Doctors often advise extra fluids during respiratory infections like colds, flu, or bronchitis to replace losses from fever and to help thin mucus.
Hot or humid weather increases perspiration, while high altitudes and dry indoor heat can accelerate moisture loss through the skin. Extra Fluids
Fluid needs increase to approximately 2.3 liters (10 cups) daily during pregnancy and 3.1 liters (13 cups) while breastfeeding to support the body's increased demands. Managing Fluid Intake Extra Fluids
Not all "extra fluids" have to be plain water. You can reach hydration goals through various sources: Diarrhoea Treatment Guidelines Extra Fluids
Intense exercise causes fluid loss through sweat; drinking before, during, and after activity is essential for recovery.