Will salt water harm the Purple® Seat Cushion? Great question! Our Purple® Seat Cushions will not be harmed by fresh or salt water. Related articles Can I cut the Purple™ Seat Cushion to fit a specific seat size? How do I clean the Purple® Seat Cushion? Can I leave the Purple material in a hot car? What Purple® Seat cushion is recommend for coccyx pain? Can the Purple® Seat Cushions be used in the shower?