of rain puts about 600 gallons of water atop a square foot house! That's a lot of free water. These cisterns collect rainwater from a nearby roof and when the tanks are full water is dispersed through a gravity-fed drip system that irrigates crops.
This is how to make a vertical garden design for planting a tower of herbs or flowers at home. It is a great space utilization idea. The idea is pretty simple and flexible. You just stack some pots together to make a tower. You can modify the idea to fit.