Take it away, Nathan!
Rain barrels collect rainfall and store it, so that it can be used later. There are 3 main components - The roof, the barrel, and the hose. These are not always a roof, barrel, and hose, but those functions will be present in almost every system (collection, storage, and output). A very common setup is to place barrels under gutters and fill watering cans with the water as needed. Our system will use a small awning as our roof (our gardens and barrels are located a bit away from the house), a barrel for each garden bed, and a soaker hose that runs into each bed from the barrel. Here's how we made the barrels.
Step 1. Procure the barrels. The most important thing about the barrels is that they hold water, and they never held anything bad. In Texas we could get 55 gallon blue plastic barrels from the Coca-cola bottling plant - they were used to transport soda syrup. Up here in North Carolina we got them from an independent farm supply store, and they were used originally to ship pickled cucumbers from Asia to America. Prices vary but I think more than $20 sounds high. Again, never ever ever use a barrel that previously contained anything toxic or even questionable. There are plenty of used food-material barrels if you look hard enough. When in doubt, assume the worst.
Step 2. Procure the pieces. There are probably tens of different ways to put a faucet into the bottom of a barrel, but I went to Lowe's and got this stuff and it has worked fine. What we have here is a faucet (~$6) that will accept a typical garden hose, some plastic plumbing fitting (~$1) that is threaded inside and will mate with the faucet (faucet outside the barrel, unknown plastic fitting inside the barrel), and a 4 inch x 4 inch piece of thick rubber (~$3) to be used to make gaskets to improve the seal.
Step 3. Make the gasket(s). Trace the diameter of your faucet's threads onto the rubber. Next, drill out the hole for the gasket. Select a drill bit that is close to the size of your faucet's threads. It's better to go smaller than larger due to the fact that you're improving the seal and it's rubber. My faucet came out to be 3/4"and the 3/4" hole is snug on the threads.
Step 4. Drill a hole in the bottom of the barrel to receive the faucet. This should be the same diameter as the hole you drilled in the gasket. Obviously you want to drill as close to the bottom of the barrel as possible, without compromising the bottom of the barrel. Plastic drills easily so hold the drill firmly to get a clean hole. Do not wiggle the bit around as this hole needs to be crisp and tight.
Step 5. Screw on the faucet. Since your hole is exactly the same size as your faucet's threads, it should be a little difficult to get the faucet going. Remember to keep the faucet perpendicular to the wall of the barrel, and that the plastic is going to yield to the metal. Push firmly while you twist, keeping the faucet in the same orientation the entire time so you don't end up widening the hole. Screw the faucet in all the way, stopping when it is in the correct orientation. Don't go further and then back out to straighten; this will result in a drippy faucet.
Step 6. Get in the barrel. Screw on the gasket and the plastic fitting.
Step 7. Install screen to keep out mosquitoes. Mosquitoes breed in standing water and that's what rain barrels do, so screen is essential. Our barrels have threaded rings at the top to retain a lid (sort of like a giant mason jar). We tossed the lid but kept the ring and just laid screen across the top of the barrel before screwing the ring on. Make sure the screen is tight.
Step 8. Elevate! Just as water towers are elevated to increase pressure so that the water will come out of your tap (without energy-intensive pumping), the rain barrels will deliver better if they are elevated to increase pressure. Ours are going to have soaker hoses running down and through the garden beds. We'll be able to turn on the faucet for about 20 minutes and the gardens will be watered to perfection.
We still need to build the awning that will drain into the barrels (increasing the surface area will collect more water), but now we don't have to worry about mosquitoes, and we know they work!
Thanks, Nathan! If you have any questions about rain barrels, soaker hoses, or how to get out of an old pickle jar, feel free to leave them in the comments.