Excerpt: 'Rainwater Harvesting'
Catch rain where rain falls.
—East Indian proverb
I love the rain! I love to drink it, sing in it, dance in it, bathe in it. Of course that's only natural; our bodies are more than 70% water. You and I and everyone else—we're walkin', talkin' rain.
Rain is the embodiment of life. It infuses water into our springs, rivers, and aquifers. It cools us, greens the land, and nourishes the plants that feed us. It cleans the air, washes salts from the soil, and makes the animals sing.
Yet, the world's supply of fresh water is finite. Less than one half of one percent of all the water on Earth is fresh and available. The rest is seawater, or frozen. Our supply is renewed only through precipitation, a precious gift from the sky that falls as droplets, hail, or snowflakes, and then flows over the landscape as runoff. In this book, I refer to the gift as "rainwater." And the gift is ripe for harvesting.
Rainwater harvesting captures precipitation and uses it as close as possible to where it falls. The process mimics intact and healthy ecosystems, which naturally infiltrate rainwater into the soil and cycle it through myriad life forms. Instead of sealing and dehydrating the landscape with impervious pavement and convex shapes that drain the gift away, as most modern cities, suburbs, and home landscapes do, harvesting accepts rain and allows it to follow its natural path to productivity.
This book provides you with a simple series of integrated strategies for creating water-harvesting "nets" which allow rainwater to permeate and enhance our landscapes, gardens, yards, parks, farms, and ranches. Small-scale strategies are the most effective and the least expensive, so they are emphasized here. They're also the safest and easiest to accomplish. They can empower you to become water self-sufficient.
The benefits are many. By harvesting rainwater within the soil and vegetation—in the land, or in cisterns that will later irrigate the land, we can decrease erosion, reduce flooding, minimize water pollution, and prevent mosquito breeding (within water standing on top of the soil for more than three days). The process also generates an impressive array of resources: It can provide drinking water, generate high quality irrigation water, support vegetation as living air conditioners and filters, lower utility bills, enhance soil fertility, grow food and beauty, increase local water resources, reduce demand for groundwater, boost wildlife habitat, and endow us and our community with skills of self-reliance and cooperation!
My Rainwater-Harvesting Evolution
In 1994, my brother Rodd and I began harvesting water in our backyard by digging, then mulching a basin around a single drought-stressed sour orange tree. We graded the soil around the basin so runoff from the surrounding area, and the neighbor's roof would drain to the tree. The results amazed us. After a single rain, the tree burst out with new leaves, a dreamy show of fragrant blossoms, and an abundant crop of fruit that was soon converted into tasty marmalade and "orangeade" by family, friends, and neighbors. That was ten years ago, and we've since kept our irrigation of that tree to just three supplemental waterings per year. Yet we live within the Sonoran Desert where annual rainfall averages just 12 inches (304 mm), and most folks water their citrus trees at least once a week.
With the citrus tree flourishing, we decided to mimic its success and make rainwater the primary water source for all our outdoor needs. Using methods described in chapters 3 and 4, and more in depth in volume 2, we created and planted undulating water-harvesting earthworks throughout our once barren yard. The rain then gently soaked into the soil, soil erosion ceased, and verdant life began sprouting everywhere. We planted shade trees that grew tall around the house, cooling summer temperatures enough for us to eliminate our evaporative cooler (improved insulation, painting the house's exterior white, and passive ventilation also helped). We then boosted the growth of these trees still further using greywater recycled from the drains of our home's sinks, shower, and washing machine. Our daily municipal water use dropped from the Tucson residential average of 114 gallons (431 liters) per person per day1 to less than 20 gallons (75 liters) per person per day, and our water and electric bills plummeted. This earned us five visits from workers at both the water and electric utilities because they were sure our meters were broken.
We wanted to do more. Every time it rained our street turned into a river, fed by runoff from neighborhood roofs, yards, and pavement. We redirected that runoff to 19 young native trees we planted in the barren public right-of-way adjacent to our property. These low-water use trees now sing with nesting songbirds and offer a beautiful shaded canopy for passing pedestrians, bicyclists, and motorists. Water that once flowed away now supports trees that filter pollutants carried in the road's runoff as they shade and cool the street (see the chapter on reducing hardscape and creating permeable paving in volume 2 for more details). Mosquito populations have plunged because water no longer stands in puddles, but is instead soaked up by spongy mulch and taken up by plants.
Our lot was once hot, barren and eroded, with a house that could only be made comfortable by paying to mechanically alter its climate. Now our yard is an oasis producing 15 to 25% of our food, and after growing trees and installing solar panels to power fans, we no longer pay a cent to heat and cool our home (keep in mind we are also the type that will put on a sweater before firing up a wood stove). We've switched from contributing to neighborhood flooding to contributing to neighborhood flood control, and our landscape enhances local water resources instead of depleting them. On our 1/8-acre (0.05-ha) lot and surrounding right-of-way we currently harvest annually over 100,000 gallons (454,600 liters) of rainwater within a 1,200 gallon tank, the soil, and vegetation, while using less than 20,000 gallons (75,600 liters) of municipal groundwater for our domestic needs and landscape irrigation in dry spells. Four-fifths of the water we now use comes from our own yard, not from city supply.
When friends and neighbors drop by they see the potential of water harvesting and learn how to do it themselves. Many then go home and spread the "seeds" by setting up work parties and creating their own rain-fed oases. That, in essence, is my vision: harvest rainwater within our own yards and neighborhoods, encourage emulation, enhance rather than deplete our water resources, and improve the lives of everyone in our community.
Excerpted from Rainwater Harvesting for Drylands and Beyond, Volume 1 By Brad Lancaster © 2006, 2008, www.HarvestingRainwater.com. Reprinted with permission.
Copyright 2023 NPR. To see more, visit https://www.npr.org.