the Northshore and can diagnose and fix most running toilet issues in a single visit.
When to Replace Instead of Repair
If your toilet is more than 20 years old and has needed repairs before, replacement may make more sense than continued service. Older toilets use 3.5 to 6 gallons per flush compared to 1.28 gallons or less for modern high-efficiency models. The water savings from switching are meaningful over time, especially for a household that uses the bathroom frequently.
If you are already working with our team on a bathroom plumbing repair, ask whether your current toilet is worth keeping based on its age and condition.
Other Reasons Your Water Bill Might Be High
If you fix the running toilet and your water bill stays elevated, other issues may be contributing. Common culprits include:
- Dripping faucets or shower fixtures
- A slab leak or a hidden supply line leak inside the wall or under the foundation
- A water softener cycling incorrectly
- An irrigation system leak
Our leak detection service can identify hidden water loss anywhere in your home’s plumbing system, including locations that are impossible to spot without specialized equipment.
Ready to Get Your Toilet Fixed on the Northshore?
Southern Air has been serving the Northshore since 1984. Our licensed plumbers offer upfront pricing before any work begins and same-day service in most cases. Whether you need a quick flapper swap or a full toilet replacement, we will tell you exactly what the problem is and what it will cost before we touch anything.
Call us at (985) 200-5442 or schedule online to book a plumbing visit today.
