[Vision2020] And Now For Something Completely Different!

[joeh]

> I have about 1,500 square feet of roof surface which using your figure of 20
> inches of rain a year works out to around 2,500 cubic feet of water.  A
> cubic foot of water at sea level and 20 degrees C is slightly less than a
> gallon so in rough numbers we are looking at 2,200 gallons of water.  Now a
> large part of it falls when I don't need it, but capturing a third of it
> would be more than enough for my gardening needs.

Your calculations for the cubic feet of water is correct with the given data.  But there are 231 cubic inches in a gallon.  That means there are 7.48 gallons in one cubic foot (1728 cubic inches in a cubic foot), not "slightly less than a gallon".  Therefore you are looking at about 18,700 gallons of water per year.  One third of that is about 6000 gallons.


Joe Huffman
Senior Research Scientist
Pacific Northwest National Laboratory
Richland, WA

509-375-2201