Rainwater Harvesting, Extreme Edition

Rain barrels are a common sense idea, and I love seeing them pop up at school gardens. Here is one of the barrels at the junior high garden.  It holds 60 gallons— 60 gallons that will not come from the spigot and will be replenished repeatedly this year (after we water the garden following dry spells or use water for the compost bin).

photo by Jeff Holt

It’s an ancient and necessary idea: catching our own rainwater and using it when we need to irrigate.  Quite simply, every ounce of precious rainwater captured, stored and later used for irriation is an ounce of precious potable water saved.  It’s a no-brainer technology, but as we know, when natural resources are cheap, convenient and plentiful, we often don’t invest the time, money or energy into smart alternatives.  It’s clearly high time for all us—especially drought-plagued regions— to re-think this.

For this reason my Garden Club co-president and I attended a water catchment workshop at our local library.  We were wriggling out of our seats with excitement, and when the talk concluded, we persuaded the presenter (Rosalind Haselbeck of http://www.buildinggreenfutures.com) to walk up to our elementary campus and advise us.  Where should a system go?  How big could it be?  How much would it cost?

I then went looking for grant money.

Two proposals were accepted.  We received $1,000 from San Diego Agriculture in the Classroom (a program of the San Diego Farm Bureau) and $3,500 from San Diego County Supervisor Diane Jacob’s Neighborhood Reinvestment Program.

The system was installed in the spring, and we cut the ribbon this fall.  (The grant money has also paid for educational signage.)  To our knowledge, it is the largest rainwater harvesting project on a school campus in San Diego county. Together the cisterns hold 3,000 gallons of water.

Two cisterns hold 1,500 gallons each; a pump in the middle attaches to a garden hose

County Supervisor Jacob waters the kindergarten winter vegetable bed with rainwater pumped from the cisterns

The cisterns sit discreetly behind our gazebo

Installed gutters catch rain that falls on the roof of the maintenance building adjacent to the garden. (The roof is large, hence significant surface area to catch water–as such, even a modest rain yields a lot of water.  There are cool formulas for this which are easy to find–I won’t bog down the blog with math right now.) Pipes direct the water into the top of the tanks.

Gutter screens keep out major debris.  A “first flush diverter” drains off the first catch of rain (thus washing the roof for a cleaner collection).  A settling J-inlet in the large tank further traps sediment.  (The water is not drinkable—the system has these features to ensure we are storing clean water.) The tanks are dark colored to prohibit algal growth.  Excess water is drained off through an overflow pipe which you can direct wherever you’d like.

It is the end of the December, and the tanks are full.  This past week I needed to do some watering. (It has been cold but very dry.)  I was delighted to find that using gravity-fed pressure ALONE, I could get sufficient water pressure to the far end of the garden.  And after an hour of watering, I could barely see the rain gauge budge.  All of that free, untreated water just coursing through the hose to nurture our garden—pretty amazing!  And now I’ve freed up some space in the cisterns for our next rain, thus catching more water for our next dry spell…

If you are in the San Diego area and would like to see the system in person, please contact me and I will arrange a tour!

6 thoughts on “Rainwater Harvesting, Extreme Edition

  1. I feel so happy tp learn about what is going on at the school gardens. Having had two daughters that grew up at a school with a school garden I can say that this is work that stays with children into adulthood. Thank you for your time and effort!

    • Part of the reason that I’m doing this blog is that I have learned A LOT in the process of working with this garden, and I want to pass it on—-so I’m glad you’re learning too! There is so much potential for rainwater harvesting. I heard of a school in North Carolina that uses rainwater to irrigate their sports fields, landscape their campus and even flush their toliets!

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