Toilet Repair & Installation
Stop a toilet from running, leaking or clogging, or set a new one.
Homeowner guide
Running Toilet Fix in Commerce City, CO: Step by Step
A toilet that runs by itself nearly always has a leaking flapper or a fill valve set too high. Both fixes are quick, and the savings show on your next water bill.
By the Mile High Express Plumbing team · published
Why a running toilet matters
A toilet that runs steadily can waste hundreds of gallons in a month, and you may never hear it. A quiet leak from the tank into the bowl drains slowly and refills the tank every few minutes.
This is a common reason for a high water bill, and fixing it costs little.
The food coloring test
Remove the tank lid and add a few drops of food coloring without flushing. After about a quarter hour, check the bowl. If the bowl water shows color, the flapper is leaking.
If no color appears but the toilet still runs, look at the fill valve and the overflow tube.
Replace the flapper
Close the shutoff valve, flush to empty the tank and unhook the old flapper from the overflow tube ears and chain. Match the new flapper to the flush valve size, usually 2 or 3 inches. Attach it and adjust the chain so that it has a little slack.
Open the valve and test. A flapper that fits right seats quietly after each flush.
Adjust the fill valve and float
Water dribbling into the overflow tube means the level is too high. Lower the float with the adjustment screw or by sliding the clip, so the water stops roughly an inch under the top of the tube.
A fill valve that hisses and never shuts off may be worn. Replacement kits install in minutes with simple tools.
What each running-toilet symptom points to
Find your symptom and swap the matching part.
| Symptom | Probable cause | Repair |
|---|---|---|
| Refills every few minutes | Leaking flapper | Install a new flapper |
| Water spills into the overflow tube | Float riding too high | Lower the float |
| Constant hiss | Worn fill valve | Replace the fill valve |
| Flapper hangs open | Chain too short | Lengthen the chain |
Chain trouble
A chain that is too short holds the flapper open. One that is too long can get caught under it. Leave about half an inch of slack.
If the handle is sticking, free the lever or replace the handle.
When it keeps running
With a new flapper and fill valve and the toilet still running, the flush valve seat may be pitted or corroded. Replacing the flush valve, or the whole toilet, solves it.
A toilet repair visit handles these quickly.
Check the supply valve
The shutoff valve behind the toilet can leak at the stem or refuse to close. Replace it if it will not shut. A reliable valve lets you stop the water in any emergency.
Replace the braided supply line if it is old.
Savings and next steps
After a repair, watch the meter with all fixtures off to confirm that water use has dropped. If it still moves, another leak exists, and leak detection can find it.
If you want to confirm the fix, repeat the food coloring test after a day.
Tools and parts
Most running-toilet repairs call for an adjustable wrench, a sponge for the tank water that is left and one replacement part. Universal flappers and fill valves suit many toilets, though some models need an exact match, so carry the brand name from the tank or bowl rim to the store.
Replacement kits include clear instructions. Most take less than half an hour, and you can test the result right away. Buy a spare flapper for the next time.
Reading the sound and the water level
Listen at the tank. A hiss means the fill valve is open and water is escaping somewhere. A dribble into the overflow tube means the level is set too high. A phantom flush every few minutes means the flapper is leaking.
Look for a fill line marked inside the tank. Water above it means the float needs adjusting, with the goal an inch under the top of the overflow tube.
Dual flush and older toilets
Dual flush valves have a different flapper or a canister seal, and a worn seal causes the same slow leak. Check the maker's instructions for the right replacement. Older toilets with a ball float and a rubber tank ball need a ball and a guide rod that line up.
If the parts are no longer available, a toilet replacement can be the cheaper path. A modern toilet also uses less water per flush than one made decades ago.
Mineral buildup on the parts
Scale builds up on the flapper seat and the fill valve in the tank. A rough seat stops a new flapper from sealing, even when the flapper is fine. Wipe the seat with a cloth or a nonmetallic scouring pad until it is smooth.
If the seat is pitted, a flapper repair ring can glue over it. Otherwise the flush valve needs replacement, which also requires removing the tank.
A simple monthly habit
Once a month, lift the tank lid and look. A tank water level that is steady, a flapper that sits flat and a chain with a little slack mean the toilet is healthy. Press down on the flapper to see whether it feels soft or stiff.
Catching a worn part early takes five minutes and prevents the sound, the waste and the surprise on the bill.
Replacing the whole fill valve
Shut off the supply, flush and sponge out the tank. Unscrew the supply line and the locknut under the tank, lift out the old valve and insert the new one at the same height. Tighten by hand plus a quarter turn and connect the refill tube to the overflow tube.
Turn the supply back on gradually and adjust the float so the water settles an inch short of the top of the overflow tube. Flush a few times and inspect each connection for drips.
Common questions
Running toilet questions
A steady run can waste hundreds of gallons a month.
Many last several years. Mineral film and rubber hardening shorten that.
A slow leak from tank to bowl lowers the water until the fill valve cycles.
Usually yes. Flappers and fill valves are simple parts, and a plumber can help if it is stubborn.
Services that help
Leak Detection
Pinpoint a hidden leak using acoustic listening, thermal imaging and pressure tests.
Faucet & Sink Repair
Cure drips, weak streams, stuck stops and dripping outdoor taps.
Keep reading
Toilet won't flush
A toilet that will not flush is usually a clog or a tank problem. Here is how to tell which and what to try first.
Why your water bill is high
A bill that jumps usually has a findable cause. Check the meter first, then the toilets.
How to find a water leak
A meter, a few paper towels and a systematic walk-through can find most leaks before they cause damage.
Toilet still running?
Phone in and tell us what the toilet is doing. A local contractor will be arranged.