Toilet runs every few minutes at night? It's the flapper (2 a.m. edition)

The toilet in the hall bathroom started running again around 2 a.m., because that is the only hour toilets do anything. Deb heard it first. She has a way of not saying a word that says the whole word.

I have a history with this exact toilet. In 1998, three weeks into owning this house, this same toilet ran and I took the tank apart and made it worse and paid a man $140 to fix in eleven minutes what I had turned into a two-hour problem. That toilet is why the spreadsheet exists. So there is something satisfying about the fact that 28 years later I fixed it myself, in the dark, for the price of lunch.

What's actually happening

Lift the tank lid. That rubber piece at the bottom that lifts when you flush is the flapper. It is supposed to drop back down and seal like a drain plug. Rubber gets old, stiff, and warped, and it stops sealing. Water sneaks past it into the bowl. The tank level drops, the fill valve wakes up and tops it off, and you get that little run every few minutes all night. Some people call it a phantom flush. It is not a phantom. It is a six dollar part failing quietly.

Want to be sure before you buy anything? Put a few drops of food coloring in the tank, do not flush, and wait fifteen minutes. If the color shows up in the bowl, it is the flapper. That is the whole diagnosis.

One thing to check before you go to the store, and this trips people up. Look at the drain opening at the bottom of the tank. If it is about the size of a baseball, you have a 2 inch flush valve and you want a 2 inch flapper, which is what most older toilets take. If it is closer to a softball, you have a 3 inch valve, common on newer toilets, and a 2 inch flapper will never seal on it no matter how you fight it. Buy the size that matches the hole.

The fix

1. Shut the water off at the valve behind the toilet, then flush to empty the tank.
2. Unhook the old flapper from the two pegs on the overflow tube and unclip the chain from the flush lever.
3. Take the old flapper WITH YOU to the store, or better, read the model number stamped inside the tank first. This is the whole ballgame and I will come back to it.
4. Hook the new flapper onto the pegs, clip the chain to the lever with about a half inch of slack, turn the water back on, and test a few flushes.

What went wrong

I did not read the model number. I grabbed the flapper off the peg that looked right, drove home, and it was a hair too small, which on a flapper means it does not seal, which means I drove back. Two trips for a twenty minute job. They sell about fourteen flappers that all look like the same rubber donut and they are not the same rubber donut. Check the number inside your tank before you leave the house. Learn from me. The quarter in the jar is for what I said in the aisle on trip two.

If a new flapper does not fix it

Then the water is leaving some other way. If the tank never stops filling and you hear a steady hiss, that is the fill valve, not the flapper, and that is a different twenty minute job I will write up another time. If water is running over the top of the overflow tube, your fill valve is set too high and needs turned down. But nine times out of ten at 2 a.m., it is the flapper, and you do not need a plumber. You need a six dollar part and the humility to check the model number, which I did not have, in 1998 or last week.

Deb's verdict. "Twenty-eight years. I would say you are getting faster but you made two trips."