A leaking toilet is usually a worn flapper or a bad fill valve, and it can waste more water than any other fixture in the house. Put a few drops of food coloring in the tank; if color shows in the bowl without flushing, the flapper is leaking. Most fixes are a same-day flapper or valve replacement.
The flapper: the biggest hidden water waster
Ask any working plumber what wastes the most water in a house and you get the same answer: the toilet flapper. It's a five-dollar rubber seal at the bottom of the tank, and when it warps or gets coated with mineral scale. Common with hard water at about 11 grains per gallon. It stops sealing. Then tank water seeps into the bowl around the clock, silently, 24 hours a day. The toilet may never make a sound. The water bill tells the story instead: with Citrus Heights Water District charging about $1.35 per unit of 748 gallons, a running toilet can add unit after unit to every bill until it's fixed.
The dye-tablet test (60 seconds)
You don't need us for this one. Run it right now:
- Lift the tank lid and put a few drops of food coloring (or a dye tablet) into the tank water. Don't flush.
- Wait 15 to 20 minutes.
- Look in the bowl. Any color in the bowl means the flapper is leaking tank water straight through.
- No color? Your flapper is sealing. If the toilet still runs, the fill valve is the suspect. See below.
Flapper vs fill valve: which one is bad
Two parts cause nearly every toilet leak. Here's how to tell them apart:
- Flapper (tank-to-bowl seal). Fails the dye test above. Also listen: a toilet that briefly refills on its own every so often (“phantom flushing”) has a flapper seeping just enough to drop the tank level.
- Fill valve. Look inside the tank: if water is constantly running into the overflow tube, or the water level sits above the overflow line, the fill valve isn't shutting off. Jiggle the float. If the running stops, the valve or float needs adjusting or replacing.
- Wax ring / base. Water on the floor around the base after flushing points to the seal between the toilet and the floor, not the tank parts. That's a pull-and-reseat job.
When we get the call
Most toilet leaks end with a same-day flapper or fill valve replacement. Quick, inexpensive, done. Call us when new parts don't stop the running, when water appears at the base (wax ring or a cracked bowl), when the shutoff valve behind the toilet is frozen or leaking, or when the bill stays high after the toilet checks out. That means the leak is somewhere else, and we'll run the full hidden leak workup. (123) 456-7890.
Frequently asked questions
How much water does a leaking toilet waste?
A lot more than it looks. A flapper that seeps silently can waste hundreds of gallons a day, and a toilet that runs audibly wastes far more. Often enough to double a water bill. Because it's silent, most people find out from the bill, not the bathroom.
Why does my toilet run every few minutes on its own?
That's called phantom flushing. The flapper is seeping tank water into the bowl, the tank level drops, and the fill valve kicks on to top it up. Replace the flapper and it stops.
I did the dye test and the bowl turned color. What now?
The flapper isn't sealing. Turn off the toilet's supply valve, flush to empty the tank, and replace the flapper. It clips on in minutes and costs a few dollars. If a new flapper still leaks, the flush valve seat underneath may be rough or cracked, and that's a call to us.
Water is on the floor around the toilet base. Is that the flapper?
No. That's the wax ring seal between the toilet and the floor, or possibly a cracked bowl. It needs the toilet pulled and reseated with a new ring. Don't caulk around the base to hide it; trapped water rots the subfloor.
Can a toilet leak cause a high water bill even if I never hear it run?
Yes, and that's the most common case. A slow flapper seep makes no sound at all. If your bill jumped and the meter test shows water moving with everything off, check every toilet with the dye test before assuming a bigger problem.
Why is my toilet rocking or leaking at the base?
A rocking toilet usually means the base seal has failed or the floor under it is damaged, and water can leak at the base with each flush. Do not keep using it and do not just tighten the bolts, as that can crack the base. The seal and floor need to be checked.
Related
- Hidden water leak detection
- High water bill investigation
- Water heater leaking
- Frequently asked questions
Think you have a leak?
Call AquaTrace Leak Detection to describe what you are seeing in Citrus Heights and get a plan to find it.
Call (123) 456-7890Last updated: October 25, 2026.