Why do cells need water?
Almost all living cells require water for normal functioning.
Water is an essential constituent of the protoplasm of living cells because it is directly involved in countless biochemical reactions like photosynthesis and respiration. Without it cells couldn't move waste and by-products, take in nutrients, perform intracelluar transportation, functioning and signalling.
All of these characteristics are due to water's inherent chemical and physical properties i.e. it is a versatile solvent which has a high specific heat capacity.