Did you know...? (stuff about water)

I've been looking into rain harvesting--collecting the rain off my roof into containers to use for watering my garden and flower beds. My roof has both hip and gabled ends and I have a total of five downspouts. I was thinking of 55 gallon drums with added spigots for attaching hoses for each downspout.
The way the roof lines run, one downspout would actually catch much more water than the others, but surely the five 55 gallon drums would be enough, right?

It turns out -- probably not.
For every 1000 square feet of roof surface and 1" of rainfall you can harvest 623 gallons of water! 
No wonder rain harvesting is illegal in many areas that are susceptible to drought. That's a lot of water!

I was having a hard time wrapping my pea brained head around the 623 gallons thing so I thought I'd break it down to something more relatable--one cubic foot. How many gallons in just one cubic foot of water?
The answer is just as mind blowing--almost 7.5 gallons!
Wait! A cubic foot is one and a half times a standard 5 gallon bucket?
Yep. I measured a bucket and the base is about 12" in diameter.

For me, harvesting water isn't that big of a deal since I don't pay for water anyway. We are on a well and the only thing I have to pay for is the electricity to pump the water. Also, we are in an area that gets plenty of rain and the surface area of my roof is but a tiny fraction of the 5 acres we own. Collecting rain water for gardening doesn't really make me more or less self-sufficient than pumping it out of the well. It feels like it should, but it doesn't. 
Once we get our solar panels and battery up (a future project) we'll be much more self-sufficient, but that's still down the road a bit. We have a liquid propane (LP) tank to fuel our furnace, gas range, and fireplace, so unless we make some other conversions, we will still be reliant on the fossil fuel industry. Converting to electric heat would be simple enough, but I really do prefer to cook with gas and the gas fireplace is nice, too. 

Just stuff I learned yesterday.

John