You hear it at night: a short hiss, then the tank refills even though nobody flushed. Or the water never quite stops trickling into the bowl. A running toilet is easy to ignore, but it can waste a surprising amount of water and quietly push up the bill.

In a hard-water area like Fullerton, mineral scale also builds on the moving parts inside the tank, so flappers stiffen and fill valves stick sooner than they otherwise might.

The parts inside the tank

Flapper
The rubber seal at the bottom of the tank that lifts when you flush and drops to hold water in.
Fill valve
The tall assembly on one side that refills the tank and shuts off when the float rises.
Float
A cup or ball that rises with the water level and tells the fill valve when to stop.
Overflow tube
The open pipe in the middle that sends excess water to the bowl if the level rises too high.
Stop valve
The small valve on the wall behind the toilet that shuts off its water supply.

What the symptom points to

  • IfThe tank refills every so often without a flushThenWater is leaking past the flapper. It may be worn, warped or blocked by a misaligned chain.
  • IfWater keeps running into the overflow tubeThenThe water level is set too high or the fill valve is not shutting off.
  • IfThe handle has to be jiggled to stop itThenThe chain is too long or snagging, or the handle mechanism is sticking.
  • IfWater appears on the floor around the baseThenThis is a different problem, possibly the wax seal or a cracked bowl. Stop using it and call a plumber.

Simple checks you can make

  1. Do the dye test.Put a few drops of food coloring in the tank, wait without flushing, and look for color in the bowl.
  2. Check the chain.Lift the lid and make sure the chain has a little slack but is not long enough to catch under the flapper.
  3. Look at the water level.It should sit below the top of the overflow tube, usually near a marked line.
  4. Close the stop valve if needed.If it will not stop running, turn the valve behind the toilet clockwise until the tank stays quiet.

Repair the parts or replace the toilet?

Replace tank parts

  • Fits most running-toilet problems.
  • Usually a quick repair with standard parts.
  • Keeps an otherwise sound toilet in service.

Replace the toilet

  • Worth discussing if the tank or bowl is cracked.
  • Sometimes considered for very old, high-volume models.
  • Involves a new wax seal and setting the toilet on the flange.

Common questions

Is a running toilet an emergency?

Usually not, but it should not wait long. Close its stop valve if it runs constantly, and schedule the repair.

What affects the cost of the repair?

Mostly which parts need replacing, the condition of the stop valve and supply line, and whether the toilet has an unusual or older design.

Can scale cause the toilet to run?

Yes. Hard water can stiffen the flapper and gum up the fill valve so neither seals or shuts off properly.

General information for Sunny Hills, not a quote or professional advice. In an emergency, call 911.