I am much happier this year with my rainwater catchment system. Several years ago, we put in 2 giant rainwater tanks, ordered online, with a combined capacity of 850 gallons. We put them at either end of the backyard, attached them to our downspouts with flexible guttering, and hooked on some faucets. Noticed very quickly that they would fill up after only one or two decent rains.
It has taken awhile to get good use out of them. The first year, one tank was too low to really get any rain out of it - it had no pressure. The other one we hooked a hose up to and used it to water fruit trees (very handy since we don't have a faucet on that side of the house).
The next year, we boosted up the second tank with a sturdy base (very sturdy - 500 gallons of water weighs 4160 pounds) and attached a drip system. Tried to attach two timers to the drip system, neither worked and so resorted to setting the microwave timer inside. Completely emptied the tank several times by forgetting to turn it off. During the winter, one of the plastic faucets busted because it froze and there was still some water inside.
This year, I have decided just to use the garden bed tank to fill up my watering can, and the other tank for watering fruit trees and grapes. THAT works great! I kind of enjoy walking around the 3 garden beds with my can. That way I can check on every plant. Of course, if I had a larger garden it would be more of a PITA.
Still, I am very pleased to have fresh rainwater at my command and also as an emergency backup measure. It is a pain to have to clean out the tanks every year, though. But, I am not taking water out of the aquifer, and it's nice to have a system available in case city supplies get cut off for whatever reason.