Heard a sales pitch by Bushman rainwater harvesting systems. www.bushmanusa.com Interesting topic unfortunately it poured all day yesterday and we couldn't go outside to look at the two setups he had on a trailer in the parking lot. I support the effort but I just don't see how you could get enough at a typical home set up to really make much of a dent in supplying it to the irrigation beyond hand watering pots beds etc. Now if you could bury some monster size tanks that would be a different matter. If it was me I'd have the rain water used in the house for showers, clothes washing, etc and get bottled water for consumption use. The tanks need to have an alternate source to avoid running dry which uses an air gap back flow protection. Didn't hear the whole conversation but some cities will not allow that type of set up. The gutter set up is intersting because the first initial flush of water gets siphoned off to avoid the dirt and leaves then a ball rises up diverting the water into the tank.