We've been doing this for many years. I hate using my drinking water (we are on a well) for flowers. I catch rainwater in large drums and pump it to a 200 gallon tank sitting 10 feet in the air. From there, it is all gravity fed. A 2 inch line out of the tank to a 3/4 inch line to a 5/8 inch line. A couple shutoffs inbetween for any maintenance I need to do. I have about 250 feet of hose to water all the flower beds. Plenty of pressure. If I had to do it over again, I would like to get the tank higher - about 15 feet and have about a 300 gallon tank for added line pressure. Of course my tower would have to be sturdier to handle the excess weight, that is why I have not rebuilt it yet. About a tenth inch rain off my barn roof yields about 60 gallon of water, so about 3 good rains in the spring fills the tank. Only a couple dry summers have I had to pull water from the pond to supplement the rainfall. Good luck, it is a lot of fun to do. Also, I put "Aquashade" or similiar pond dyes in the stored water when pumping to the storage tank to reduce algae growth. There are many similiar products out there. A gallon will last you many years. Everything is drained in the winter to avoid problems.
)? I can't quite make out the smaller pipes on the bottom, I see how they collect from all 3 tanks. how do they empty? Thanks. Mark