Great video of harvesting rainwater in an off grid environment. By catching the rain on a 300 square foot metal roof and having it go into a 2000 gallon plastic tank this fellow has been providing water to his home and for his family for 20 years. It seems a very simple set up. The water lands on the roofing and goes through pvc pipe into the take. Before entering the tank there is a filter and in the bottom of the filter he places a chlorine puck (like for a pool) which shocks the water so it is clean before it enters the tank. He also add some bleach once in a while.
Since the water is shocked this way before entering the tank he never has to climb inside and scrub it down like some people do. He lives in Canada and gets enough rainfall in winter to fill the tank so they have plenty of water all year. He ran the pipe to get water from the hill top to the house and they put it under ground to both protect it and to insulate it from freezing. His filter looks like a clear two liter bottle and you can see through it which is the brand he prefers since you can see when it needs to be cleaned.
To keep the filter from freezing he has a small hole drilled into the bottom of it and when the temperatures are above freezing he put a small twig into the hole to keep the water from dripping a lot but when the temps are freezing he takes the twig out so the water is always dripping (moving) and doesn’t freeze.
This is a pretty smart set up but very simple. If you are off grid and not restricted from harvesting rainwater, this might be an idea that you can use. Even a small one similar to this would be great to water farm animals. you could put metal roofing on the chicken coop or a shed.