Toilet Repair & Installation
Repair a toilet that runs, rocks, flushes weakly or overflows, or swap in a new one. Open page
Plain-English article
Fixing a Running Toilet in Thornton, CO: A Practical Guide
A toilet that runs after a flush, or refills on its own, wastes water and money. The cause is nearly always in the tank, and the parts are cheap.
By the Thornton Plumbing Co. team ·
Find out where the water is going
Lift off the tank lid and stir in some food coloring. Wait fifteen minutes without flushing. If the color shows in the bowl, water is slipping past the flapper.
When water rises over the top of the overflow pipe, the fill valve is failing to close. If the water is below, the flapper is probably fine, and the fill valve may be set too low.
Replace the flapper
Turn off the supply valve and flush to empty the tank. Unhook the old flapper, take it to a store and buy a match. Hook the new one to the overflow tube pegs and attach the chain with a little slack.
Mineral deposits on the flush valve seat can also leak. Wipe the seat with a cloth to clean it.
Parts and what they fix
These three parts cause nearly every running toilet.
| Part | Symptom | Fix |
|---|---|---|
| Flapper | Color shows in the bowl | Replace and clean the seat |
| Chain | Flapper held open | Adjust slack to about half an inch |
| Fill valve | Water keeps rising or hissing | Replace and set the float |
Adjust the chain
The chain should have about half an inch of slack when the flapper is closed. Too much slack lets it tangle, and too little holds the flapper open. Clip off extra chain if it dangles.
Check that the lift arm moves freely. A bent arm or a loose handle can stop the flapper from closing.
Replace the fill valve
If the water keeps rising or hissing, replace the fill valve. Turn off the supply, empty the tank, disconnect the supply line and unscrew the nut under the tank. Fit the new valve, set its height and reconnect.
Set the float so the fill stops about one inch below the top of the overflow pipe. Hard water scale clogs older valves, so this is a common repair in Thornton.
Other causes
A cracked overflow tube, a worn flush valve seat and a tank bolt leak are less common. If the toilet runs in cycles every few minutes, a leaking flapper is almost always the reason.
If you do not want to do it yourself, see toilet repair and call for help. A plumber can replace several parts in one visit.
Test and monitor
After repairs, flush and watch for a refill. Repeat the dye test an hour later. Check the water meter with everything off to confirm the leak has stopped.
If your bill was high, see leak detection for other sources.
Find the cause in two minutes
Take the tank lid off and listen. If water trickles into the tank constantly, the fill valve or the flapper is the usual suspect. Add food coloring to the tank, hold off flushing for a quarter hour, then check the bowl. Tinted water there tells you the flapper is not sealing.
If the water level reaches the top of the overflow tube and spills into it, the fill valve will not stop the flow. If the level stays below the tube and the tank refills every few minutes, the flapper is letting water slip past.
Parts that fix most cases
A new flapper is inexpensive and swaps in without tools in most tanks. Match the size, usually two or three inches, to the drain opening, and check the chain length so it has a little slack when the flapper is closed. Too tight keeps the flapper open, and too loose can tangle.
A fill valve that sticks or hisses can be replaced in about twenty minutes. Turn off the supply, flush the tank, disconnect the supply line, unscrew the old valve from the underside, install the new one and set the water level to the mark on the overflow tube. Hard water leaves scale on these parts, so they wear faster here than in a soft-water town.
When the toilet keeps running anyway
A rough or pitted flush valve seat can stop a good flapper from sealing. Light sanding sometimes helps, and in a worn tank the cleaner answer is a new flush valve or a new toilet. Cracks in the tank are another reason to replace it.
A toilet that keeps running can lose a large amount of water each day, and the cost appears on your bill. See toilet repair and installation if you would rather have the work done, and our guide on a high water bill for other causes.
Small habits that save trouble
Check the tank parts once a year when you clean the bathroom. Do not use drop-in bleach tablets, since they can harden rubber parts and shorten flapper life. Know where the shutoff valve behind the toilet is, and turn it a little now and then so it does not seize.
If you hear the toilet refill at odd hours, a phantom flush, it is the flapper. Fix it soon.
Dual flush and older tanks
Some tanks have a dual flush valve, and others use a canister-style fill valve. Take a photo of the parts and the brand name before you shop, since a mismatched part will not seal. If your toilet is more than a few decades old, parts may be hard to find, and a new toilet may be the cheaper path.
Know your shutoff before you start
Before you open the tank, close the valve behind the toilet and flush once to empty it. Keep a towel and a small bucket nearby, because the supply line holds a little water. If the valve will not close fully or drips at the stem, that valve needs replacing first, and it is a quick job for a plumber.
Quick answers
Asked about running toilet
A bad one can lose thousands of gallons in a month, so repair it soon.
Food coloring in the tank shows up in the bowl if it leaks.
Usually. Parts are inexpensive and swap quickly.
A slow flapper leak makes the fill valve cycle on and off. That is called phantom flushing.
Connected services
Leak Detection
Pinpoint where water is escaping inside walls, beneath floors or along the buried line before anything is opened up. Open page
Faucet & Sink Repair
Quiet a dripping tap, bring back full flow and swap out seized stop valves and outdoor spigots. Open page
Related reading
Toilet will not flush
A toilet that will not flush usually has a handful of causes, from a lifted chain to a blocked main line. Here is how to sort them. Open page
Why the water bill is so high
A jump in the bill usually has a short list of causes: a leak, a seasonal change, an irrigation setting or a billing mistake. Here is how to sort them. Open page
Tracking down a hidden leak
Reading the meter, dyeing the toilet tank and walking each room will turn up most leaks. Here is the order to do them in. Open page
Toilet still running?
Phone and describe the sound and how long it runs.