NHS: Water, drinks and hydration — UK guidance on daily fluid intake, fluids from food and drink, recognising dehydration, urine colour indicators, maintaining fluid balance, and when to seek medical advice.
NHS Inform: Hydration — Public health guidance on fluid intake, recognising dehydration, maintaining fluid balance, and understanding risk groups.
Harvard T.H. Chan School of Public Health: Water — Overview of hydration physiology, fluid balance, electrolyte roles, daily fluid requirements, fluid sources, and the contribution of diet to hydration in both general and active populations.
British Dietetic Association: Fluid, water and drinks — Dietetic guidance on fluid intake, hydration, electrolyte balance, physical activity, health conditions, safe intake, and sources of fluid from food and drink.
Johns Hopkins Medicine: Sports and hydration for athletes — Clinical overview of hydration and electrolyte needs during exercise, including strategies before, during and after activity, heat exposure considerations, and monitoring fluid losses.