Rainwater Harvesting in Arizona: How We Live Off the Rain in the High Desert
- Deb
- Apr 8
- 5 min read
Disclaimer: I get a commission for purchases made through some of the links in this post.
Living in northern Arizona, where water is precious and often scarce, we've found an abundance in our skies. Through rainwater harvesting, we collect, filter, and use only the water that falls on our roofs, including the house, the workshop, the greenhouse, and a few other small structures on the property—enough to meet all our home and garden needs, year-round.
In a region known more for drought than downpours, this may sound impossible. But we’re here to share that not only is it possible, it’s practical, sustainable, and (because people have asked us) completely legal.
What Is Rainwater Harvesting?
Rainwater harvesting is the process of collecting and storing rainwater and snow(melt) that falls on rooftops, land surfaces, or other catchment areas. In most home systems, the water is captured from the roof via gutters and downspouts and directed into storage tanks or cisterns. With proper filtration and treatment, this water can be used for everything from irrigation to drinking and bathing.
In Arizona, where every drop counts, rainwater harvesting has become both a survival strategy and a lifestyle choice.
Is Rainwater Harvesting Legal in Arizona?
Yes, rainwater harvesting is completely legal in Arizona. In fact, the state encourages it. Arizona passed legislation in 2012 clarifying that individuals may collect and use rainwater on their property.
This contrasts with some other western states like Colorado, which, until recently, had strict restrictions on rainwater collection. However, laws are shifting as drought becomes more common in more places and water resources dwindle.
It’s always important to check local and state regulations and building codes, especially if you're installing a large-scale system or plan to use the water for potable purposes.
Can You Really Collect Enough Rainwater in Arizona?
Yes, you can—even in an arid climate like northern Arizona. We’re proof of that. With strategic system design and efficient water usage, we’re able to live entirely on rainwater we collect ourselves.
Here’s how we do it:
Roof Catchment Area: Between our house and shop/garage, our metal roof area is about 3,000 square feet. For every inch of rain that falls (and for every 10 inches of snow), we can collect around 1,869 gallons of water. Over the past few years, we've recorded about 13 inches of liquid precipitation (some of that being melted snow) at our home.
Storage Capacity: We have an interconnected cistern system with a capacity of over 15,000 gallons. This ensures we can store enough during the rainy seasons (i.e., the summer monsoons) to get through the drier months.
Filtration & Purification: After collection from our roofs, water passes through first flush diverters (aka roof washers) before entering storage tanks and then through a filtration system and a quantum disinfection system inside the house for potable use, which doesn't require a power source or UV light (other than the pump, which, for us, is a Grundfos Scala2).
Water Conservation Habits: From low-flow fixtures to mindful gardening with the use of rainwater tank overflow and mulch, every choice we make is designed to stretch every drop.
Over the past few years here at 36-Acre Wood, according to our simple rain gauge, we've received around 13 inches of rain and snowmelt, most of it concentrated in the months of July through September. (Up the road, about 15 miles to the north and south, the averages are more like 20 and nine inches, respectively.) With good planning and enough storage, we’ve haven't had to supplement with hauled water. (We have no municipal water where we live.)
Benefits of Rainwater Harvesting in Arizona
There are many benefits to harvesting rainwater, especially in Arizona:
Reduces Demand on Limited Water Sources: Many areas in Arizona rely on overdrawn aquifers or imported water from the Colorado River.
Improves Landscape Health: Rainwater is free of salts and chemicals found in some tap water, making it ideal for gardens.
Saves Money: While there's certainly a cost to installing the system in the first place, reducing or eliminating your water bill can lead to long-term savings, especially in rural areas where water must be hauled in.
Increases Self-Sufficiency: In a changing climate, relying on your own water source can provide peace of mind. It's also super-satisfying!
Helps with Flood Control: Harvesting reduces runoff and erosion around buildings during heavy rains.
How to Set Up a Rainwater Harvesting System
Whether you’re starting small or going all in, a basic rainwater harvesting setup in Arizona includes:
Catchment Surface: Your roof. Metal roofs are ideal, but others work, too.
Gutters and Downspouts: To channel the water.
First Flush Diverter: Also known as a roof washer, it helps discard the first flow of water that may carry debris, like bird droppings or dust.
Storage Tanks or Cisterns: Sized according to your expected use and rainfall.
Filtration and Disinfection System: Especially if you're using water indoors for potable purposes.
Pump and Pressure System: To deliver water where you need it.
Note that if you’re planning on using the water indoors, you may want to consult with a professional on filtration and plumbing code compliance. For example, here in Coconino County, Arizona, first flush diverters are required for potable rainwater harvesting systems. Ours was installed during the initial home-building process, so we followed the code to pass the inspection.
If you're interested in building a potable rainwater harvesting system for your home, you can check out ours (tips included) as well as how to make your own DIY first flush system.
Potable vs Non-Potable Rainwater Use
In our home, we use rainwater for both potable (drinking, cooking, bathing) and non-potable (toilets, laundry, irrigation) purposes. This is possible because we invested in a proper multi-stage filtration system that includes:
If you’re only using rainwater for non-potable purposes like gardening, a simpler system can suffice. That said, potable rainwater systems are becoming more common, especially in rural areas like here in Northern Arizona.
Rainwater Harvesting Incentives in Arizona
Some Arizona cities and counties offer incentives and rebates to support water conservation efforts, including harvesting systems. For example:
Tucson Water offers up to $2,000 in rebates for passive and active rainwater harvesting systems.
Flagstaff and Prescott have educational programs and resources to help residents get started.
Check with your local water utility or county extension office to see what’s available in your area.
Getting Started: Tips for Success
If you’re inspired to start harvesting rainwater in Arizona, here are a few tips:
Start with your goals: Are you aiming for full off-grid use or just garden irrigation?
Understand your rainfall: Know when and how much rain typically falls in your area.
Maximize storage: You’ll want enough tank capacity to get you through dry spells.
Equalize multi-tank systems: If you're collecting in more than one cistern and linking them together, it's important to keep the overflows on all tanks as close to the same elevation as possible. Learn more about that here.
Conserve water: Combine rainwater harvesting with smart water use, including low-flow fixtures, DIY rainwater overflow collection or diversion, and gray water systems, to extend your supply.
Educate yourself: Resources like the Arizona Department of Water Resources and local groups like Coconino County's Sustainable Building Program can help. (We're happy to help, too. Just leave a comment or contact us with any questions.)
Final Thoughts
Rainwater harvesting in Arizona isn’t just a pipe dream—it’s a smart, sustainable reality. Living entirely off rainwater in northern Arizona has given us a deeper appreciation for our natural resources and a stronger connection to our environment. With a little planning, the right equipment, and a mindset of stewardship, anyone in the Southwest can take advantage of the rain and create a thriving home and garden—no matter how dry it seems.
Do you harvest rainwater in an arid area? Please share your experience and suggestions below.
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