Talk about rain! We average a little over 30 inches of rain annually, according to the weather bureau's long-term statistics (our local Chamber of Commerce quotes 32 inches, but they have a vested interest, so...). However, by 4:00 p.m. yesterday we had over 4 inches in a 24 hour period. In south Austin, which is about 70 miles east of us, they had over 13 inches of rain in that same period and of course horrendous flooding, 1 or 2 deaths, etc. I wouldn't suggest buying a used car from a private party in Austin in the immediate future unless you know the person really well. Those minnows in the dashboard have a tendency to short out things after awhile.
Our four tanks filled overnight after 1 inch of rain, but that's not surprising considering that we are collecting from 4,799 square feet of roof surface. Even if you figure 70% to 80% efficiency, that still counts up rapidly. We really need to start thinking about one or more large tanks, as it bothers us to see the excess water pouring out of the overflow drains. Next summer during our annual drought and our 100+ degree heat, we'll wish we had that water.