This is a short post, but useful. We had a moaning toilet. This was “our two-mode commode” described previously, but the same thing happens with one-mode commodes too. I cured it. At issue, the toilet moaned or wailed after it was flushed. Either the toilet was possessed by a tormented soul, as sometimes happens, or the moan was caused by a vibration in the fill diaphragm. That was the case here.

It’s usually toilets in social science university buildings that get inhabited by tormented souls, as these are typically social scientists who are forced to come back this way as punishment for passing themselves off as real scientists. Sometimes they show up making the heating pipes rattle and clang. You can cure this by bringing in a plumber or heating professional to encourage the soul to repent. The heating professional then adjusts some things and the soul moves on. In our case, a toilet in a private home, it required no exorcism, just an adjustment of the flow.

In our case, it became clear that the fill valve had become partially blocked resulting in a high flow against the diaphragm. This diaphragm, shown below, is in the valve that gets closed when the float in the toilet tank rises. At high flows the diaphragm begins to vibrate and moan, sounding just like a possessed toilet.

For most toilets, replacing this diaphragm is an easy repair: buy a new diaphragm for about $4, (and typically, also a new flapper — it’s a good idea to change the flapper every 4-6 years), remove the old diaphragm. It’s behind a thumb-nut, typically, and do the necessary exchange. Remember, thumbnuts are better than others. Sorry to say, our toilet has a new-fangled float mechanism where the diaphragm is hidden inside, not easily replaced. A normal thing to do is to replace the float mechanism, but those cost $30 or more, and take a fair amount of work. Instead, I choose to reduce the flow speed of the water by partially closing the inlet valve sending fill water to the commode. It now fills slightly slower than before, but since there is less flow, there is no longer any audible vibration. A quick fix at zero cost.

If that hadn’t worked, I’d have called in the exorcist, an expensive proposition. You have to pay your the exorcist. If you don’t, you get repossessed.

Robert Buxbaum, March 25, 2026. I’d run for water commissioner, sewer commissioner. Here are some sewer jokes and a song from my campaign. There are also some links to serious matters of sewage treatment, water purity, and the problems of combined sewers.