Disposing of winter anti-freeze ??

If you are talking about RV antifreeze that's in your water lines, than it's safe to just dump it in the sewer line. Typically, you hook up fresh water and run fresh water through all the water lines until everything is clear, so the water will be in your gray and black water tanks. Then, just dump your tanks as you normally would. And, don't forget to sanitize your fresh water tank before your first trip.

RV antifreeze isn't toxic, so it is safe to handle as waste water.