Hydration myths
Most hydration advice is simpler than it sounds. All drinks count towards your fluids, the eight glasses rule is a rule of thumb, and more is not always better.
Updated 21 October 2026. Sources named on the page.
- Five myths and what the guidance says
- Where the eight glasses idea comes from
- A simple, sensible approach
- General information, not medical advice
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Find a figure that suits you
See the national reference amount for your sex in litres and glasses, then adjust for your day.
The reference amounts
These are adequate intakes of fluids from drinks for healthy adults aged 19 and over.
Per day
| Group | Litres | Glasses of 250 mL |
|---|---|---|
| Men | 2.6 L | 10.4 |
| Women | 2.1 L | 8.4 |
Sources: National Health and Medical Research Council (NHMRC), Nutrient Reference Values for Australia and New Zealand, water
Figures and sources checked 21 October 2026. General information, not medical advice.
Myth 1: you must drink exactly eight glasses
Eight glasses is a convenient rule of thumb. The national reference is about 8 glasses of 250 mL for women and about 10 for men, and that counts all drinks. It is a general adult figure, not a rule for every person on every day.
Myth 2: only plain water counts
Tea, coffee, milk and other drinks count towards your fluids, and food adds water on top. Water is a good everyday choice, particularly because it has no sugar or kilojoules, but it is not the only source.
Myth 3: coffee and tea dehydrate you
In usual amounts they count towards your fluids. If caffeine affects your sleep or how you feel, that is a separate reason to cut down.
Myth 4: clear urine means you are doing well
Colour changes with food, vitamins and medicines, so it is only a rough clue. Do not chase a colour. If you are worried about how often you pass urine or how it looks, ask a doctor.
Myth 5: more is always better
Drinking a very large amount in a short time can be harmful. Steady drinking through the day, to thirst, suits most healthy adults.
A simple approach
Have a drink with each meal and one between. Drink more in the heat or when you exercise. Pay attention to thirst. If you have a kidney or heart condition, or are pregnant or breastfeeding, follow the advice of your doctor.
Questions
Where did the eight glasses a day idea come from?
It is a long-standing rule of thumb that is close to the reference for women, once all drinks are counted. It is not a precise requirement.
Is thirst a good guide?
For most healthy adults it works well. Older adults and people who are ill may need to drink by habit as well, so ask a doctor if unsure.
Does sparkling water count?
Yes, it counts towards fluids.
Should I drink extra when I exercise?
Usually yes. Needs rise with heat and exercise.
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