With what the fish are eating these days and now from Japan, I would not worry too much about a little poop.
Ron, In the quote below you said you dumped in a ditch next to the driveway. That is what I was referring to as "illegal" dumping. As far as legally dumping gray water, I do know of some states that the only thing allowed to be dumped on their highways is fresh water. You must remember that the gray water comes out of the same opening that black water does, so unless you spotlessly clean the common drain line you will get some black water remnants exiting. As far as the solution to dump in the concrete opening at a dump station and wash the area down upon completion, I do not know about your dumping, but when you open the dump valve the volume and pressure will shoot the contents all over and will not be contained in that little trough area. Much easier to go to the store and get a hose and then dump. Just my thoughts but anyone else have some ideas. Bob"Without human solid waste, we flush our black and gray tanks only upon returning from our trips. I pour in a half bottle of bleach in the toilet, and a half bottle in the kitchen sink, then fill up the two tanks to capacity with fresh warm water. After an hour or two, I then drain them into the ditch next to the driveway, and repeat the process with fresh warm water alone. The result is clean odor-free tanks."