There is a RV dump station at Mayport Naval Station. They have potable water and non-potable rinse water available. To get there, take exit I-295 and head east onto FL-10 Atlantic Blvd. Continue east for 7 miles until you reach A1A. Turn left onto A1A (heading north) and follow the signs to the Naval Station. Enter through the main gate on Mayport Road, which will become Main Street. Take a right onto Massey Avenue and then a left onto Bon Homme Richard Street.