I want to set up a rain barrel to collect water to use in my garden. Any ideas on how I can do this using only or mostly upcycled materials (cheaply)?
I went through this a few years ago and wrote it up on my website. Prices and links are all Australian, but the idea stands.
The big discovery for me was that there are people who are in the business of finding waterproof drums and reselling them. If you can find one of those in your area they will offer a range of shapes and sizes, and possibly trade-off a little bit of extra expense for a lot of time. Or maybe they'll be cheaper, you won't know until you try. The one I found was cheaper than any other source. But mostly they had about 20 different sizes and shapes of barrels, and had some hard-to-sell ones they were willing to give me even cheaper.
From talking to people I found that the open-top barrels were somewhat painful to deal with as they had a big top opening for relatively little storage capacity. The sealed barrels with a tap fitting at the bottom worked better, and it's easy to cut whatever size hole you want in the top.
A lot depends on what tools you have or are willing to buy. I had a battery drill, so buying a cheap holesaw meant I could make holes to fit the pipe I bought. That made linking everything up very easy.
If you don't want to buy new material, linking to the guttering is going to be tricky. I spent a lot of time and effort (not documented above) trying to get a header tank above our toilet window to fill from the gutter. I gave up, it was easier just to fill the tanks on the ground and pump or bucket water around.
I suggest buying decent taps for the tanks, filling buckets from the top of the tank is hard work (I do it because I'm impatient, everyone else in the house waits for the tap to fill the bucket. But taps have to go at the bottom of the tank, so if they leak your tank empties. Buy some flexible silicon sealant and decent taps.
I've found an abundance of ~50 gal. food grade barrels which I use for rain barrels on Craigslist and other local papers etc. I certainly consider this up-cycled and by the time you spend making another type of container water tight, the small cost far outweighs this in my experience. Further, these containers come with a threaded, 2-piece screw type lid. Basically the same as a mason jar works. you can then either modify the center 'lid' to accommodate your downspout, or you can do what I do and just lay over a piece of screen, and then screw down the 'ring' over it. This keeps debris and mosquito out. The plastic is generally HDPE and easily accommodates a tap with some simple drilling. This is the only way to go in my opinion.
There is this method by NJ Agricultural Experiment Station, which is using not entirely upcycled materials, but somewhat cheaper alternatives to industrial parts. You can find the link to the video below...
A lot of municipalities will also offer subsidized or free rain barrels to residents; it helps lessen the load on the local storm water collection infrastructure during heavy rains. Check with your local city hall.