Drinking Water: How Much You Need

Water is the least glamorous thing in your kitchen and the most important. It costs almost nothing from the tap, and your body can't do without it. The internet loves to overcomplicate it, so here's what Australian health authorities actually say.

Why your body needs water

Water makes up 50–80% of your body weight, depending on how much lean muscle you carry ¹. You use it to digest food and absorb nutrients, carry things round your body, get rid of waste, and keep your temperature steady ¹². Saliva is mostly water, so it matters for your teeth and mouth too ².

You lose water all day: through breathing, sweating and going to the toilet ². In a 70 kg adult, the normal daily turnover is about 2.5 to 3 litres ¹. Lose as little as 2% of your body weight in water and your body and mind start to work less well ¹.

How much should you drink?

There is no strict number. Healthdirect, the Australian Government's health information service, says the amount depends on what you eat, your age, the weather, your health, your metabolism and how active you are ².

As a general guide for fluids from drinks ²:

| Who | Fluids a day | |---|---| | Men | About 10 cups (2.6 litres) | | Women | About 8 cups (2.1 litres) | | Pregnant or breastfeeding | Add about 1 more cup | | Teenagers | 6 to 8 cups | | Children | 4 to 5 cups |

An Australian cup is about 250 mL ².

These come from Australia's Nutrient Reference Values ¹. They're a sensible average, not a daily test.

Food counts too

About one fifth of the water you take in comes from food ². Soups, stews, fruit and vegetables all help. Cucumber, watermelon, oranges and lettuce are mostly water. A bowl of winter vegetable soup or a big Greek salad adds to your total.

Does tea and coffee count?

Yes. All drinks add fluid: milk, juice, soup, tea and coffee ². Tea and coffee contain caffeine, which can make you pass a bit more urine ², but they still count. Healthdirect suggests going easy on juice, cordial and soft drinks, because they add sugar that can affect your weight and teeth ². Water is the best everyday choice.

Is Australian tap water safe?

In most of Australia, yes. Healthdirect calls tap water the best choice for staying hydrated ².

The rules behind it are the Australian Drinking Water Guidelines, written by the National Health and Medical Research Council ³. They give water regulators and suppliers a framework for monitoring and managing water quality ³. The guidelines aren't law on their own; each state and territory puts them into practice through its health department and water regulator ³. They're updated on a rolling basis as new evidence comes in ³. Experts updated the limits for PFAS, the so-called "forever chemicals", in June 2025 ².

Health authorities test tap water for chemicals, bacteria and parasites such as Giardia, Cryptosporidium and E. coli ². Occasionally, after a flood or a contamination scare, they may tell people in an area to boil water or use bottled water ². If that happens, follow your local water authority's advice.

Fluoride. In most parts of Australia, tap water contains fluoride, which helps protect against tooth decay ². Bottled water usually doesn't.

Tanks and bores. Rainwater tanks and private bores aren't covered by your water utility's testing. There are separate safety guidelines for them, so check with your state health department if you rely on one ².

When you need more

Drink more on hot days and when you exercise, and don't wait for thirst ². The easiest check is the colour of your wee: pale yellow or straw-coloured means you're probably well hydrated; darker yellow means drink more ².

Signs you need water include thirst, headaches, a dry mouth, tiredness, irritability and feeling light-headed ². Older people are at greater risk because they naturally feel less thirsty, and dehydration in babies and children is serious and needs medical attention straight away ². During an Australian summer, heat can also lead to heat exhaustion and heat stroke ¹.

Easy ways to drink more

Keep a jug of water in the fridge. Cold water gets drunk.
Add flavour without sugar: a slice of lemon or lime, cucumber, a few mint or basil leaves, or a slice of ginger.
Brew a big pot of tea, herbal or otherwise, and chill it.
Put a glass of water on the table at every meal.
Carry a refillable bottle. It saves money and plastic.

A note on "water cures"

You may have read that drinking extra water will melt fat, flush out toxins or cure whatever ails you. We're not going to tell you that. Water does essential jobs in your body, and staying hydrated helps you feel and perform your best. If something is wrong, see a doctor. A glass of water is good for you; it isn't medicine.

For more drinks ideas, see our drinks and smoothies collections.

Sources

National Health and Medical Research Council and New Zealand Ministry of Health, "Water", Nutrient Reference Values for Australia and New Zealand, Eat For Health. https://www.eatforhealth.gov.au/nutrient-reference-values/nutrients/water
Healthdirect Australia, "Drinking water and your health". https://www.healthdirect.gov.au/drinking-water-and-your-health
National Health and Medical Research Council, "Australian Drinking Water Guidelines" (2011, updated). https://www.nhmrc.gov.au/about-us/publications/australian-drinking-water-guidelines