Banging Pipes : A non-obvious source of banging in my pipes.

(Boy, that sounds sexual, doesn't it? It isn't.)

For nearly a week last summer (maybe 5 days) I noticed a loud repetitive banging coming from the pipes in my house. I'd hear it in the basement, a single "bam!" every 5-10 minutes. I hadn't heard it before, and I was wondering what it was.

I was ready to dismiss it (although it's a little annoying if you're trying to read sitting in the living room, and your silence is periodically interrupted) as a common household noise, and assume it would go away.

But then I decided to search on the 'net, and the only references I could find to banging pipes was with steam-fed radiators [which, BTW, should not make that noise: word on the street is that it's indicative of a problem which needs to be fixed. I guess all that banging I used to hear on winter mornings in high-school could have been avoided.] and that banging in the pipes can be a rather damaging thing.

"Well, crap," said I. "What'll I do?"

For a couple of days I sat and worried about it, thinking of mailing everyone I knew who owned a house to see if they knew what it could be. I noticed that it was a little more frequent in the day than at night.

Magically, I suddenly realized what was causing it, fixed it, and it's all better!
Can you guess what the problem was?

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I bought a bunch of fantastic little doo-dads which go on the ends of your hoses and watering paraphanelia, which not only make it easy to attach/unattach items (just push-them-together) but they also have valves in them to prevent the water from flowing unless it's hooked together. (This is FABULOUS! When you're done using the sprinkler, just unplug it from the hose, and the water stops flowing!) This leads to us sometimes forgetting to turn off the spigot. (When all is well, there are no leaks, so I figured this was no problem.)

However, the hose was lying there, in the sun, heating up, attached and open to the house water supply, and I guess the valves were occasionally releasing a bit of pressure and WHAM water would go into/out of the house.

I wanted to let you all put this piece of knowledge in your brains in case something similar occurs to you.