Your body knows how much water it needs

If you've ever struggled drinking eight glasses, you can dial it back, new research suggests.

Michelle Starr Science editor
Michelle Starr is CNET's science editor, and she hopes to get you as enthralled with the wonders of the universe as she is. When she's not daydreaming about flying through space, she's daydreaming about bats.
Michelle Starr
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One-size-fits-all approaches to daily intakes just don't work, but water has always seemed to be the exception, with the recommendation that everyone drinks eight glasses a day. If you've struggled to drink this much water in your daily life, you can now relax. New research suggests that everyone's needs vary -- and that your body will tell you when you've had enough.

The study found that swallowing fluid becomes difficult after you've satisfied your need for water, which helps maintain the body's individual water requirements, keeping you hydrated while not poisoning yourself with too much water. When you overhydrate, your electrolytes become unbalanced, which can disrupt brain function and potentially kill you. (This takes around 6 litres or 202 fl oz, give or take, so 8 glasses is still in the safe range.)

"Here for the first time we found effort-full swallowing after drinking excess water which meant they were having to overcome some sort of resistance. This was compatible with our notion that the swallowing reflex becomes inhibited once enough water has been drunk," said study supervisor Michael Farrell in a statement.

"If we just do what our body demands us to we'll probably get it right -- just drink according to thirst rather than an elaborate schedule."