I think that it might be unaffordable. He hasn’t built one for his own use, so until that happens I’d be out of luck.
What we do have is the 4000 gallon swimming pool, with guttering dumping into it. He had to rig it, because he forgot to tell the guy installing the gutter to put a diverter in and an extender. DUH
Anyway, he put a spigot on the side near the base, and has several hoses that are long enough to reach all his gardens(almost all of our stuff is downhill).
One of those extenders also has a side hook up in just the right place to hook up a hose that I can use to water half of my beds. I’m thinking that I need to place a rain barrel with a spigot right at the end of that, and fill it as needed. Attach another hose to the rain barrel and let it roll.
Then eventually put in a drip irrigation system to eliminate hand watering, and that I might be able to get him to do.