Brad Lancaster has a series of books: Harvesting Rainwater for Drylands & Beyond Vol. 1 & 2.
 
 Vol. 1 is heavy into the principals - well worth a read (in your public library?)
 Vol. 2 is the nuts-and-bolts of making it work - this one should be in your home.
 
 He is a native of Tuscon, AZ, so he understands the importance of utilizing every available drop.
 
 Both are available from Amazon, other book sellers, AND 
Rainwater Harvesting   , his site.
 He also has a few YouTube videos available.