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Plastic piping (if equipped) functions as a water hammer arrestor. An expansion tank will as well, though a picky inspector may insist that the automatic valve location must have a water hammer arrestor if you are piped with metal supplies.

I know expansion tanks are required by IRC these days and those can help with hammer a bit too, as they're doing a similar function.

It happened to me once, now I turn off the water when I go on vacation.