Harvesting rainwater involves diverting the rainwater runoff, usually off of a roof, into an on-site storage container or a cistern to be used at a later time. The collected water is used for various outdoor and indoor non-potable (or non-edible) purposes.
Beginning with the Basics
Year after year, much of the United States faces drought conditions – or “periods of dry weather” as defined by Webster’s Dictionary. Since water is essential to all living creatures, it is important to learn how to conserve our drinking water.
All you need for a basic setup is a rain barrel and a gutter with a downspout to direct the water to the barrel. Although, more elaborate systems consist of large cisterns that can be installed above ground or below ground to supply your non-potable needs. Recommended non-potable uses of harvested rainwater include –
- Hand watering lawns and gardens
- Connecting a cistern to a lawn and garden irrigation/sprinkler system
- Washing vehicles
- Bathing pets
- Using to fill fountains or fish ponds
- Flushing toilets
- Washing laundry
- Cleaning buildings exteriors
With the advancement of technology and the realization of the need to conserve water, companies have made drastic changes in energy and water efficiency for appliances. For example, in the 1960s, it took six (6) gallons of water to flush the toilet one (1) time. Now every toilet that has been manufactured since 1994 uses 1.28 gallons max per flush.
The lowly washing machine is another example of an advancement inefficiency. Older washers used 29 to 45 gallons of water per load, however, the newer high-efficiency can wash the same load of clothes only using 15 to 30 gallons.
Just by using harvested rainwater to flush toilets and wash laundry, an average family will save hundreds of gallons of water per week even if higher-efficiency appliances are used.
How to calculate the amount of rainfall
While there are online calculators to help figure out the amount that can be collected, here is a simple formula that is easy to remember. 1 inch of rain x 1 square foot = 0.623 gallons, in other words – 1” of rain over 1000 square foot area will yield 623 gallons of rainwater.
Things to know
Before beginning your harvesting rainwater excursion, you will need to check all local and state municipalities because while most states encourage the practice, even offering incentives, other states have laws and codes in place.
Also, another source of information is the Environmental Protection Agency (EPA). They offer a Municipal Handbook – Managing Wet Weather with Green Infrastructure that discusses policies and aspects of harvesting rainwater.
Not only does a rainwater harvesting system reduces dependence on public water supply and simultaneously reduce the monthly water bill, but it also offers environmental benefits by efficiently using the earth’s natural resources.
To find the best options for your property and be assured that you meet any state and local codes and requirements, contact a professional plumbing engineer.
Michael Tobias is the founder and principal of Chicago Engineers. He is a graduate of Georgia Tech class of 2004, with a Bachelor of Mechanical Engineering with honors. His innovative approach to MEP engineering comes from graduating GE’s Engineering Leadership Program, where he designed wind turbines and biofuel power plant engines. Michael’s passion for design is energy efficiency and green technology.