Consumption of water from a reservoir or water supply system. A distinction is made between the use of return water, where the collected water is returned to the watercourse, and the use of non-return water, where it is used for evaporation and filtration.

The consumption of water supplied to meet the various needs of the population, industry, etc. There are two main categories of water use 1) domestic, drinking and communal - water consumption related to the domestic needs of the population (drinking, cooking, keeping homes clean, etc.) and ensuring the improvement of populated areas (irrigation of streets, green areas, etc.); 2) industrial or technical - water consumption for technological purposes of industry, energy, transport (evaporation, cooling, washing of products, hydraulic transport, etc.), for fire-fighting needs, etc. The amount of water consumed for the needs of the population depends mainly on the degree of sanitary and technical equipment of the dwellings (availability of sewerage, baths, showers, gas supply systems and hot water supply). An indicator of the level of water consumption in this category is the specific water consumption, i.e. the average amount of water consumed per inhabitant per day. Measurements and analysis of actual unit costs in populated areas provide the basis for the establishment of water consumption standards - the unit cost values recommended for the design of new or the reconstruction of existing water supply systems.