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Do you need to drink 8 glasses of water a day?

UNPROVEN
0 relevant in PubMed PubMed results Last checked April 2026
No human studies were found to support or refute the 8 glasses of water per day recommendation.
The provided studies examined fluid balance in horses on different protein diets and clinical fluid trials in dehydrated children, neither of which addresses daily water requirements for healthy adults. No evidence was found regarding the specific recommendation of 8 glasses of water daily for general health maintenance.
Overall confidence
15%
RCT quality
20%
Expert consensus
10%
RCTs found
0 relevant in PubMed
Largest trial
100 (pediatric emergency study)
Date range
2006–2017
Effect size
none
Key studies
Equine Vet J Suppl · 2006
Study examined protein diet effects on fluid balance in horses, not human daily water needs
PubMed 17402499 ↗
Pediatr Emerg Care · 2017
Study assessed fluid trial adequacy in dehydrated children, not daily water requirements
PubMed 26181504 ↗
Caveats
The search results contained no studies directly examining optimal daily water intake for healthy adults, making evaluation of the 8-glass recommendation impossible from this evidence.

People also ask

What counts as adequate fluid intake?
The pediatric study found clinicians considered >9 mL/kg/hour adequate during illness recovery
Do dietary factors affect water needs?
The horse study suggests high protein intake increases water requirements and fluid losses
Is this recommendation evidence-based?
No relevant human studies were found to evaluate the 8 glasses per day recommendation
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BustMyMyth synthesizes published RCT evidence. It is not medical advice. Always consult a qualified healthcare professional. Sources: PubMed/MEDLINE, Cochrane Library, ClinicalTrials.gov.