What are the functions and types of water?

Water (H₂O) covers ~71% of Earth's surface and makes up 60–70% of the human body.

Functions of water:

In the human body:

• Solvent dissolves nutrients, minerals, and gases for transport through the bloodstream
• Temperature regulation sweating releases heat; water's high specific heat capacity stabilizes body temperature
• Metabolic medium biochemical reactions require an aqueous environment
• Lubrication cushions joints, protects the spinal cord, lubricates eyes and digestive tract
• Transport carries oxygen, hormones, and nutrients to cells; removes waste products

In nature:

• Hydrological cycle evaporation, condensation, and precipitation distribute fresh water globally
• Habitat oceans, rivers, lakes support the majority of Earth's biodiversity
• Climate regulation oceans absorb and store solar heat, moderating global temperature
• Weathering and erosion shapes geological features over millions of years

Types of water:

By source:

• Surface water (rivers, lakes, reservoirs)
• Groundwater (underground aquifers)
• Rainwater (directly from precipitation)
• Seawater (oceans — ~97% of all water; saline)
• Glacial water (ice caps/glaciers — ~2% of all water; fresh but frozen)

By treatment:

• Potable water — safe to drink
• Distilled water — all impurities removed; used in labs
• Mineral water — naturally contains dissolved minerals
• Hard water — high calcium and magnesium content
• Soft water — low mineral content

By physical state: Liquid (0–100°C), Ice (below 0°C), Water vapor/steam (above 100°C at standard pressure)