Using it to flush the commode might not be a health issue when you've flushed, but you may end up with some smelly stuff growing in the tank between flushes, and your toilet bowl would probably have a ring around it and maybe some growth, too. Depends on what you're washing and what your detergent is.

It's one of those things that sounds like a good idea, but I'd rather you test it out first. :->

The law I referred to is about collecting rainwater, which the state expects to be used for all its water needs: drinking, irrigation, etc. Re-using greywater is probably not covered under that statute. Health and plumbing codes would be the governing laws for that re-use. I don't think the state is expecting greywater in its aquifers and streams. It may be prohibited.