communicable diseases affecting Navy and Marine Corps personnel. WATER SUPPLY A hygienically safe and continuously dependable water supply is a necessity of life. Drinking water should be free of disease-producing organisms, poisonous chemicals, as well as from objectionable color, odor, and taste. For more detailed instruction on these topics, you should review the Manual of Naval Preventive Medicine, NAVMED P-5010. Water Supply Ashore With rare exceptions, Navy and Marine Corps activities ashore within the continental limits of the United States are situated where a municipal water supply is available. BUMEDINST 6240.1, Standards for Potable Water, sets drinking water standards for U.S. naval establishments worldwide, both ashore and afloat. Water Supply in the Field Hospital Corpsmen are frequently called upon to approve field water sources and to recommend disinfection methods before water is considered safe to drink. Consider water acquired in the field as unsafe until it has been disinfected and tested. Approval of water sources should be based on a thorough surveillance of available water sources. WATER QUANTITY REQUIREMENTS.— The daily water requirements for personnel in the field vary with a number of factors, including the season of the year, geographical location, and the tactical situation. Personnel who do not drink enough water can quickly become dehydrated both in extremely hot or extremely cold climates. WATER TREATMENT.—Water treatment is the process of purifying water to make it potable (safe to drink). Various processes can be used to purify water. These processes include aeration, coagulation, flocculation, filtration, reverse osmosis, and disinfection, all of which are discussed in depth in NAVMED P-5010. Water Supply Afloat Potable water for shipboard use comes from one of several sources: the ship’s distillation plant, shore-to-ship delivery, or ship-to-ship transfer. The ship’s medical department is responsible for determining the quality of the water. The ships engineering section determines the quantity stored or produced, and performs the actual chlorination or bromination. Water Testing Naval vessels follow water testing requirements and procedures outlined in the latest edition of Standard Methods for the Examination of Water and Wastewater, published by the American Public Health Association (APHA), American Water Works Association (AWWA), and the Water Pollution Control Federation (WPCF). Manufacture and Handling of Ice Most ships and shore activities use ice machines to make ice. To reduce bacterial growth, ice used around food or in food or drink must be made from potable water. All ice must be prepared in a sanitary manner and afforded the same protection as potable water. The medical departments aboard ships are required to include ice samples in any bacteriological analyses they perform on water. WASTEWATER TREATMENT AND DISPOSAL Wastewater is the spent water of a ship, base, industrial plant, or other activity. This spent water contains wastes, such as soil, detergent, and sewage. The proper disposal of these waste materials is one of the most important measures for controlling water-borne diseases, such as cholera and typhoid fever. Wastewater Treatment and Disposal Systems Ashore The use of approved municipal or regional wastewater collection and disposal systems is the preferred method for disposing of wastes from shore activities. Accordingly, municipal or regional wastewater disposal systems are used by Navy shore activities whenever feasible. Wastewater Treatment and Disposal Systems Afloat The overboard discharge of untreated sewage from DoD ships within the navigable waters of the United 10-5