Water harvesting

Why use precious potable water on landscape irrigation when harvesting water using a cistern is an alternative?

I’m investing in a new water system for my garden in the Berkshires this spring. Our well, although it furnishes a perfectly adequate supply for our household needs, does not produce enough flow to support garden irrigation. With the increasing frequency of droughts — a feature of our changing climate in the Northeast — I’m finding that just depending on the rain that falls on the garden is no longer enough. Instead, I’m installing a 500-gallon cistern that will be fed by run-off from the roof of our house. Coupled with a gravity-fed drip irrigation system, this should be enough to substantially help our complex of raised bed vegetable gardens through at least the shorter spells of rainless weather.

Such a “water-harvesting” system is still a novelty in the Northeast. It shouldn’t be. Water is an irreplaceable resource, and clean water is in limited supply even in areas such as ours that are blessed with ample amounts of precipitation. We should not be using precious potable water on landscape irrigation, especially while squandering the moisture that falls naturally on our site. It makes no sense to arrange our landscaping so that we pump thousands of gallons of the former to satisfy our lawns and gardens, while we allow the latter to escape as run-off that then overloads our water treatment systems or pollutes the local waterways.

Thomas Christopher

Thomas Christopher

I first encountered water harvesting during trips to the southwestern states 30 years ago, when I was researching a book about water-wise gardening. Recently, I reconnected to that region when I consulted with Greg Peterson, founder of The Urban Farm in Phoenix, Arz.

Greg is a passionate gardener, the creator of “The Urban Farm," a 1/3-acre permaculture food forest that he has created around his home in a residential neighborhood of the city. He believes that current aspirations for sustainability don’t go far enough, that we need to reinvigorate and restore nature rather than just perpetuating it in its current damaged state. Living in a desert locale, a key part of reinvigorating his yard has been to manage water wisely. He told me about how he has done this, while suggesting how I might apply his experience to my very different situation.

Greg says that to control the cost of his gardening, he likes to keep the water harvesting as simple as possible. That is, most of the water that falls on his site he collects in channels that feed a series of shallow basins, which he has filled with wood chips. Around each of these basins he has planted fruit trees, some 70 in all. The water from the occasional rainstorm fills the basins and sinks into the soil at their bottoms, moistening it deeply. The roots of the trees (and potentially other plants) can then tap this subterranean moisture, substantially reducing their need for irrigation. Of course, had he chosen to landscape with native desert plants instead of edibles, as Greg points out, he wouldn’t need to supplement the harvested water at all.

A key to making such a passive rain harvesting system work, Greg explains, is improving the permeability of the soil by adding organic matter. He regularly top-dresses garden areas with a couple of inches of compost and mulches around trees and shrubs 6-inches-deep with wood chips.

Greg has also installed a 750-gallon cistern that he feeds with rain that falls on the roof of his house. He has re-plumbed a bathroom so that the so-called “gray water,” everything except the water from the toilet, is delivered to ornamental landscaping outdoors. He even collects the water discharged from the system that cools his house in summertime to send it to the garden as well. In short, no water is wasted.

I very much doubt that I’ll reach that degree of water conservation, but I do intend to regard the various producers of water in my landscape as potential resources and not just wastes in the future. Thrift, after all, is supposed to be a Yankee virtue. Likewise, my observation when I was researching that book about water-wise gardening is that bringing the landscape into balance with the natural level of the water resources tends to produce much more interesting as well as more efficient display.

For more information about Greg Peterson’s water harvesting techniques, listen to our conversation on the Berkshire Botanical Garden’s Growing Greener podcast at thomaschristophergardens.com/podcast.

Be-a-Better-Gardener is a community service of Berkshire Botanical Garden, located in Stockbridge. Its mission, to provide knowledge of gardening and the environment through a diverse range of classes and programs, informs and inspires thousands of students and visitors each year. Thomas Christopher is a volunteer at Berkshire Botanical Garden and is the author or co-author of more than a dozen books. He is the 2021 Garden Club of America's National Medalist for Literature, a distinction reserved to recognize those who have left a profound and lasting impact on issues that are most important to the GCA. Tom’s companion broadcast to this column, "Growing Greener," streams on WESUFM.org, Pacifica Radio and NPR and is available at his website, thomaschristophergardens.com/podcast.