Our biggest concern used to be that every community had a different set of regulations, with many regulations set by people that had no knowledge of anything to do with waste water. That changed when we worked with local government agencies that were trying to set a common standard. They learned a lot and were able to set those common standards for the entire Puget Sound region. Suggest your local agencies contact the Dump Smart program in Washington State, as the work has already been done.
We buy pump outs just because ground dumping can look bad to the ignorant. Unless you're using products with high solvent content, extreme pH, or pumped with oxidizers, there's nothing in your waste water that will hurt a lawn. (In a drought situation shrubbery may be more sensitive to the pH of your waste.) The Dump Smart regulations allow ground dumping no closer than 100 feet from surface water.
I've had actual lab testing done on our waste water, which became the basis for educating our local authorities and enabling the reasonable regional regulations. Dumping into storm drains or letting your runoff go into surface water is bad for a couple of reasons: Suspended fine particulate kills fish that aren't accustomed to high silt water; Our systems force a lot of air into the water, which will also kill marine life. Oxidizers will kill marine life. As mentioned before, a lot of alkalines spur plant growth, which can cause excess algae growth in waterways.
Proper ground dumping is fine if you pay attention to where, pumping to a sanitary drain is preferable. Never dump in the street.
