I had planned to add rain barrels to some of our downspouts this spring, but I think it's going to at least wait a couple more years. In doing the research, I've run into too many concerns that mushroomed the project into more than I can handle right now.
The biggest concern is how exactly I could use the water I collected this way. Due to the presence of bird crap on roofs, most resources were pretty clear that rain barrel water isn't potable. I didn't look into what filtering would be required to make it ok for humans to drink but presumably it's more than just boiling it. But lots of resources felt it would be best to use the water on plants I didn't intend to eat since I have an asphalt shingle roof and who knows what those petrochemicals washing out of the asphalt would to do to the people who eat those plants. This wouldn't be a big deal if I grew mostly flowers. But I have veggies, fruit trees, herbs and berries. The flowers I have are mixed in with the food. I couldn't find out if I wasn't supposed to put the rain barrel water directly on the plant (sprinkler, watering can, etc) or if I wasn't supposed to put that water on the soil for the roots to access. Is it a matter of stuff one could wash off the plant after harvest? Or is it a matter of toxics being absorbed into the plant where I can't wash it off?
Several pages suggested letting the first ten minutes of rain wash off the roof and then redirecting the water into the rain barrels. Um, yeah. It rains a lot here - at night.
Add to this the downspout rerouting I'd need to do: downspout to barrel (as a direct feed or as a Y with a switch) and then the overflow back to the original downspout destination. Several of the barrels I looked at have a hose-sized overflow, which seems inadequate for something that can receive upwards of 100 gallons of rain water per storm - water destined for a barrel that holds between 40 and 75 gallons, at a time when I won't be watering since it's raining. So I either need to retrofit a barrel with a downspout sized overflow or get one of the few barrels that come that way to prevent barrel flooding. I need to come up with a system for removing the rain barrels from the downspout and hooking everything back up the way it is now (a reason for those Y dividers) for winter; full barrels suffer when it freezes as the water inside expands - although I'm not sure an empty barrel would do better since we lost a plastic cover to the front porch light to the freezing weather this winter (no, really, the plastic just crumbled in our hands).
Top it all off: I have a really small yard and a homeowner's association with guidelines and rules about what I can do to the outside of my property. Since we're in an end unit, my rainbarrels and their accouterments must at the very least be neat and tidy; they might possibly need to be downright invisible.
So, realizing that I was becoming overwhelmed trying to wrap my head around all this, I decided that it's going to have to wait. Perhaps this is even a place where I might need to admit I can't do everything myself.