If you look up “rain barrel” on the internet you will find a thousand different directions to make them. Although a simple task, all those different directions make it seem daunting. Really, the only daunting thing is to find food grade recycled barrels. You can put together the rest of the barrel from what you find in your local hardware store.
My best tip is to make sure your hole tool and your PVC and other fittings are the same size as the hole bit you choose.

To build your barrel you need a FOOD grade container of some sort. Search your area for barrel recycling locations – there are many companies who sell recycled barrels. Get a fair sized barrel, pictured here are 50 and 60 gallons.
Next you will need a drill, something with some power behind it to cut the plastic. Hole saw or paddle drill bits need to be SLIGHTLY larger in size than the spigot and overflow male valves you choose. Get both the same size and only buy one bit.
Jigsaw to cut the top off of the barrel
Units to make a PVC overflow: male threaded on one side - this is a male adaptor , one female threaded on one side but the interior of the fitting needs to be smooth - this is a bushing and female and male need to fit together with no more than 1/4" gap, one rubber washer.
Units to make a spigot: spigot or silcock of choice: 1 rubber washer, 1 metal washer, one male or female threaded adapter that can screw into your spigot (there will be a gap). The two washers seal and fill the gap. ImageImageImage
Cement blocks or a riser you make to go under the barrel. You need at least two blocks
Screen and trash elastics, OR 2 hinges depends on the style of barrel you choose
Flexible downspout, 2 machine screws
Hosing that corresponds to the size of your overflow or “jump” valve.
Make sure you work in an area that can be messy. There will probably be left over liquids in the barrel, and cutting the plastic makes a mess. You also need ventilation incase the tool heats the plastic. I work outside at home.
First thing I do is cut the top off of the barrel like Sandra is doing here.Image
Cut all the way around the barrel, on the INSIDE top lip. If you have a screw lid barrel, you need to cut the inside of the screw top to out leaving the threaded band around the edge intact. Next, Sandra likes to use a rasp to soften those sharp edges. Now you can crawl in the barrel to put o the spigot! We won't show Sandra in the barrel. It isn't very lady like!
ImageNow you are going to begin drilling your holes for the spigot and your overflow or jump valves. A jump is a small hose that links barrels together in succession to fill one after the other from a single downspout. It's an excellent idea if you have a particularly active downspout.
Remember your choice of drill bit for this depends on the size of fittings you chose. You need the hole to be SLIGHTLY larger than your spigot. If in doubt I suggest going to a hardware store that offers personal service. You can use a whole saw drill bit which is like a round tube with teeth (works best) or a paddle bit.
I like to drill one hole about two to three inches below the top rim. This is the overflow or the jump hole. I use a male and female threaded on one end PVC fittings and a washer (rubber or metal, rubber is best) and fit that into the hole very tightly. I put my overflow off to one side or the other, the photo below shows it above the spigot. It's your choice.Image
Next, you drill your spigot hole where you'd like it. I prefer my hole 5 to 6 inches from the bottom of the barrel. This means I can use only one set of cement blocks to reach watering can height. I don't suggest making it any higher in the barrel as you can't reach water below this point (which is why I dip!!). Shown here is the interior of the spigot fixture all put together. The rubber and metal washer create a great seal, and the male copper adapter is the right size for the job. Find your fittings as you need them. Tighten with a wrench.
Finishing up is now a snap! You are almost done!!
Now you need to cut the screen for the top. Cut it larger, and use two huge rubber bands (found to hold trash bags in place, these are removable) or screw it down with your screw lid.
Now you need to go outside and fit your barrel into it's new home! Take your two cement blocks and set them out from the house about 10".Image
Level them, and set the barrel on top. Now you can add your overflow, or if you have two barrels in succession (or more) you can put your jumps in place and fool with the blocks to get it right. All that is left to
do is to measure where you need the flex downspout to attach to your aluminum downspout. Cut your aluminum downspout and afix the plastic flex spout to it with the two tiny machine screws. DONE! All you need to do is wait for rain!!
A handy tip: if you try to get creative like I did in some photos and make lids that don't fit quite right (there was a lot of experimenting to perfect the method to the right), just pop in a bit of biological mosquito control powder to keep the "wrigglers" out of your barrel!