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Rainwater harvesting is a great way to conserve municipal water, reduce utility bills, and create a backup water supply or—like our system here at 36-Acre Wood—even a primary water supply for your entire home. Whether you want to use rainwater for drinking, gardening, or other household needs, you might have questions about how to get started, maintain your system, and ensure water quality. In this post, I’ll address some of the most common questions I get about rainwater harvesting for both potable and non-potable uses and recommend some products we use for our system.
FAQ 1: What Is Rainwater Harvesting?
Simply put, rainwater harvesting for home use is the process of collecting and storing rainwater. Systems range from basic setups like barrels under gutters and downspouts to more advanced systems with larger cisterns, filtration, and disinfection for potable water. It’s a versatile solution for reducing reliance on municipal water and supporting sustainable living, even in arid areas like here in Northern Arizona. We've been able to meet all of our daily and annual household and garden water needs with rainwater collected from our house and workshop roofs, stored in three partially buried and interlinked 5,000-gallon tanks (pictured here) and several overflow barrels and water totes.
FAQ 2: Is Rainwater Safe for Drinking?
Rainwater can definitely be safe to drink (potable), but it should be properly collected, filtered, and treated if that's what you'll use it for. Contaminants like debris, bird droppings, and roof materials can all affect water quality, so a multi-step filtration system ensures the water is clean and safe for consumption. Have a look at our filtration and disinfection units here.
On a related note: What is the best roofing material for a potable rainwater collection system?
The answer:
Metal roofs with an enamel finish are often considered the best choice. They provide high collection efficiency and minimal contamination. There are also other suitable roofing materials for rainwater harvesting. Here's a helpful page on Harvesting Rainwater from Roofs from the University of Idaho.
Recommended Products for Potable Use:
First Flush Diverter: After the rainwater passes through gutter guards and downspout screens, you can use a first flush diverter (aka roof washer) to further prevent contaminants from the initial rainfall from entering your system. You can buy a first flush diverter kit or make one yourself. (See one of ours pictured here.)
Water Filters: After entering your home, the rainwater can pass through a filtration system to capture any dirt, sand, silt, dust, rust, and other small particles that made their way past the first flush. A filter system can also eliminate cloudiness, bad taste, and odors. They're effective on VOCs like pesticides, herbicides, and industrial solvents. We use the US Water Big Blue Dual Filtration System (pictured above), which is mounted in our utility room.
UV or Quantum Disinfection: After the filters, a disinfection unit kills bacteria and viruses. We use the Pulsar from U.S. Water Systems (pictured above), which doesn't require UV light or power.
FAQ 3: How Do I Filter Rainwater for Potable Use?
This is a partial repeat of FAQ 2, but... To make rainwater safe for drinking, you can use a combination of filters and purification methods in this order:
Screen out roof debris: Install mesh screens on your gutters and downspouts.
Use a first flush diverter: Direct initial dirty water away from your collection system.
Apply fine filtration: Add a filtration system in your home to remove smaller particles.
Sterilize the water: After filtration, use UV purification or non-electric quantum disinfection to kill microorganisms.
Recommended Products:
Mesh Gutter Guards and Downspout Filters: Prevent leaves and debris from clogging your system. Check out a variety of gutter and downspout screens on Amazon and choose the size and type to fit your gutters.
First Flush Diverters: Remove the initial "dirty" water from each rain before it enters your tanks or barrels by using a roof washer kit or make your own DIY first flush diverter.
Carbon Filters for Rainwater Systems: There are a number of effective options, like the US Water Big Blue Dual Filtration System (which is what we use) and the iSpring WGB32BM.
Disinfection Filters: You can use an Ultraviolet Light Disinfection System or non-electric quantum disinfection with a unit like the Pulsar.
FAQ 4: Can I Use Rainwater for Non-Potable Purposes?
Absolutely! Non-potable uses are the most common applications for rainwater harvesting. Examples include:
Gardening and Irrigation: Rainwater is naturally soft and chemical-free, making it ideal for plants.
Washing Vehicles: Soft rainwater prevents water spots.
Flushing Toilets: Use collected water to reduce household water consumption.
Recommended Products for Non-Potable Use:
Hose Attachments for Rain Barrels: Make watering plants easy. Check out the Rain Barrel Diverter Kit with a 3/4 Inch Spigot Kit and Bulkhead Fitting.
Pressure Boosting Pumps: For a smooth water flow, you can use a transfer pump like this one from VEVOR.
FAQ 5: How Much Water Can I Collect?
