Your Lone Star State Rainwater Harvesting Resource

http://www.arcsa.org American Rainwater Catchment Systems Association.
http://rainwaterharvesting.tamu.edu Rainwater Harvesting, Texas A&M University.
http://www.twdb.state.tx.us Texas Water Development Board
http://www.waterwisetexas.org Water Wise Council of Texas
http://wateriq.org Water IQ
http://www.texaswaterinfo.org Texas Water Information
http://www.texaswatermatters.org Texas Water Matters
http://texaswater.tamu.edu Texas Water Resources
http://www.tceq.org Texas Commission on Environmental Quality

The Texas Water Development Board has published guidelines for Rainwater Harvesting. Click the link below to download a .pdf file of those guidelines.
http://www.twdb.state.tx.us/publications/reports/RainwaterHarvestingManual_3rdedition.pdf