These waste/water tanks feature a nominal wall thickness of 0.300". All tanks are molded of FDA approved linear polyethylene. Resin meets FDA spec CTF177 1520 requirements. Satisfies all U.S. coast guard standards. Provides standard NPT openings for vent 1/2", fill 1 1/2" and drain 1/2". Polyethylene tanks will not filter taste into water or emit waste odors.