As usual, this is a noncommercial post. I provide extensive sourcing here, but no corporate entity has provided any financial consideration in exchange for being cited.
(1) THE BIG BARRIER TO RAIN HARVESTING.
When researching stock tank gardens a year ago, my challenge was that there was almost no relevant information on the internet - I had to invent a system.
With rain harvesting, I had the opposite problem - an overloadof information, an avalanche of greenie propaganda, and umpteen million commercial rain harvesting vendors, applications, and configurations that simply were not relevant to my specific goal, which was a volume-effective but easily-managed system at a rock-bottom price that an ordinary urban or suburban homeowner could DIY in a weekend or two without the need for specialized skills or tools. So once again, I've been forced to think through a new type of application here, but in response to a very different challenge.