Toilet keeps running? Fix it in 15 minutes for under $20

A running toilet is the most expensive "minor" problem in the house — a bad flapper alone can add $50–$100 a month to a water bill. It's also the easiest plumbing repair there is. No tools required for two of the three fixes.

Lift the lid and watch

Flush it and look. One of these three things is happening:

1. Water is trickling into the overflow tube (the open vertical pipe in the middle). The fill level is too high or the fill valve won't shut off.
2. Water level is fine, but you hear a periodic refill ("ghost flushing") every few minutes. The flapper is leaking.
3. The flapper stays open after a flush or the handle has to be jiggled. Chain is too long/short or the flapper is misaligned.

Fix 1: Water level too high

There's a float — either a ball on an arm or a cup that slides on the fill valve shaft. Adjust it so the water sits about 1 inch below the top of the overflow tube.

• Ball float: bend the arm gently downward.
• Cup float: pinch the clip and slide the cup down, or turn the adjustment screw on top.

If the valve still won't shut off at any float setting, the fill valve is worn. A universal replacement is $12 and a 15-minute swap (shut off the supply, flush to empty, unscrew the nut under the tank, drop in the new one).

Fix 2: Flapper leaking (the usual culprit)

Drop a few drops of food coloring in the tank. Don't flush. If color shows up in the bowl within 15 minutes, the flapper isn't sealing.

Flappers warp and harden with age (and with in-tank cleaner tablets, which destroy rubber — stop using those). Replacement is $5–$10:

1. Shut off the supply valve behind the toilet. Flush to drain the tank.
2. Unhook the chain from the handle arm. Pop the flapper off the two pegs on the overflow tube.
3. Take the old one to the store — size and style vary. Or buy a universal adjustable one.
4. Hook the new flapper on, reattach the chain with about 1/2 inch of slack, turn the water back on.

Fix 3: Chain or alignment

Too much slack and the flapper doesn't lift fully. Too little and it can't seat. You want the chain just slightly loose when the flapper is closed. Also check that the flapper is centered on the drain seat — it's easy to hook it on crooked.

The one case to call a plumber

If the toilet runs and there's water on the floor around the base, or the bowl level drops on its own without the tank refilling, you may have a cracked bowl or a failed wax ring. That's a toilet pull, which is still DIY-able but a different afternoon. If you'd rather not, a plumber charges $150–$300 for it.

While you're in there

Replace the fill valve and flapper together if the toilet is over 10 years old. A complete repair kit is about $20 and gets you another decade of silence.