open-source rainwater catchment methods and kits

portland, oregon
WATER IS FREE. What's all this stuff falling from the sky? It's called FREE WATER. Let's collect it! We have made it part of our mission to support your water independence. Part of that is helping you to not need us! The culture's problematic business-thinking makes this philosophy seem silly, but being able to afford our products is not and should never be preventative for someone interested in making a difference. We aim to be part of the solution, from every angle.

See our instructions below on how to make a rainbarrel. And don't hesitate to drop us a line with any questions.

[Please note: We assume that you are able to use all of these tools safely, and cannot take responsibility for shop user-error. Wear safety glasses, always.]


How to Build a Rainbarrel

  • Work/garden gloves
  • Crescent wrench
  • Electric drill
  • 7/8-inch drill bit
  • Utility knife
  • 3/16-inch ratchet
  • 3/4", 14NPT Pipe tap
    (The pipe tap is probably the most specialized part you'll need to buy. And the most expensive; usually about $20. It's basically a tapered piece of metal that's made to create threads. At it's widest, it's 3/4 of an inch in diameter. It fits on your 3/16 ratchet.)
  • Propane torch (not critical)
  • A 55-gallon plastic barrel
  • 3/4-inch male brass spigot or boiler drain (hose bibb)
  • A WaterArm or other Diverter
  • Adapter: 3/4-inch male (NPT) thread to 1/2-inch poly barb
  • 5/8 ID vinyl hose
  • Silicon caulk
Please also note: The following method may be applied to other HDPE type plastic containers. The barrels featured here are 55-gallon, food-grade HDPE plastic. Barrels can be found for around $20 on Craigslist or purchased from us (ours are white, as shown). Please strongly consider repurposed barrels (Why?)
There are a few different ways to make a successful, leak-free, long-lasting rainbarrel. We present only one of them here, the one we employ. We find that it is the simplest, less parts & labor intensive, most likely to do yourself version; and, most importantly, it is effective. This tutorial supposes the use of a food-grade HDPE plastic barrel that did not previously contain material hazardous to the health of humans plants animals or earth. Please be sure you comply with this very important rule when sourcing your container. OK, let's get started.

At its most basic, a rain barrel needs three things:
an intake, an overflow, and an outlet.
  • Intake — Some manner of diverting the water from your downspout into the container.
  • Overflow — In an average Portland rain, your 55-gallon barrel will fill up in an hour. Where is that extra water going to go? You don't want it eroding your foundation or getting in your basement. Every system must have a plan for where the water goes after the container has filled.
  • Outlet — usually a spigot at the bottom of the barrel.

The intake can be a simple hole in the top of the barrel with a downspout pointed at it. At Contain Rain, we prefer our downspout diverter (called the "WaterArm"). This one piece combines the intake and the overflow, and your intake will be a simple hose running from the waterarm to the barrel. It is made out of 80% reclaimed plastic parts (from the Rebuilding Center). You can make this yourself, but you might find that ours is cheaper anyway, since we source in bulk.
(Learn more about how the WaterArm works.)

With a downspout diverter like the WaterArm, water flows into the barrel until the barrel is full and then back-flows up the same device, where it's automatically directed back down the downspout (to where-ever you have it aimed, either the sewer or your on-site rain garden and/or French drain.)

To set up your rain barrels to be compatible with any retail downspout diverter (including the ContainRain WaterArm), you must remember barrel must be air tight. Put those caps on as tight as humanly possible. The only tool we've found for this (aside from making or buying a specialized tool) is a crescent wrench open and turned on its side.

Let's install the 3/4" inlet barb for the WaterArm first, since it's easy.
  • Remove one of the bunghole caps.
  • Hold the bunghole cap in a vice, wrench or gloved hand.
  • Turn on the propane torch and blast it right in the center of the bunghole cap for a 2 seconds. This simply softens the plastic, but isn't critical. Don't cut yourself!
  • Take your utility knife and cut a hole out of the center.
  • Screw your cap back onto the barrel. Use your wrench to screw it it on there as tight as humanly possible. While you're at it, make sure the second bunghole cap is on as tight as humanly possible.
  • Take your barbed plastic adapter, put a ring of caulk around the outer edge of the threads and screw it into the bunghole cap with the hole in it. Use the actual threads that already exist on the bunghole cap. Wrench it on there even more. Done.

Now it's time to install the spigot. Roll up your sleeves. The outlet is a simple 3/4-inch brass male-threaded spigot installed at the bottom of the barrel. These spigots can be found at any hardware store. They can be a hose bibb, or you can use a boiler drain (the difference is that the boiler drain requires only a single turn to fully open. This minimizes the strain on the barrel/outlet coupling. We recommend that you install the outlet approx. 4" above the bottom of the barrel. Usually there are seams that you can use as guides.
  • See how there's a seam running vertically on two sides of the barrel? Pick the seam that's OPPOSITE the side of the inlet.
  • Trace your finger down this seam until you're about two inches from the bottom of the barrel. See how there's a place there where two seams cross? Grab your drill and put a 7/8-inch hole right there. (Be careful when you drill, make sure that the drill is at full speed and SLOWLY lower the bit into the plastic. If you move to fast, the drill will catch, fly out of your hands, and ruin your hole!)
  • Using your utility knife, clean up the outside of the hole so there are no frayed plastic edges.
  • Grab your pipe tap and put it on the ratchet. Make sure the ratchet is set to "forward".
  • Using a keen eye and steady hands, ratchet the pipe tap into the hole you just made in the barrel. This will widen the hole AND add threads. You don't want to tap all the way to the widest portion of the pipe tap. Go approximately 3/4 of the way up the pipe tap. So, you'll leave the hole a little smaller than 3/4 of an inch.
  • Grab your brass spigot. (Optional: Put on your leather gloves. Fire up the propane torch and heat up the threads for, oh, 4 seconds. This helps with getting the plastic to accept the threads.)
  • Using your same steady hand, and your same keen eye (or the other eye, I don't care), twist that brass spigot into the hole. It won't be easy! Make certain that the threads are taking STRAIGHT or the spigot will not seal. If you ruin the threads putting the spigot in sideways, then you've ruined your barrel as well.
  • Once your brass spigot is in and aligned properly, you'll need to crescent-wrench it the rest of the way on.
  • Before you tighten it the last quarter, carefully place a small bead of caulk around the top of the threads. This is not necessary, but will help to fill in any aberrations you may have in the plastic threads. (Be careful not to tighten the spigot too many revolutions or you will screw it right through the barrel. You only have around a 1/4" of HDPE to work with! When it is complete, however, you should not see any of the spigot threads above the surface of the barrel.) Rest assured, that sucker is really on there.
And just how will this not leak, you ask? The operating principal is that we use the constitution of the plastic, namely its plastic/elastic properties, to our advantage... The interior diameter (ID) of the spigot is 3/4". The outer diameter (OL) is just shy of 1". We drilled a 7/8" hole in the barrel and tapped it with a 3/4" tap. This leaves the spigot smaller than the threaded hole by about 1/16". What happens is as you wrench the spigot on, the plastic squeezes the threads and creates a very reliable seal. We've found there is no need whatever to mess around with extra couplings on the inside of the barrel, etc. etc.

You're done! Now you know how to install stuff into a bunghole cap, AND you know how to install stuff into the side of a barrel. The rest is just variations on a theme. Enjoy making rain barrels! Let us know if you have any questions. You can thank us by buying supplies from us, sending us pictures of your projects (really, we LOVE seeing your pictures. We'll put them on the "community" section of our website), and sending us testimonials and love letters.