Short Answer
A toilet keeps running because water is escaping the tank one of two ways: over the top of the overflow tube, or past the flapper and flush valve into the bowl. Find which path it is taking, then fix that part. In Houston, Repipe Solutions repairs running toilets for $125 to $350, parts and labor.
When a toilet keeps running, the hiss does not stop after the tank refills, or it stops only when someone jiggles the handle. Repipe Solutions is a licensed Houston plumbing company, and a running toilet is our most common toilet call. This guide shows how to find the failed part before you buy anything, how to fix it, and when to call a plumber.
Why Does My Toilet Keep Running?
American Standard traces a running toilet to four parts: the flapper or seal, the flush valve, the fill valve, and the trip lever. Korky says the flapper or flush valve seal is the cause more often than not. Two more causes are settings rather than broken parts: a chain at the wrong length and a water level set too high. The fastest way to sort them out is to watch where the water goes.
Toilet Won’t Stop Running? First, Find Where the Water Is Going
Lift the tank lid and set it flat on a towel, since it is heavy porcelain and cracks if it tips. Flush, let the tank refill, and look at the open tube in the middle of the tank.
- Water is spilling into the top of the overflow tube. The tank is overfilling: check the water level setting and the fill valve.
- The water sits below the overflow, but you still hear running. Water is leaking past the flapper or flush valve into the bowl.
To confirm, lift the float by hand while it runs. If the water stops, the problem is on the fill side. If jiggling the handle stops it, start with the chain and trip lever.
The Pencil Mark Test: Which Part Is Leaking
When water is leaking into the bowl, this test tells you which part has failed.
- Let the tank fill completely. Do not flush.
- Turn the supply valve behind the toilet clockwise until it stops. If it will not turn, do not force it. Corroded supply stops are common in Houston, and a forced one can break.
- Draw a pencil line on the inside of the tank at the water line.
- Wait. Fluidmaster says to wait 30 minutes, mark again, and keep checking until the level stops dropping. Korky says to wait at least 25 minutes.
The water drains down to the leak, then holds. Where it stops tells you which part failed.
| Where the water stops | What it means | The fix |
|---|---|---|
| Does not drop at all | Nothing is leaking into the bowl. The fill valve is overfilling. | Lower the water level, flush out the fill valve, or replace it |
| Drops 1/4 to 1/2 inch, then stops | Refill tube is siphoning, or the overflow tube is cracked | Reposition the refill tube, or replace the flush valve |
| Drops to the top of the flapper | Worn flapper or a rough valve seat | Clean the seat, replace the flapper |
| Drops to the bottom of the tank | The flush valve or the gasket under it has failed | Replace the flush valve (the tank comes off the bowl) |
That table follows the results described by Fluidmaster and American Standard. It prevents the most common wasted purchase: a new flapper on a toilet whose real problem is the flush valve.
How to Fix a Toilet That Keeps Running, Part by Part
Work through these in order. The first two cost nothing. Shut off the supply valve before removing any part.
1. Set the water level
The Fluidmaster fill valve instructions set the water level below the top of the overflow tube and recommend 1/2 inch below. On a modern float cup valve, turn the adjustment rod or screw to lower the cup. Flush and check where the water settles.
While you are there, look for the “CL” (critical level) mark printed on the fill valve. Fluidmaster’s instructions say that mark must sit 1 inch above the top of the overflow tube, calling it a plumbing code requirement that helps protect your drinking water supply. If the mark sits below the overflow, the valve was installed too low and should be reset or replaced.
2. Fix the chain and handle
Chain guidance varies by maker: Fluidmaster’s instructions say to leave 1/2 inch of slack, Kohler says one to two links, and American Standard says some Champion models want the chain taut with no slack. The test is the same: the flapper should lift right away when you press the handle and close fully when you let go. A chain too long can fall under the flapper; too short holds it open. American Standard notes a bent or worn trip lever can also hold the flapper open and should be replaced.
3. Flush out or replace the fill valve
If the level test showed no drop and the water still rises into the overflow, the fill valve is not shutting off. Kohler says this is often caused by sediment lodged in the valve cap, especially after a new installation. Fluidmaster’s fix is to remove the valve cap, hold a cup upside down over the open valve, and briefly turn the water on to flush debris out. If it still runs, replace the fill valve, and hand tighten the locknut only. Fluidmaster warns that overtightening can crack the valve or tank and cause flooding.
4. Check the refill tube
The small tube from the fill valve should clip to the overflow tube and spray into it from above the water. Fluidmaster’s instructions warn not to push it down inside the overflow, because it can siphon water out of the tank and cause significant waste.
