At 2:40 on Friday morning, the toilet refilled by itself. Nobody had flushed it. I lay in bed upstairs listening to the tank hiss for about a minute, go quiet, then hiss again, softer, and keep on hissing until I fell back asleep around 3:30.
We have one bathroom. That means one toilet. With the wedding eight days out and my sister arriving the Thursday before, this was not going on the "figure out later" list. So much for the weekend we'd kept empty on purpose.
How much a running toilet wastes
Since July I've been in the habit of reading our water meter, so Friday night I read it at 11 p.m. and again at 6 a.m., with nobody using any water in between. It moved 31 cubic feet, about 230 gallons, overnight. That's more than two days of normal use for the two of us, poured down the overflow while we slept. At what we pay per unit for water and sewer, a month of that would have been real money.
Tries one and two: flappers
Every video I watched said a toilet that refills on its own has a leaky flapper, the rubber seal at the bottom of the tank. Ours looked old and a little warped, so on Saturday morning I bought one for $7.
It was the wrong size. Flush valve openings mostly come in 2-inch and 3-inch, and I'd guessed instead of measuring. Back to the store, this time with the old flapper in a sandwich bag, to return the $7 one and buy the right size for $9. I paid for that one with a Menards rebate check from the kitchen junk drawer, so technically it was free, or at least prepaid.
New flapper in, chain adjusted with a little slack, and the phantom refills stopped. The hiss did not. Saturday night it was still running, a quiet trickle you could only hear with the bathroom door shut.
Sunday I fiddled with the chain again, then the float on the old fill valve, then the chain again. Tessa walked past the bathroom with a garment bag over her shoulder and said, "Erin gets here Thursday, and that wall is thin."
What I should have done first
Sunday evening, I finally did the dye test. You put a few drops of food coloring in the tank, don't flush, and wait twenty minutes. If color shows up in the bowl, water is getting past the flapper. Our bowl stayed clear. The new flapper was sealing fine.
Then I did the thing I should have done on Friday: took the lid off the tank, sat on the edge of the tub and just watched. The water level was creeping up past the top of the overflow tube and trickling down into it. The fill valve wasn't shutting off all the way, no matter where I set the float. The old flapper had probably been leaking a little too, which explains the refills, but the hiss all night long was the fill valve.
Monday after work I bought a Fluidmaster fill valve for $19. I shut off the water at the stop behind the toilet, an old multi-turn valve that I turned very gently, expecting it to start leaking. It only wept a little at the packing nut until I snugged it a quarter turn. Then I flushed, sponged out the tank, unscrewed the old valve from underneath and set the new one in. The old valve had a crust of mineral scale around its seal, and the rubber washer inside was flattened hard as a coin, so no amount of float adjusting was ever going to fix it. The new one adjusts for height, so setting it took about two minutes. I set the water line an inch below the top of the overflow tube, turned the water back on and listened.
Nothing. It's been quiet for a full night, and the meter barely moved.
So: two flappers and a fill valve over four days, when looking inside the tank first would have pointed me to the $19 part on Friday. The house sheet line for this job says $19, since the $7 flapper went back and the $9 one was paid for with rebate money.
Trip count: 3.
