Hydration22 July 2026 · 4 min read
Hydration is not really about eight glasses
The number everyone repeats has almost no evidence behind it. What matters more is timing, temperature and what you are drinking alongside.
The eight-glasses rule has been repeated so often that it now feels like settled science. It is not. It appears to trace back to a 1945 recommendation that also noted most of the requirement is met through food — a sentence that fell off somewhere along the way.
A better way to judge it
Thirst is a reasonable guide for most healthy adults. Urine colour is a better one: pale straw is where you want to be. Dark yellow means catch up; completely clear usually means you have overdone it.
Where people actually go wrong
- Drinking most of the day's water after sunset, then sleeping badly for it.
- Counting sweetened drinks toward the total while ignoring what else they bring.
- Increasing dietary fibre without increasing fluid — a reliable route to discomfort.
- Assuming tea and coffee do not count. In moderate amounts, they do.
If you are in a Pakistani summer, working outdoors, exercising, pregnant or nursing, your requirement is meaningfully higher. Judge by output, not by a number you read once.
This article is provided for general informational purposes and does not constitute medical advice, diagnosis or treatment. Speak to your physician or a qualified practitioner about your own circumstances before making changes, particularly if you are pregnant, nursing, taking medication or managing a medical condition.
Written by
DN Urooj Hussain
Clinical Dietitian & Founder · Doctor of Nutrition (DN)
A clinical dietitian who built the product she kept wishing she could hand her patients.
More writing like this, twice a month
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