General
Texas Manual on Rainwater Harvesting
http://www.twdb.state.tx.us/publications/brochures/conservation/doc/RainwaterHarvestingManual_3rdedition.pdf
Gutter Design
Architectural Design Handbook: Gutters and Downspouts
http://copper.org/applications/architecture/arch_dhb/gutters_downspouts/downspouts.html
Gutter Design - Hunter Plastics
http://www.hunterplastics.co.uk/rainwater/gutterdesign/default.html
Roof, Eaves, Gutter and Downspout Calculator
http://www.roof-gutter-design.com.au/Downp/applet.php
Tanks
Rainwater Tanks: Their Selection, Use and Maintenance
http://www.ircsa.org/factsheets/AustraliaRainwater.pdf
Water Quality
Guidelines for Drinking Water Quality
http://www.who.int/water_sanitation_health/dwq/GDWQ2004web.pdf