5. Replace the flush valve
If the water drained to the bottom of the tank, or a new flapper did not stop the leak, the flush valve is the part. A cracked overflow tube is part of the same assembly. On a two-piece toilet the tank comes off the bowl and the tank-to-bowl gasket is replaced too. This is the one running toilet repair we suggest handing to a plumber, because an overtightened bolt can crack porcelain.
Toilet Flapper Leaking? Make Sure It Is the Right One
Replacing a flapper is a ten minute job, but flappers are not universal. Fluidmaster explains how to size one: measure your old flapper across. A flapper about 3 inches wide fits a 2 inch flush valve, and one about 4 inches wide fits a 3 inch valve. Kohler canister valves and American Standard Champion towers take their own seals, not a standard flapper.
Fluidmaster advises wiping slime and debris off the seat and the underside of the flapper, and simply replacing any flapper more than 5 years old. In Houston, chlorinated city water is hard on rubber, and we often see flappers fail in 3 to 5 years.
Toilet Keeps Running After Flush but Stops on Its Own
A toilet that runs for several minutes after each flush, then stops, usually has a water level set just high enough to spill over the overflow for a while, or a chain that snags as the flapper closes. Kohler describes this case: if water spills into the overflow but eventually stops, the tank water level needs adjusting. If instead the toilet starts refilling by itself with nobody touching it, that is a separate pattern covered in our guide to why a toilet flushes on its own.
What a Running Toilet Wastes
The EPA has said that replacing a worn flapper could save a home up to 200 gallons of water per day. The EPA’s WaterSense Fix a Leak Week page adds that the average household’s leaks waste more than 9,300 gallons a year, and that fixing easy household leaks can save about 10 percent on water bills.
In the City of Houston, the bill hits twice, since sewer charges are based on the water you use. Left alone for a month, a toilet that never stops running can add $60 to $100 or more to the combined bill.
How Much It Costs to Stop a Toilet From Running in Houston
These are Repipe Solutions’ Greater Houston price ranges, parts and labor included. Every job gets an exact written quote first, with no trip charge.
| Repair | Typical Houston price |
|---|---|
| New flapper or flush valve seal | $95 to $175 |
| New fill valve | $125 to $250 |
| New flush valve (tank removed) | $175 to $350 |
| Most running toilet fixes | $125 to $350 |
If the toilet is old, the porcelain is cracked, or you keep replacing tank parts, read whether to rebuild or replace your toilet before spending more on parts.
When to Call a Plumber
- The pencil mark test shows water draining to the bottom of the tank, or the overflow tube is cracked. That is a flush valve replacement with the tank off.
- You replaced the flapper and the toilet still runs.
- The supply valve behind the toilet is seized, leaks, or will not fully close.
- There is water on the floor. Fluidmaster says to turn the water off right away and check whether it is coming from the lid or tank lever area. Water at the base is a different problem, explained in our guide to a leaking toilet.
- Two DIY attempts have not fixed it. The real issue is usually one layer down.
Our toilet repair team in Houston tests the flapper and fill valve, dye tests for silent leaks, and quotes the fix before any work starts.
Frequently Asked Questions
Is a running toilet an emergency?
Usually not. The extra water goes down the drain, not onto the floor, but it wastes water every hour. If water is on the floor, shut off the supply valve and treat it as urgent.
Should I shut off the water to a running toilet until it is fixed?
Yes, if you cannot fix it the same day. Close the valve behind the toilet, open it to refill the tank before each use, then close it again. Do not force a stiff valve.
Why does jiggling the handle make the running stop?
Jiggling lets a flapper that did not drop fully settle back onto its seat. The chain is the wrong length, the trip lever is sticking, or the flapper is warped. Adjust the chain first.
Does a universal flapper fit every toilet?
No. Flappers come in 2 inch and 3 inch sizes, and some toilets use canister or tower seals instead of a flapper. Take the old one to the store. The wrong size will keep leaking.
Are bleach tablets in the tank bad for my toilet?
They can be. Fluidmaster warns that drop-in cleaners containing bleach or chlorine damage tank parts and can lead to flooding, and Kohler says in-tank cleaners wear down flappers and canister seals. Clean the bowl instead.
Can a running toilet overflow onto the floor?
Not from a tank that is overfilling, because the overflow tube sends the extra water into the bowl. A running toilet can overflow if the bowl drain is also clogged. If the bowl is rising, stop flushing and see our guide to a clogged toilet.
Toilet Still Running? Get It Fixed
Repipe Solutions fixes running toilets across Greater Houston with free quotes, no trip charge, and same-day service available. See our toilet repair and installation services in Houston or contact Repipe Solutions to schedule a visit.
Featured photo: “Inside a toilet tank” by brtinney via Openverse, licensed under CC BY 2.0, converted to WebP.