Toilet running constantly or randomly
A toilet that runs is refilling a tank that is losing water, or overfilling one that isn't. Lift the tank lid and watch.
- Water trickling into the overflow tube: the fill valve shuts off too late. Lower the float, or replace the fill valve if adjusting doesn't hold.
- Refilling every few minutes with no one using it: water leaks past the flapper into the bowl. EPA's test is a few drops of food coloring in the tank; color in the bowl without a flush confirms it.
- A chain that snags under the flapper: the flapper can't close. Shorten the chain so it has a little slack.
Fixr puts a flapper replacement at $60 to $120 and a fill valve at $60 to $150, and a running toilet fix in general at $50 to $400, depending on how many parts are worn.
Toilet leaking at the base
Water around the base after a flush usually means the wax ring no longer seals the bowl to the closet flange in the floor. A toilet that rocks breaks that seal, and loose or corroded closet bolts let it rock. The repair is to lift the toilet, scrape off the old wax, check the flange, set a new ring and reset the toilet on new bolts. Fixr lists a wax ring or seal repair at $60 to $150 and a flange repair at $60 to $200. Water at the base that appears without flushing is something else: condensation on the tank in humid weather, a leaking supply connection, or a crack in the porcelain.
Weak or incomplete flush
A weak flush has causes in the tank and in the bowl. In the tank, the water level may be set too low, or the flapper may close before the tank empties. In the bowl, mineral scale can block the small rim holes and the siphon jet, which starves the flush. A partial clog in the trapway, often from a small object, causes the same symptom and needs a closet auger, not a plunger. If several fixtures drain slowly too, the problem is further down, and the clogged drain page is the better guide.
Toilet won't stop rocking
A toilet that rocks on a level floor usually has loose closet bolts or a flange that sits above or below the finished floor. Tightening the bolts too hard cracks porcelain, so shims come first. If the flange is broken or the floor around it is soft, the repair extends to the flange and possibly the subfloor, which is when the price climbs past the typical range.
Repair or replace the toilet
Toilets are among the largest users of water in a home: EPA counts them as nearly 30 percent of an average home's indoor use, and older models can use as much as 6 gallons per flush. The federal standard is 1.6 gallons per flush, and WaterSense-labeled toilets use 20 percent less than that. When a toilet from before the federal limit needs more than a flapper, replacing it often pays for itself in water. A cracked tank or bowl can't be repaired at all.
| Repair | National range |
|---|---|
| Flapper replacement | $60–$120 |
| Fill valve replacement | $60–$150 |
| Wax ring or seal | $60–$150 |
| Flange repair | $60–$200 |
| Running toilet, all causes | $50–$400 |
| After-hours surcharge | +$100–$300 |
Source: Fixr national toilet guide, updated January 31, 2025. Typical repair about $125.
Permits and toilet work
The International Plumbing Code (§106.2) lists the removal and reinstallation of water closets among work exempt from permits, as long as no valves, pipes or fixtures are replaced or rearranged. Resetting a toilet on a new wax ring therefore usually needs no permit. Moving a toilet or changing the drain under it is not. Other fixtures are covered on our plumbing fixture repair page.
Toilet problems, answered
Why does my toilet run on and off by itself?
Water is slowly leaking from the tank into the bowl, usually past a worn flapper, until the fill valve kicks on to refill it. A food coloring test confirms it, and a new flapper is the usual fix.
Is a toilet leaking at the base dangerous?
It isn’t an emergency, but it shouldn’t wait. Water under the toilet is often sewage-tainted, soaks the subfloor, and a broken seal lets sewer gas into the room. Stop using that toilet until it is reset.
Can I replace the wax ring myself?
It is a common DIY job if you can lift the toilet safely and the flange is intact. If the flange is cracked or the floor under it is soft, the job becomes a repair to the flange and possibly the subfloor.
When is a new toilet the better repair?
When the porcelain is cracked, when the toilet predates the 1.6-gallon federal limit, or when you have replaced several parts in a year. EPA notes older toilets can use as much as 6 gallons per flush.
Sources
- Toilet Repair Cost, Fixr, updated January 31, 2025.
- WaterSense: Residential Toilets, U.S. Environmental Protection Agency, updated May 29, 2026.
- Fix a Leak Week, U.S. Environmental Protection Agency, updated March 13, 2026.
- International Plumbing Code 2021, Chapter 1: Scope and Administration (§106.2, work exempt from permit), International Code Council.
Reviewed September 27, 2026. Found an error? Write to admin@plumbingrepairquotes.com.