Short answer: A toilet usually runs because of a worn or misaligned flapper, a chain that’s too short or tangled, a float set too high, or a failing fill valve. Water keeps leaking from the tank into the bowl, so the tank keeps refilling. According to the EPA, a leaky toilet can waste about 200 gallons of water a day. Many causes are simple fixes, but if the toilet keeps running after a new flapper, or you see water on the floor, it’s time to call a plumber.
That constant trickle or random refill in the middle of the night isn’t just annoying. It shows up on your water bill, and in many Massachusetts towns sewer charges are based on water use, so you pay twice. Here’s how to find the cause and what to do about it, from the 128 Plumbing, Heating, Cooling & Electric plumbing team.
Toilet still running? 128 Plumbing, Heating, Cooling & Electric can diagnose and fix it fast, with upfront pricing before any work begins.
What Causes a Toilet to Keep Running?
| Symptom | Likely Cause | Fix |
| Water trickles into the bowl constantly | Worn, warped, or dirty flapper | Clean or replace the flapper |
| Toilet refills on its own every so often (phantom flush) | Slow flapper leak | Replace the flapper, check the flush valve seat |
| Water runs into the overflow tube | Float set too high | Lower the float so water stops about an inch below the tube |
| Running stops only when you jiggle the handle | Chain too short, too long, or tangled | Adjust the chain so it has a little slack |
| Hissing sound, tank won’t stop filling | Failing fill valve | Replace the fill valve |
| Still running after a new flapper | Corroded flush valve seat or cracked overflow tube | Professional repair or flush valve replacement |
| Water on the floor around the base | Failed wax ring or cracked tank or bowl | Call a plumber right away |
Almost every running toilet comes down to a part inside the tank that isn’t sealing or shutting off the way it should. The flapper is the most common culprit. It’s a rubber part that wears out, warps, or collects mineral buildup over time, especially with hard water.
Watch: A Running Toilet Could Be Wasting 200 Gallons a Day
Dom from our plumbing team explains why a running toilet, leaky valve, or drip is worth fixing right away.
Signs You Might Have a Silent Leak
A water bill that’s higher than usual with no change in how you use water is another sign. Toilets are one of the most common sources of hidden household leaks. For more ways to spot water waste, see our guide to detecting leaky pipes.
Water bill creeping up? We’ll find the leak and give you upfront pricing to fix it.
Quick Fixes You Can Try First
- Take the tank lid off and look. Watch what happens when you flush.
- Check the chain. It should have a little slack. Too tight and the flapper can’t seal. Too loose and it can get caught underneath.
- Check the water level. If water is spilling into the overflow tube, lower the float.
- Clean or replace the flapper. Turn off the water at the valve behind the toilet, flush to drain the tank, and swap in a matching flapper.
If none of that stops the running, or the shutoff valve behind the toilet is stuck or leaking, stop there. Forcing an old valve can cause a bigger leak.
When to Call a Plumber for a Running Toilet
- The toilet still runs after you’ve replaced the flapper
- The shutoff valve won’t turn or leaks when you touch it
- There’s water on the floor around the base
- The tank or bowl is cracked
- The toilet is old, runs often, or clogs frequently
- You also have dripping faucets or leaking valves elsewhere in the house
Our plumbers repair and replace fill valves, flush valves, shutoff valves, and complete toilets. We also fix the leaky faucets and valves that tend to show up alongside a running toilet through our plumbing service and repair and bath and kitchen fixture services. If a toilet is overflowing and won’t stop, turn off the valve behind it and call 888-CALL-128. We offer 24/7 emergency plumbing service.
Tried the quick fixes and it’s still running? Book a plumber and get it fixed right.
Repair or Replace Your Toilet?
Most running toilets just need a new part. But if yours is decades old, cracked, constantly needs repairs, or uses far more water than a modern model, replacement can make more sense. Toilets made before 1994 often use 3.5 gallons or more per flush. Federal standards now cap new toilets at 1.6 gallons, and WaterSense-labeled models use 1.28 gallons or less, which can noticeably lower your water and sewer bill.
128 Plumbing, Heating, Cooling & Electric has served Massachusetts and New Hampshire homeowners since 1992, and homeowners have made us the most reviewed home services company in New England. Read our reviews. We’ll give you an honest recommendation on repair versus replacement, with upfront pricing either way.
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Frequently Asked Questions
Why is my toilet running?
The most common causes are a worn or misaligned flapper, a chain that’s too short or tangled, a float set too high so water spills into the overflow tube, or a failing fill valve. Each one lets water keep flowing through the tank.
How much water does a running toilet waste?
According to the EPA, a leaky toilet can waste about 200 gallons of water a day. In many Massachusetts towns, sewer charges are based on water use, so a running toilet can raise both your water and sewer bills.
Why does my toilet run by itself every few minutes?
That’s often called a phantom flush. Water is slowly leaking from the tank into the bowl, usually past a worn flapper, and the fill valve turns on to top off the tank. Replacing the flapper usually fixes it.
How do I know if my toilet has a silent leak?
Add a few drops of food coloring to the tank and wait about 10 minutes without flushing. If color appears in the bowl, the flapper is leaking.
Is a running toilet an emergency?
A running toilet isn’t usually an emergency, but it wastes water around the clock and should be fixed soon. If the toilet is overflowing or leaking onto the floor, shut off the valve behind it and call 888-CALL-128. 128 Plumbing, Heating, Cooling & Electric offers 24/7 emergency plumbing service.
Should I repair or replace a running toilet?
Most running toilets just need a new flapper or fill valve. Replacement makes sense if the toilet is cracked, needs frequent repairs, or is an older high-water-use model. 128 Plumbing, Heating, Cooling & Electric will give you an honest recommendation with upfront pricing.
Stop Paying for Water You’re Not Using
128 Plumbing, Heating, Cooling & Electric has served Massachusetts and New Hampshire homeowners since 1992, and homeowners across the region have made us the most reviewed home services company in New England. Our licensed plumbers fix running toilets, leaky valves, and drips fast, with upfront pricing before any work begins.
