The uniform thickness of the tanks makes them much more durable than the traditional rotational molded and thermoformed varieties. Blow-molded HDPE tanks are an integral component to all recreational vehicles. Tanks are built to standards specified by IAPMO (International Association of Plumbing and Mechanical Officials) and the Canadian Standards Association. 27.7 Width x 53.5 Length x 7.5 (9.5" with port) Height Holding Tank 45 Gallon Fresh Water Tank