1.1 The guide provides information and clarity to support the health and maintenance of Marine Sanitation Devices (MSDs) on maritime vessels and platforms to promote effective operations and performance throughout the lifecycle. This includes identification of chemicals and their derivatives that can be detrimental to proper MSD operations. This guide will promote better understanding of the impacts of certain chemicals on the health and operations of MSD systems, plus provide guidance to inform operators of best practices and procedures for effective operations and maintenance. This guide is designed to assist both operators and MSD Original Equipment Manufacturers (OEMs) in collaboratively working to ensure effective operations and maintenance, and to reduce performance degradations that result from the introduction of harmful chemicals. The primary application of this guide is to Type II MSDs (described in Section 4), installed on larger ships and employing biological treatment of sewage and gray water.