Why does my toilet keep running?
The tank refills on its own every few minutes, or you hear a constant trickle into the bowl between uses.
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Key takeaways
- This is usually not an emergency, but it does not fix itself and it gets worse if you leave it.
- Most likely cause: Worn or warped flapper.
- Do this first: Put a few drops of food coloring in the tank and wait twenty minutes. Color in the bowl proves a flapper leak.
- Call right away if water is spilling out of the tank onto the floor.
- The repair starts with: Dye test to confirm the leak path.
What it is
Constantly running toilet A constantly running toilet means water is continuously leaking from the tank into the bowl, almost always because the flapper is not sealing or the fill valve is misadjusted.
It wastes water around the clock, so it should be fixed as soon as you notice it even though it is not an emergency.
The short answer
A toilet that runs constantly is nearly always a flapper problem. The rubber flapper has warped or scaled so it no longer seals, water leaks into the bowl, and the fill valve keeps topping the tank off. The other common causes are a fill valve set too high, so water spills into the overflow tube, and a chain that is too short to let the flapper drop. A running toilet is not an emergency, but it can add thousands of gallons to a quarterly bill.
What it usually means
These are the causes we find most often, ranked from most likely to least.
- 1
Worn or warped flapper
Most likely
Hard water and age stiffen the rubber so it stops sealing against the flush valve seat.
- 2
Water level set above the overflow tube
Common
Water pours down the overflow continuously and the fill valve never shuts off.
- 3
Chain length wrong
Common
A short chain holds the flapper open, a long one tangles under it.
- 4
Failed fill valve
Less common
The valve no longer closes fully, so the tank never reaches a stable level.
- 5
Cracked or scaled flush valve seat
Occasional
Even a new flapper will not seal against a damaged seat, so the whole valve gets replaced.
What to do right now
- 1Put a few drops of food coloring in the tank and wait twenty minutes. Color in the bowl proves a flapper leak.
- 2Set the water level about one inch below the top of the overflow tube.
- 3Adjust the chain so it has a small amount of slack when the flapper is closed.
- 4Shut the supply stop behind the toilet if you need to stop the waste immediately.
When it is an emergency
- Water is spilling out of the tank onto the floor.
- The toilet runs and the bowl level is also rising, which points to a drain problem as well.
What the fix involves
Most running toilets are solved by replacing the flapper and adjusting the fill valve. Where the flush valve seat is damaged or the tank hardware is old, the whole flush and fill assembly is replaced so the parts match and seal properly.
- 1Dye test to confirm the leak path.
- 2Replace the flapper and set the correct water level.
- 3Replace the fill valve if it will not shut off cleanly.
- 4Replace the full flush valve assembly where the seat is damaged.
What drives the cost
Every job is quoted before work begins. These are the factors that move the number on this kind of repair.
- Single part replacement versus full tank rebuild
- Toilet age and whether matching parts are available
- Number of toilets serviced in the same visit
Related problems homeowners ask about
Why won't my toilet flush?
The handle moves with no result, the bowl rises and drains slowly, or the flush is weak and leaves waste behind.
Read this nextWhy did my water bill suddenly go up?
A bill well above the seasonal norm with no change in usage, sometimes with a warm floor spot, a damp yard, or the sound of running water.
Read this nextWhy are my pipes whistling?
A high pitched whistle or squeal when water runs, sometimes only at partial flow or only when a toilet refills.
Read this next
Read more on this
This page is for triage and dispatch. These guides go deeper on how the work is done and what shapes the price.
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- Colorado Master PlumberLicense MP-18927
- Colorado State Plumbing ContractorLicense 2110
- Family Owned & OperatedServing Denver since 2006, 20 years
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- Angie's List Super Service Award2012 through 2017
- Serving Denver since 2006Residential and commercial properties across the metro
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Before you book: pricing, timing, and guarantees
Straight answers on what toilet running constantly work costs, how fast we can get out, and what stands behind the repair.
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