A running toilet isn’t just an annoyance—it can waste up to 200 gallons of water per day, adding $70–$100 per month to your water bill. The good news? Most running toilets can be fixed in less than 30 minutes with a $10–$25 replacement part and basic tools.
In most cases, the issue comes down to a worn-out flapper, a misaligned float, or a faulty fill valve—all of which are easy to diagnose and fix. Ignoring the problem can lead to hidden leaks, water damage, and higher utility costs.
This guide will walk you through step-by-step solutions to stop your toilet from running, save money on water bills, and avoid unnecessary plumbing calls.
Parts of the Toilet
Before fixing a running toilet, you need to know which part is causing the issue. The problem usually comes down to one of three components: the flapper, the float, or the fill valve.
Flapper – This rubber seal at the bottom of the tank lifts when you flush, letting water flow into the bowl. If it’s worn or warped, water will leak continuously, forcing the fill valve to keep running. Solution: Replace the flapper (a quick and inexpensive fix).
Float – This buoyant piece controls water levels by signaling the fill valve to stop refilling. If you set it too high, the tank overfills, and water constantly runs into the overflow tube. Solution: Adjust the float to the correct level.
Fill Valve – This controls water flow into the tank. If it’s worn out, it won’t shut off properly, leading to constant refilling. If adjustments don’t work, replace the fill valve.
Most running toilet issues come down to one of these three parts—and fixing them can save you hundreds of dollars in water waste.
Identify the Cause of the Problem
To fix a running toilet, first diagnose the problem with these simple steps:
- Listen for Running Water – If you hear water running constantly, the issue is likely the flapper, float, or fill valve.
- Check for Leaks – Look around the base of the toilet, water supply line, and tank. If you see pooling water, tighten any loose connections or replace worn seals.
- Inspect the Water Level – Open the tank lid. If the water overflows into the tube, the float is too high. Adjust it down to stop excess refilling.
- Test the Flapper Seal – Push down on the flapper. If the water stops running, it’s worn out and needs replacing. If it’s dirty, clean the valve seat to improve the seal.
- Check the Fill Valve – If the water keeps running even after adjusting the float and replacing the flapper, the fill valve is likely faulty and needs replacement.
By following these steps, you can quickly pinpoint the issue and avoid wasting gallons of water daily.
Adjust the Float
If the float is too high, your toilet overfills and runs nonstop. If it’s too low, your toilet won’t flush properly. Here’s how to adjust it:
Steps to Adjust the Float:
- Turn off the water – Locate the shut-off valve behind the toilet and turn it clockwise.
- Remove the tank lid – Set it aside carefully.
- Find the float type:
- Ball Float (this type attaches to a metal rod) – Bend the rod downward to lower the water level or upward to raise it.
- Cup-Style Float (this type slides along the fill valve) – Pinch the clip or turn the adjustment screw to change the height.
- Test the water level – Flush and let the tank refill. The water should stop about 1 inch below the overflow tube.
- Fine-tune if needed – Adjust again if the water level isn’t correct.
- Turn the water back on – Open the shut-off valve counterclockwise and check for proper function.
A simple float adjustment can stop your toilet from running and prevent water waste. If adjustments don’t work, you may need to replace the fill valve.
Replace a Running Toilet’s Tank Flapper
A worn-out flapper is the most common cause of a running toilet. If it’s warped, cracked, or doesn’t seal properly, water continuously leaks into the bowl, triggering the fill valve to keep running. Replacing it takes just a few minutes.
How To Replace a Toilet Flapper:
- Turn off the water – Locate the shut-off valve near the toilet’s base and turn it clockwise.
- Drain the tank – Flush the toilet and soak up any leftover water with a sponge or towel.
- Remove the old flapper – Unhook the chain from the flush lever and detach the flapper from the flush valve. Check its size and shape before buying a replacement.
- Install the new flapper – Attach it to the flush valve and reconnect the chain. Make sure there’s slight slack—too tight, and it won’t seal; too loose, and it won’t lift properly.
- Turn the water back on – Open the shut-off valve and let the tank fill.
- Test the flush – Flush a few times to ensure the flapper seals correctly and stops the water from running.
Replacing a flapper is one of the easiest and cheapest ways to fix a running toilet. If the problem persists, the issue may be with the fill valve instead.
Watch: How to Replace a Toilet Flapper Valve
There are many products out there that make flapper replacement easy. For instance, Fluidmaster’s 502 PerforMAX Water-Saving, Adjustable Flapper offers a customized flush. To use it, you just have to turn the dial left for more water per flush, or right for less, depending on your needs.
Adjust the Fill Valve
The fill valve is the mechanism that refills the tank after a flush. If water is constantly running into the overflow tube in the toilet tank, you need to adjust the fill valve in the tank.
Steps to Adjust the Fill Valve:
- Turn the water supply back on – Turn the shut-off valve counterclockwise to restore the water supply.
- Turn off the water supply – Locate the shut-off valve behind the toilet and turn it clockwise to shut off the water supply.
- Remove the tank lid – Lift the tank lid off the tank and set it aside.
- Check the water level – The water level in the tank should be about one inch below the top of the overflow tube. If it’s higher than that, the fill valve may be improperly adjusted.
- Locate the adjustment screw – The adjustment screw is usually located on top of the fill valve. It’s a small screw that can be turned with a flathead screwdriver.
- Adjust the fill valve – To lower the water level, turn the adjustment screw counterclockwise. To raise the water level, turn the screw clockwise. Turn the screw a quarter turn at a time and check the water level each time until it’s at the correct level.
- Test the toilet – Flush the toilet and let it fill. The water level in the tank should stop just below the top of the overflow tube. If it doesn’t, adjust the fill valve again until the water level is correct.
Diagnosing a Faulty Fill Valve
If your toilet keeps running even after adjusting the float or replacing the flapper, the fill valve may be worn out.
How To Check for a Faulty Fill Valve:
- Check the water level – Open the tank lid. If the water overflows into the tube or is too low for a proper flush, the fill valve may not be working correctly.
- Listen for running water – If you hear a constant hissing or trickling sound, the fill valve isn’t shutting off properly.
- Manually lift the float – If lifting the float doesn’t stop the water flow, the fill valve needs replacing.
Replacing a fill valve takes about 30–60 minutes with basic tools, but if you’re unsure, a plumber can handle it quickly.
Additional Tips
Preventing a running toilet saves you money, avoids water waste, and reduces the risk of costly repairs. Here’s how to keep your toilet in top shape:
- Check for Leaks Regularly – Lift the tank lid every few months to inspect the flapper, fill valve, and water level. Catching small issues early prevents bigger problems.
- Flush Smart – Only flush toilet paper and waste. Items like wipes, paper towels, and hygiene products can clog the system and damage components.
- Ditch Harsh Cleaners – Chemical cleaners wear down rubber parts like the flapper. Instead, use vinegar and baking soda to clean the tank and bowl safely.
- Replace Worn Parts Before They Fail – If your flapper, fill valve, or float looks worn or brittle, swap it out before it causes a constant leak.
- Teach Proper Use – Make sure everyone in your household knows what shouldn’t go down the toilet to prevent unnecessary damage.
Pro Tip: If your toilet is more than 20 years old, consider replacing it with a water-efficient model that uses less than half the water per flush.
If you really want to save money on your water bill you should probably consider replacing your old toilet with a new one. Some older toilets use as much as 3.5 gallons of water per flush. Nowadays, the law requires newer models to operate with a maximum of 1.6 gallons.
Watch the video at the beginning of the article to learn more. Or, click on your state below to find local plumbing experts:
