I can fully understand pre-treating before disposal. The problem lies with the fact that you can't even get a permit to dump in a sanitary sewer.
It's no wonder that there are only a handful of pressure washing companies in a town of over 500,000.
I'm kind of in the same boat as you. I have called around to so many different people and can never get a straight answer.
I have an email that was sent to me that outlines the specific areas and ways that you can discharge wastewater in Colorado.
According to the Colorado Water Quality...