This manual, "Water Supply in Theaters of Operations (FM 10-52)," is a guide for commanders, staff officers, and other persons concerned with planning, organizing, and operating an Army water supply system in a TO. Concepts and doctrine are presented to enable the planner to design a water purification, storage, and distribution system that will ensure units can provide necessary water support to US forces. The doctrine in this manual is oriented toward operations in a tactical theater and in field training exercises. Water supply at fixed and semifixed installations and in peacetime garrison operations is a Corps of Engineers responsibility and is discussed in depth in the TM 5-813 "Water Supply" series manuals and FM 5-104. Doctrine for the development of operation of a theater water supply system is discussed separately or arid and nonarid regions in both developed and undeveloped theaters. Doctrine for the employment and operation of water point equipment will be in FM 10-52-1. Planning factors for water supply in arctic, arid, temperate, and tropical climates are presented for use by logistics planners. Responsibilities for the command, control, and operation of water units in the theater are discuss in detail. Potable water quality standards and surveillance practices are presented. Procedures for management and accountability of water supplies are discussed. The systems described are applicable in LIC, conventional warfare, and operations in an NBC environment on the integrated AirLand battlefield.