Vatten

Vatten, or water, is a chemical compound with the formula H2O, consisting of two hydrogen atoms covalently bonded to one oxygen atom. It is a colorless, tasteless, and odorless liquid under standard conditions. Water exhibits cohesion and a high surface tension, a high heat capacity, and a high heat of vaporization. In addition, its solid form, ice, is less dense than liquid water, causing ice to float. This anomalous behavior is due to hydrogen bonding between molecules.

Vatten covers about 71 percent of the Earth's surface, primarily as salt water in oceans. Freshwater is unevenly distributed, with most of it stored in glaciers and groundwater. The majority of freshwater is used for drinking, agriculture, industry, and energy production. The global water cycle moves water through evaporation, condensation, precipitation, infiltration, runoff, and transpiration, linking oceans, atmosphere, soils, and biosphere.

Water quality depends on chemical and biological composition. Safe drinking water must meet health-based standards and is often treated to remove pathogens, adjust pH, and reduce minerals. Common treatment steps include coagulation, filtration, and disinfection; desalination recovers fresh water from seawater or brackish sources. In environmental management, water resources are monitored for pollution, overuse, and ecosystem health. Access to clean water remains a global priority, as water scarcity, drought, and contamination threaten human societies and natural systems.