Harvesting Rainwater

I just read Brad Lancaster’s books, Rainwater Harvesting for Drylands and Beyond, Volume’s I and II. They are brilliant and completely relevant to everyone regardless of where you live. Volume I gives a broad overview of the why’s and how’s along with a ton of great examples. Volume II gets into the nitty gritty details.

Basic premise – water coming from the sky, known as precipitation, is typically directed away from homes, off of property, and into the nearest sewer drain. Instead Lancaster suggests various techniques in order to capture the precipitation and put it to work growing food and creating lush landscapes – thus utilizing less municipal water.

Some of the ideas he presents are earthworks – basically changing the elevation around your property in order to direct water to plants. For example creating a basin around a tree, or making earthen fish-scales across a slope to slow and capture water to feed an orchard. In the examples presented all pathways, driveways and sidewalks are at the highest elevation, and other features, that need water, are set lower so that water will naturally flow into them. It makes sense.

Other subject matter includes grey water recycling  – did you know that the typical household uses 100-200 gallons/day. Cisterns used to store rooftop water is another subject. In using the mathematical formula provided in the book I learned that I could harvest 9600 gallons/year from my rooftop.

Another really important point the author makes is having good soil with plenty of mulch, and ground covers  – this will allow for water to better infiltrate through the soil versus just run over it and into the sewer. I can vouch for this in my front landscaping. With the addition of ground-cover plants (think wild strawberry, verbena, thyme) and trees, the area already looks so much better and consumes far less water than less developed areas of my yard.

So as much as I love this book and plan to heed it’s wise advise it pained me to read.. you see I have managed to do the direct opposite. My garden beds all sit up higher than the surrounding ground. There is no chance of runoff from the sidewalk, driveway or paths to permeate the plants. In fact the entire southern half of my yard is in raised beds. Turns out I should be doing the opposite. After reading this book.. I had to start over with the permaculture mapping project I am making for my property – Plant guilds had to be relocated to portions of the yard that will have access to water. Basins around the guilds had to be created to capture and hold the water. And one of my favorites ideas – a trench down the fire-strip, allowing the sidewalk water to flow down into, thus watering the trees and drought tolerant plants I have planned for the area.

I discovered another great idea in a different book, Gaia’s Garden, written by Toby Hemenway, references the Zemach family. Their property in New Mexico is a lush and waterwise example of permaculture design, in which no municipal water is utilized in the landscaping. One feature is a circular lawn with a subtle change in elevation creating a dish shape into which rainwater is directed to flow through to the center.

This is a big paradigm shift for me and my brain is still buzzing on how I can implement some of these ideas into my yard. Important since I live in a fairly arid climate with only 30 inches of precipitation per year.

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