The amount of rainwater you can harvest depends on your roof size, rainfall (and snowfall) in your area, and the efficiency of your system. On average, one inch of rain on a 1,000-square-foot roof yields about 600 gallons of water. You can use a rainwater collection calculator like this one from BlueBarrel Systems to estimate potential yields.
FAQ 6: Do I Need a Permit to Harvest Rainwater?
Rainwater harvesting regulations vary by location. In some areas, permits are required, especially for large systems (that's the case here in Coconino County, AZ, where we have a permitted potable rainwater collection system). Check your local government’s guidelines or water board for specifics.
FAQ 7: How Do I Maintain My Rainwater System?
Proper maintenance ensures your system remains efficient and hygienic. Here’s a checklist:
Clean Gutters Regularly: Prevent debris from entering your system.
Flush Out Tanks: Rinse barrels and cisterns annually.
Replace Filters: Change filters as per the manufacturer’s recommendations. We recommend U.S. Water Systems for replacement filters for a variety of units.
FAQ 8: What Are the Best Storage Containers for Rainwater Harvesting?
Common options include barrels, cisterns, and water cubes like IBC totes. Each has pros and cons: Recommended Products:
Rainwater Barrels: Barrels are generally affordable and easy to install. Options like this Happygrill collapsible barrel with spigot and the BPA-free Blue Water Barrel are durable and effective, and you can add a spigot to any other barrel you choose. If you're not harvesting rainwater for potable use, you can use a wider variety of containers for collection and storage.
Water Totes: These cube containers are portable, durable, and space-efficient. We use stackable IBC totes for some of our overflow storage (you can often find used totes for sale locally—just be sure to find out what was in them beforehand) and then use IBC tote covers to help prevent algae from forming inside the cube and prevent freezing also (see the photo below, showing our covered tote for collecting rainwater off our greenhouse).
Polyethylene Storage Tanks: For larger-scale collection and greater storage capacity like we have and potable use, we recommend vertical tanks like this one from Norwesco. They come in a range of sizes in black or green, limiting light penetration and reducing the growth of water-borne algae.
FAQ 9: How Do I Winterize My Rainwater System?
You can protect your system from freezing by:
Draining or insulating small barrels.
Insulating and/or partially burying large tanks or cisterns. (If you want to bury a tank completely, be sure to get one that's designed for that purpose.)
Using tank heaters or de-icers.
Our large, partially buried polyethylene tanks with their outlets below the frost line don't tend to freeze due to the volume of water and the frequently sunny winter days. While they do sometimes get a layer of ice on the top of the water during occasional stretches of cloudy, extremely cold weather, that ice usually melts quickly and has never presented a problem in our system.
Recommended Products:
Barrel Covers: You can try a black barrel cover or reflective bubble insulation. We've had luck with both, but even most of our coldest days are sunny.
Floating De-Icers: The Farm Innovators Floating or Submergible Heater is effective for larger tanks.
Here's more detail on how to keep rainwater barrels from freezing.
FAQ 10: What Should I Do About Water Tank Overflow?
Depending on your needs and space, you can create several types of overflow systems. Some work best for gardens, while others are ideal for additional storage. The different types are:
Basic Spillover Overflow: The simplest option, a spillover overflow, uses a pipe installed near the top of the tank or barrel. When the tank fills, the water flows through the pipe, which directs it away from the tank base. (See one of our spillover setups below.)
Secondary Rainwater Storage Overflow: For those who want to capture even more rainwater, a secondary storage overflow system allows excess water to fill another tank. You can connect as many tanks or barrels this way as you want.
Garden Irrigation Overflow: This overflow directs water from your tank to garden beds or plants, making it perfect for anyone creating a self-sustaining watering system.
French Drain Rainwater Collection Overflow: For larger systems or those with significant overflow volumes, a French drain setup disperses overflow into the ground, preventing pooling and soil erosion.
See more details on DIY water tank overflows here.
Simplifying Rainwater Harvesting for Home Use
Rainwater harvesting offers a sustainable way to reduce water consumption and create a more sustainable lifestyle. Whether you’re collecting rainwater for drinking, gardening, or household use, the right tools and strategies can make the process simple and effective.
Explore our recommended products and start building a rainwater harvesting system that works for you—potable or non-potable, it’s a step toward sustainable living. Do you have any other questions about rainwater harvesting or the system we use? Leave a comment below.
Written by Deb Kingsbury
Living on a 36-acre off-grid property in northern Arizona, Deb and her husband Jeremy embrace sustainable living through solar power, rainwater harvesting, and a passive solar home built with recycled polystyrene block. A freelance writer and editor, Deb grows food in raised beds and a greenhouse and is an avid hiker and backpacker. A long-time search & rescue volunteer, she has published two novels and previously homesteaded on the East Coast.
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