Medical experts said that drinking eight glasses of water a day may be insufficient for people living through extreme heatwaves [1, 2].
This guidance is critical as rising temperatures increase the risk of dehydration. Because the body loses more fluids through sweat in hot climates, adhering to a rigid universal water goal can lead to health complications.
In regions experiencing high temperatures, such as Pakistan, hydration needs vary significantly based on individual health and environmental conditions [5, 1]. While the common rule of eight glasses is often cited as a baseline, that amount is roughly two liters [3]. Some medical perspectives said this amount is a myth and unnecessary even in hot weather [3], while other experts said that heatwaves necessitate a higher intake to compensate for fluid loss [1, 4].
Doctors said that the requirement for water is not static. Factors such as activity level, humidity, and overall health influence how much a person should drink [1, 2]. Relying on a fixed number rather than listening to the body's signals, such as thirst or urine color, can result in inadequate hydration during peak summer months [4].
To determine a precise hydration number, some professionals recommend using science-based online tools rather than following general rules of thumb [4]. These tools can account for specific variables that a standard eight-glass recommendation ignores. This approach allows individuals to adjust their intake based on the severity of the heat and their specific physical requirements [1, 4].
“Eight glasses of water a day may be insufficient during extreme heat.”
The shift from a universal 'eight-glass' rule to personalized hydration reflects a broader medical understanding that biological needs are not one-size-fits-all. As global temperatures rise and heatwaves become more frequent, public health guidance is moving toward dynamic intake strategies that prioritize individual physiological responses over static numerical targets.
