· And with 10 rain barrels full of water here s the next problem A gallon of water weighs 8 34 lbs A filled 50 gallon rain barrel weighs 400 lbs making 10 rain barrels weigh 2 tons That means with 10 rain barrels you would have extremely heavy concentrated weight pushing down on your home s Zone of Failure 24 hours a day 7 days a week }