The idea that everyone must drink exactly eight glasses of water a day is one of the most persistent health myths. While hydration is crucial, the “8×8 rule” (eight 8-ounce glasses) isn’t based on scientific evidence. The truth is, water needs vary from person to person depending on factors like climate, activity level, diet, and overall health. The National Academies of Sciences recommends about 3.7 liters for men and 2.7 liters for women per day—from all fluids and food sources combined.
Your body is excellent at signaling when you need water—through thirst. Clear or pale yellow urine is also a reliable indicator of good hydration. Plus, water-rich foods like fruits, vegetables, and soups contribute significantly to daily intake. Rigidly following the eight-glass rule can lead to overhydration, which in rare cases may cause electrolyte imbalances, especially during endurance sports.
In fact, forcing yourself to drink more water than your body needs isn’t necessarily beneficial. Instead, listen to your body’s cues. Drink when you’re thirsty, increase intake in hot weather or during intense physical activity, and pay attention to signs like dry mouth or fatigue. Hydration is important, but it’s not one-size-fits-all.
