Data quality, concepts and methodology: Basic definitions
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Total water intake refers to the total amount of water added to the water system of the facility to replace water discharged or consumed during production. It maybe broken down into the amounts withdrawn from various sources (for example, surface water, groundwater, etc.) and the amounts used for various purposes, or end uses. The latter refers to the initial use of water in these purposes – cooling, processing, condensing, and steam generation, and sanitary and other purposes. Cooling and condensing water refers to water used for the production of steam or the dissipation of waste heat. Processing water refers to water that comes in contact with an intermediate or final product of the manufacturing or mining operation. Sanitary water use serves basic human sanitary requirements at industrial facilities.
Recirculated water (recirculation or recycling) refers to water used more than once in an industrial facility, and in Canada applies mainly to cooling and processing activities. Recirculation does not refer to water used a number of times within a particular process subsystem of a facility but only to water that leaves a particular process subsystem and re-enters it or is used in another process. Recirculation and water intake combine to form the water input system of a facility.
Gross water use refers to the total amount of water used in the production of the product. It is the sum of total water intake and water recirculation.
Water consumption refers to water that is lost in the production process. In other words, consumed water is not returned to its original source. The two major portions of consumed water are escaped steam and the incorporation of water into a product, as for example in the production of soft drinks. Water consumption is a strictly local concept for the purposes of this report, and refers to water not returned to the source of abstraction in the vicinity of the facility in question. In the broader context, because of the earth’s water cycle, water is never really consumed. For example, evaporated water falls back to the earth in the form of precipitation, and is not lost to the environment as a whole. In this report, consumption is an accounting concept used to describe the water balances at single facilities only. It is the sum of total water intake minus water discharge.
Wastewater discharge refers to water that is returned to the environment in the form of water usually close to the facility. Discharged water may be treated or untreated. Together, water discharge and water consumption form the effluent subsystem of the facility. The sum of these two parameters is approximately equal to the total water intake of the facility.