Not explain to me how that works for a state like Arizona, where the closest salt water body is ~80km to the state boundary, yet the closest metro area (Tucson or phoenix) is 250+km. How does processing and delivery get paid for? Note those are the two closest areas.
I picked AZ because there are neighborhoods growing and some are having to rely on trucked in water.
I agree that foreign aid is a good way to avoid conflict. I'd love to see the US help the entire world have access to clean water. Shame that they dismantled the apparatus for providing it.
Federal budget is federal budget.
Different funds are appropriated for different purposes, funding the kind of research you're talking about would likely be connected to an NSF grant or a national lab. Note as well that science, like everything else, experiences diminishing returns. Putting 1000x the money into water treatment research won't get you 1000x the return. Allocating funds at the scale of the federal government isn't zero sum; you can saturate the amount of funding it's possible to provide, and it does make sense to spread funding around many different areas.
Incidentally, that research you want to see is probably in jeopardy because the grant funding it contains forbidden words like "environment."
Unless of course you happen to be one of the people actively and directly causing the problem they're studying. Then it might seem like a smart idea to put those people out of work.