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With Monsoon Season upon us, we are finally starting to see some measurable rain here in the desert. With infrequent rain and water a precious resource, how do we maintain our healthy gardens without wasting water? We here at Rosie on the House turn to one of the experts, Greg Peterson of The Urban Farm to provide his take on water-saving ways to grow your desert garden:

“Rain, rain, go away. Come again some other day,” the song lyrics say, but here in the desert my mantra is, “Catch it while you can!”

I often get quizzical looks when I begin to talk about rainwater harvesting at the Urban Farm, soon followed by the question, “Hey, we don’t really get enough rain here to do any harvesting, do we?”

The fact is, for every 1,000 square feet of surface area from which we collect rain in Phoenix, we can harvest over 4,000 gallons of water per year. In “desert speak,” that’s a lot of water!

When I first happened upon the notion of rainwater harvesting, almost three decades ago, I couldn’t wrap my head around the concept of how to store all the water I was going to collect. Then through a series of classes I learned that storing rainwater in containers is just one possibility. The other is to design collection systems to deliver the rainwater precisely where we want it, such as to my thirsty fruit trees. I use both options here at the Urban Farm.

My rainwater-harvesting tank is the above-ground variety that holds 700 gallons and, of course, is covered to mitigate evaporation and pesky mosquitoes. The rainwater is collected from the asphalt shingle roof of my home and stored for use during the really dry parts of the year. The tank water is directed as needed to a part of the yard where it will be most useful. If, like me, you have an asphalt roof, the caveat is to never use the collected rainwater on your vegetable garden, only on your trees.

For those of you who are looking for a simpler solution, a five-gallon bucket or a 55-gallon drum can be used to collect the rainwater from your downspouts. Although these options are easy to set up, they are more labor intensive over the long run as they involve personal effort to collect, cover and then distribute the water.

My personal favorite mechanism for ease of use is the downspout collection system I’ve set up to deliver rainwater directly to my orchard of 10 fruit trees. The rainwater runs off the roof, down the gutters and into a pipe that carries it to the orchard. It’s a simple solution and virtually never needs maintenance. Plus there are no storage issues because the water goes directly into the ground.

Now to the option of greywater, which is defined as any water that runs down the drain of your bathroom sinks, showers and clothes washer but does not include “blackwater” from your toilet or kitchen sink. Simply by rerouting all of this greywater to the landscape we can cut down on the amount of water we use on a day-to-day basis. The trick is to figure out how to get the water from inside our homes to our yards.

One way to redirect greywater is to replumb your sinks so that they run to the outside rather than into the sewer or septic tank. This can be a challenging job for even the most skilled among us, but is a great option when building a new home or remodeling. Other alternatives are as simple as hanging a hose over a tree limb to create your own outdoor shower. This is not, however, for the faint of heart—unless you also design a system to warm the water with the sun.

At the Urban Farm we have integrated greywater harvesting into the remodeling of our outdoor patio by designing the outdoor wet bar and shower to drain into the landscape. You can apply this same approach in your individual circumstances so that your water serves double duty by first running through your sinks, showers or washers, then irrigating your landscape.

Greywater is legal in the State of Arizona. Simply follow the 13 best practices outlined by the Arizona Department of Environmental Quality (ADEA) in their document called Using Greywater at HomeWhen it comes to designing and installing your greywater system, the premier book on the subject is Create an Oasis with Greywater by Art Ludwig. He outlines the many systems you can build and includes great graphics, charts and pictures to assist any do-it-yourselfer. For rainwater collection, Brad Lancaster has written a great book called Rainwater Harvesting for Drylands and Beyond that is the premier manual on creating your own solutions.

Both rainwater and greywater collection systems are simple to use once you understand the concepts. Put them to use in your landscape and you’ll soon be “singing in the rain.”



Farmer Greg say water harvesting is more that just collecting rainwater and a tank: it’s a deep dive into creating a system. Where the water source is coming from and going to, collecting and distribution plumbing, tank, filter and pump, directing where you want the water to go and designing the right system for your needs. It can be simple and inexpensive! You can also reduce your regular water consumption.

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