An inch of rainfall doesn't sound like much. But when it falls on an average-size roof, it adds up to a 1,900-gallon torrent sluicing off the eaves. That's an awful lot of water that can cause an awful lot of damage if your gutters aren't up to the task of controlling it. Yet we barely give gutters a second thought until they're clogged and overflowing, or ripped from their moorings by ice and snow.