- Duncombe, Iowa offers several convenient options for RV dumping.- Pattee City Park provides a dumping station for black water and gray water, as well as fresh water and a hose for flushing tanks.- Another option is the Ames Water Pollution Control Facility, which offers dumping facilities for both black and gray water.- Travelers can also visit the Des Moines West KOA Campground, which features a dump station along with other amenities like gas stations and restaurants.- Walnut Woods State Park is another nearby option that offers an RV trash bin and waste disposal facilities.