Why Is My Toilet Running?
In Phoenix, three things cause almost every running toilet: a flapper that no longer seals, a float set too high, or a worn fill valve. Phoenix-area water runs 12 to 20 grains per gallon depending on the utility, and the calcium shortens flapper life by depositing on the seal. A toilet that runs continuously can waste up to 200 gallons a day, which adds up fast on a Phoenix water bill.
Most fixes are DIY in under an hour with parts from any hardware store. A new flapper or fill valve solves the common failures. If you have replaced the flapper once and the toilet still runs, the next flapper will not fix it. The flush-valve seat is pitted, and you are treating a symptom.
If you have already tried the basics and the toilet still runs, call 602-560-8989. We will tell you on the phone whether it is worth a service call or a fix you can finish tonight.
Common Causes
Faulty Flapper (Hard-Water Failure)
Phoenix-area tap water (12 to 20 GPG depending on the utility) deposits calcium on the rubber seal in the tank. The flapper warps, hardens, and stops sitting flat, so water trickles into the bowl until the fill valve cycles back on. A Korky 2014 or Fluidmaster 502 swap is the easiest fix, usually finished in 15 minutes.
Float Set Too High
Water rises past the fill line, spills into the overflow tube, and the fill valve never shuts off. Look for the 'WL' stamp on the inside tank wall and adjust so water sits about an inch below the top of the overflow tube. On modern cup-float valves, pinch the clip and slide the cup down.
Worn Fill Valve
The fill valve refills the tank after each flush. After five to ten years in Phoenix hard water, the seal hardens and the valve either won't shut off or cycles on every few minutes. A Fluidmaster 400A or Korky QuietFill swap takes about 20 minutes with the angle stop closed.
Cracked or Misrouted Overflow Tube
If the overflow tube is cracked or sitting too low, water drains continuously and the fill valve never gets to rest. The thin black refill tube clipped to the top should sit above the water line, not pushed down inside the overflow. A submerged refill tube siphons the tank between flushes and is a hidden cause of phantom flushing.
Why Another Flapper Won't Fix It
After several years, the flush-valve seat builds a rough calcium ring that no new flapper can seal against. This is why replacing the same flapper twice in a year never holds; the failure has moved from the rubber to the seat itself. Scrub the seat with a vinegar rag, or replace the flush valve if it is pitted underneath.
Chain Length Wrong
A chain that is too short holds the flapper open after every flush; too long, and it slips under the flapper and breaks the seal. Aim for about a half inch of slack with the flapper closed. Brass chains that have turned green are corroded and should be replaced before they snap mid-flush.
What Should You Do?
Try This First
- Lift the tank lid and watch one full flush cycle. If water keeps spilling into the overflow tube after the tank refills, the float is set too high.
- Add five drops of food coloring to the tank, wait ten minutes without flushing, and check the bowl. Color in the bowl confirms a leaking flapper.
- Shut off the angle stop under the toilet. Flush once to drain the tank, sponge out the last cup of water, and drop in a new flapper. Hook the new chain with about a half inch of slack.
- Adjust the float so water sits about an inch below the top of the overflow tube. On modern cup-float valves, pinch the clip and slide the cup down. On older ball-float valves, turn the adjustment screw clockwise a quarter turn at a time.
- If the fill valve hisses or cycles back on after the tank fills, swap it for a new fill valve. Shut off the angle stop and unscrew the locknut under the tank. Drop the old valve out and seat the new one with the gasket facing up.
- Clean the flush-valve seat with a vinegar-soaked rag for 30 minutes. Then scrub with a plastic pad to remove the calcium ring Phoenix hard water leaves behind.
- Test with three flushes in a row. The fill should shut off cleanly and the tank should stay quiet for five minutes. Any hissing or trickling means the flapper still isn't sealing or the fill-valve seat is pitted.
Call a Pro If...
- You have already replaced the flapper and the toilet still runs (the flush-valve seat is pitted and needs full valve replacement)
- The fill valve won't shut off after replacement, or hammers loudly when it closes (incoming pressure is likely over 80 PSI)
- Water is pooling at the base of the toilet (failed wax ring or cracked porcelain, separate from the running issue)
- The toilet is over 25 years old and on its third repair this year (a 1.28 GPF replacement is usually the better call)
- The tank or bowl has a hairline crack (no repair makes that safe, the toilet has to come out)
- You hear water running between flushes but food coloring does not show in the bowl (the leak is below the tank, not in it)
- Phantom flushes continue after a new flapper and a new fill valve (the refill tube is misrouted or the flush-valve gasket is leaking)