An industrious friend of mine is planning life off of the grid. She will grow her own food, utilize alternative forms of energy, and supply her own water (without having to dig a well). Recently she questioned, is it possible to provide water for a home using only rainwater? In my neighborhood in Washington, many people use barrels under gutters to collect rain for simple gardening needs, but homes in this area that harvest rainwater for all household needs are few and far between.
Above Photo: World Hunger Year
The average American uses 80 to 100 gallons of water per day for cooking, washing, bathing, and cleaning. Still, it is possible to build a home in the United States that uses only rainwater (with a few water conservation measure implemented) for all daily needs. The amount of water supplied through rainfall events depends largely on location. Even areas with little precipitation are able to capture sufficient amounts of rainwater during seasonal occurrences as evidenced in India. If you know average precipitation , it is possible to calculate the amount of rainfall available for capture using simple math as shown in this post on Rain Barrel.net. After determining the amount of rainfall possible for capture, system design should evaluate the following parameters:
1. Collection Methods
2. Storage Methods
3. Water Conveyance
4. Treatment Process
This guide published by the Texas Commission on Environmental Quality provides a wonderful overview of “Harvesting, Storing, and Treating Rainwater for Indoor Domestic Use”. While homes in the US relying on rainwater for all needs are not very common, there are people using such systems with great success. Understanding and installing rainwater catchment systems now could greatly reduce risks associated with decreased water availability in the future.