When it comes to gardening, water is life. But why stick to the tap when nature gives us a free alternative?
Rainwater—it’s literally a gift from above, a precious resource in dry climates.
I’ve been collecting rainwater for years, which has cut off a chunk of my water bill.
Let me share the basics of rainwater harvesting, including some tips and tricks I’ve picked up along the way.
Rainwater Harvesting Basics
Setting up a rainwater harvesting system might seem like a big job, but it pays off in both water quality and cost savings.
Before you start, check if it’s legal in your area. It’s usually fine if you’re only using the water for your garden and not for household use.
Rainwater is often better for your garden than tap or well water. It’s usually warmer and doesn’t contain chlorine, which plants kind of hate.
You likely have most of the setup in place: a catchment area (your roof) and a conveyance system (your gutters and downspouts).
The only missing piece is a rain barrel, but more on this later.
Roof Surface
Most roof surfaces, including metal, plastic, slate, and clay tiles, are perfect for rainwater harvesting.
What’s not okay for rainwater catchment systems? Wooden roofs!
Wood shingles are treated with chemicals to make them resistant to fire and rot. Those toxic chemicals can leach into the water and eventually into your soil and plants.
Fun Fact: For every inch of rainfall, you can collect about 0.6 gallons per square foot of roof.
So if your roof is 1,000 square feet, that’s 600 gallons from one good rainfall. Sure, this water gets spread out to all your downspouts, but that’s still a ton of free water for your plants!
Rain Barrel
If collecting water solely for your lawn or garden, you may not need a more elaborate system than a rain barrel.
You can use any durable leak-proof container or an IBC tote (a caged rectangular-shaped tank). You can easily find one in your area or online.
Here’s what you’ll need to make your own:
- A large plastic barrel
- Brass spigot
- Threaded pipe union fitting or washers and nut
- Waterproof sealant
- Mesh screen or landscaping fabric
- Teflon tape
- A drill
- Utility knife
Let’s get to work!
- Drill a hole in your barrel a few inches from the bottom. The hole should be slightly smaller than your spigot or union fitting.
- Install the spigot:
- Apply sealant around the hole.
- Wrap plenty of Teflon tape around the threaded end of your spigot.
- Insert the spigot from the outside.
- Secure it on the inside with a union fitting (or using washers and a nut).
- Let the sealant dry completely. (Refer to the package for the exact curing time.)
- Cut a hole in the lid large enough for your downspout to feed into.
- Cut a piece of mesh screen larger than the lid and place it over the top of the barrel before putting the lid on. It should keep roof gunk and mosquitoes out of your rain barrel.
- Optional: Drill an overflow hole and attach a hose to it. You can feed all the excess water into another barrel instead of letting it run off.
I keep my barrels on the north side of my house. They get less intense sunlight there, which means less algae growth.
Dark or colored barrels also resist algae better than clear ones.
Pro Tip: Place your barrel on a sturdy platform. The extra height gives you better water pressure, which means faster flow.
Overflow
A heavy downpour can push out a surprising amount of overflow. Use all that excess water to your advantage.
I direct mine towards my perennial plants that need lots of hydration. I use an extra-long hose for this.
Just make sure to point it away from your house or any other buildings.
Is Rainwater Harvesting Legal?
Rainwater harvesting is legal in almost all of the US. Some places, like Arizona, Florida, and Hawaii, even offer incentives to encourage it.
In Kansas and North Dakota, rainwater harvesting is legal as long as you’ve secured a permit for home or outdoor use. A few states are stricter about it.
Water laws differ from state to state because availability varies. But most states follow a rule called “reasonable use.”
This means you can use water as long as it doesn’t prevent others from using it, too.
Luckily, state restrictions mostly cover storage capacity, design, and purpose (potable, non-potable, or outdoor use).
If you live in one of these areas, check your local regulations for specific rules on rainwater harvesting:
- Arkansas
- California
- Colorado
- Georgia
- Illinois
- Nevada
- North Carolina
- Ohio
- Oregon
- Rhode Island
- Texas
- Utah
- Virginia
- Washington
- Wisconsin
Final Thoughts
There you have it—your rainwater harvesting system! Once you start seeing that barrel fill up, you’ll feel like you’ve found the pot of gold at the end of the rainbow.
Just remember to check for leaks now and then, and clean it out occasionally.

Growing up with a mom who filled her home (inside and out) with all sorts of plants, Lisa got her start in gardening at a young age. Living now on her own with a home and yard full of plants (including an indoor greenhouse), she shares all the gardening tips she’s gained over the years.