Rainwater Harvesting At a Glance

This started out as a blog on installing a rain barrel, but as I looked at information from various sources, it became clear that there’s no way I could do justice to the topic of rain barrels, let alone rainwater harvesting, in a single blog, and there are so many good resources online covering every type of water harvesting and storage vessels imaginable.  So, here’s a high-level view of residential water harvesting, and a bunch of links at the bottom of this blog, if you want to learn more about rainwater harvesting.  Gray water harvesting is another way to save water, but it may be regulated differently than rainwater, so be sure to check before investing in any water harvesting hardware.

Residential rainwater harvesting can be as simple as diverting water from a downspout into a rain barrel, or even a chain of rain barrels.  Rain barrels range in size from about 50 to 350+ gallons.  Above ground water storage tanks vary in material and construction and hold from 100 to 75,000 gallons and higher.  There are underground water storage tanks as well, primarily plastic, that range in capacity up to over 2600 gallons each.  The water entering any of these storage vessels must be filtered to remove solid debris and covered so that mosquitoes cannot lay their eggs.  During our torrential thunderstorms, a rain barrel water harvesting system can easily be overwhelmed by the volume of water being diverted into the system over a very short span of time.  It is estimated that an average size roof can deliver ~1000 gallons of rainwater for every inch of rain that falls. Questions for potential residential water conservationists include:

  • What types of water harvesting are permissible in your locality?
  • How do you plan to use the water you’ve harvested?
  • How much do you want to invest in water storage?
  • How much water can you harvest, and store based on your collection methods and storage capacity? 
  • How will you preserve the quality of the harvested water in the event it is stored for an extended period?
  • What is the impact to your specific environment or your water bill if you implement water harvesting?

    Two downspouts feed into this medium capacity tank, which can bebset up to use the rain barrel beside it for overflow.

    Two downspouts feed into this medium capacity tank, which can set be up to use the rain barrel beside it for overflow.

Most of us who water with a hose don’t really have a good idea of just how much water we use outdoors, but a glance at your water bills will provide a decent estimate.  The average American family of four uses 12,000 gallons of water a month.  That includes outdoor watering.  When you water outdoors, you are likely using two gallons of water per minute of watering activity.  So, for every hour of outdoor watering, that’s 120 gallons of water.

When I lived in Pennsylvania, I had a 2000+ square foot vegetable garden, situated in the corner of a hay field, with no access to running water.  I was already in the habit of keeping plastic jugs full of water in my basement because I had no running water during power outages, which, during winter storms, could last a lot longer than I care to remember.  During the hottest part of the summer, I would load up my trusty old Subaru with 70-100 gallons of water and an old Irish Setter, drive up to the hay field, and water the garden.  During July and August that could be every day.  Here in Georgia, the need to water almost daily could include the latter part of May, all of June, and at least part of September as well.  Watering outdoors using containers of known volumes keeps you mindful of how much you’re using, and how much you’ve wasted by watering the driveway or the street with your sprinkler system.  While concrete and asphalt spread like kudzu, it has nothing to do with you watering them.

When setting up a rain barrel, it's useful to place it on a platform tall enough to allow whatever containers you may want to use to withdraw the water under the spigot.

When setting up a rain barrel, it’s useful to place it on a platform tall enough to allow whatever containers you may want to use to withdraw the water under the spigot.

The tangible benefits of installing a rainwater harvesting system vary based on your needs, the rainfall patterns where you live, how much you spend on it, and how well it works.  You really need to assess how much water you’re currently using outdoors and determine whether harvesting rainwater can provide sufficient quantities of water when you need it.  Installing several 100-gallon rain barrels at the downspouts may supply all the water you need outdoors at any given time, but you need to know how much you’re currently using outdoors at different times of the year, particularly during that long hot spell during Georgia’s summer months (which hasn’t been all that predictable the last few years).  Think about how you would change your outdoor watering habits if the only water available to you was rainfall.  It may help you decide which water harvesting options might work best in your situation.

Water storage tanks such as this are more likely to found on farms, and can be placed as needed for relatively convenient access when needed.

Water storage tanks such as this are more likely to found on farms, and can be placed for relatively convenient access when needed.

If installing a rain barrel isn’t feasible, there are alternative ways to harvest rainwater.  Tribal farmers, some of whom only have about the same size plots to grow all their food, herbs, medicinal plants, and cooking fuel that we suburbanites do, have utilized such techniques as furrowing, mounding, terracing, and channeling to encourage water to flow where they need it most.  Even mulching is a form of rainwater harvesting.

One of the oldest forms of rainwater capture is retention ponds.

One of the oldest forms of rainwater capture is retention ponds. By situating them carefully, and uphill, water can be channeled as needed to lower lying areas to irrigate crops or to refill cisterns.

Look at these resources and then decide what works best for you.  Harvesting rainwater, even if it doesn’t eliminate all the outdoor water and treatment costs from your water bill, can make a difference about how you view water.  It is a precious commodity, and we’ve been very, very fortunate to have seemingly unlimited supplies of water.  How much longer that will be the case is uncertain, but it will definitely be impacted by a number of factors, including how much we do to conserve and protect our water resources.

Resources:

https://water.usgs.gov/edu/qa-home-percapita.html

http://rwd3rogers.com/documents/331/Household_Water_Usage_Estimates.pdf

https://inhabitat.com/3-ways-to-capture-water-in-your-backyard/

https://dph.georgia.gov/product-approvals

https://www.lid-stormwater.net/raincist_sizing.htm

https://www.motherearthnews.com/diy/build-a-rainwater-collection-system-zb0z1307zsal

https://www.motherearthnews.com/diy/garden-yard/how-to-make-a-rain-barrel-ze0z11zkon

https://www.rodalesorganiclife.com/garden/getting-started-rain-barrel

http://extension.uga.edu/publications/detail.html?number=B1372&title=Rainwater%20Harvesting%20for%20System%20Designers%20and%20Contractors

http://www.walterreeves.com/landscaping/rain-barrels-using/

http://www.walterreeves.com/landscaping/rain-barrel-homemade-1/

http://www.walterreeves.com/landscaping/rain-barrels-commercial-rain-harvesting-systems/

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