In fact a similar thing happened in my family but my parents have darkening hair, and my siblings have minimally darkening blonde and brown hair. There is even some red mixed in somewhere.
A lot of desalinization plants just release the salty brine back out to sea, it's actually an ecological problem, so finding another use for it might convince them to capture and separate that for manufacturing uses.
Considering this one makes several of the other ones listed here more viable, I think it would have the most impact.