Yes, some do, but remember, many folks are on postage stamp-sized lots, so they may not have room for a lot of bins of water. I would like to do a real water collection system off my roof, but it would mean digging some really REALLY big holes in my yard to drop water collection tanks. I don't have anywhere to put rain barrels off of my gutter downspouts (not any barrel of any worthwhile size.) Some water authorities will provide rebates on the purchase of rain barrels (1.00 per gallon up to 400 gallons), so some folks do have some rain collection systems set up. One of our neighbors down the street just moved in, and he is a landscape developer. He both 3 huge tanks (1=3,000 to 6,000 gallon tanks), and brought in his really big backhoe. He dropped all 3 tanks in his back yard, and has his roof downspouts attached, along with an overflow spout. Nice system. I have another friend in the SD Hort Society that put in about a 12,000 gallon tank in their new property. They are both civil engineers. Their house and yard system are pretty cool, as you can imagine.