The time is coming in southeast Texas that the need for and the use of rainwater harvesting is going to be huge. The Texas Agrilife Extension Service, http://agrilifeextension.tamu.edu/, a division of the Texas A&M system, has really endorsed this as a well needed fixture in the life of Texans. The system that is installed does not have to be expensive or fancy, a simple rain barrel is a great beginning. You will find that your plants love the water and its quality far more than “city water”. Most of the water that comes from a tap has been purified to the point for human consumption that there is very little nutritional value for plants. For a more extensive system, my recommendation is to hire a qualified professional to design and install it for you. ARCSA, the American Rainwater Catchment System Association, http://www.arcsa.org/, certifies professionals to do the bigger and more expensive systems. You can go onto their website to find a certified professional in your area.