[aerohead]

It's something President Trump talked about. 'It's not for individuals'. The rich won't do it. Neither will corporations until there's regulation.
Which leaves government.
Someone dumps raw sewage into the river. People downstream, who rely on the river water complain of human feces floating down from upstream.
Cities have no authority to act unilaterally. Counties may not have any jurisdiction. If states don't want to police it, it ends up in the US Supreme Court, and a new federal administration is born.
Federal standards supersede local standards. No more problem.
We now have ISO standards which have been adopted, worldwide, for much of the developed countries. Building/ Electrical/ Plumbing/ Roads & Highways/ Water treatment.
Some problems are so big, only governments are 'large' enough to do anything about them.