Drinking plenty of water every day is essential for good health. Australian tap water is the best choice for staying well hydrated.

Why is water important for good health?

Water is an essential part of a healthy balanced diet because the body relies on it to function properly. Between 50% and 80% of the human body is made up of water. All the body’s chemical processes take place in water. We need water for digestion, to absorb nutrients, to help us move, get rid of waste products and to regulate our body temperature.

If the body doesn’t have enough water (known as dehydration), it won’t function as well. People who don’t drink enough water every day are at greater risk of kidney stones, problems with their heart valves and some kinds of cancer. Even minor dehydration can affect physical and mental performance.

Drinking water is also essential for the health of your mouth. Drinking water in most parts of Australia contains fluoride, which helps to protect against tooth decay. Water is also needed for the body to make saliva, which is important for washing food away from the teeth and helping you chew, taste, swallow and digest food.

How much water should I drink?

The amount of water that someone should drink varies greatly from person to person. It depends on how your individual metabolism works, what the temperature is, what you eat, your age and whether you have a medical condition. It’s especially important for children and older people to drink enough water.

We get about one fifth of the water we need from food and the rest from drinking fluids. The body gets rid of water throughout the day through breathing and sweating, as well as by going to the toilet.

As a general rule, men need about 10 cups of fluids every day and women need about 8 cups (add another cup a day if you are pregnant or breastfeeding). Babies need 0.7 to 0.8 litres of fluid a day from breast milk or formula, while children need between 4 cups (for 1-year-olds) and 6 to 8 cups a day (for teenagers). In Australia, 1 cup is equivalent to 250ml.

You can get water from any fluids — including tea and coffee, fruit juice and soft drinks. But be careful how much of these you drink since they can make you put on weight, damage your teeth and have an unwanted stimulant effect.

Australian tap water is always the best choice.

Is bottled water healthier than tap water?

Bottled water has no more health benefits than tap water. Tap water is just as safe to drink, unless there has been an incident in the area that affects the quality of the water, such as a flood or the discovery of bacteria in the supply. The fluoride in tap water is also important for healthy teeth.

Many people believe bottled water is healthier because it contains added minerals. However, studies have shown that bottled water can have less magnesium, potassium and calcium than tap water. Some varieties can also contain higher levels of potentially harmful substances, including chlorine, nitrate and chemicals released from the plastic such as bisphenol A (BPA).

Bottled water has lower quality controls than tap drinking water, while plastic bottles are not good for the environment.

How can I stay hydrated?

To stay hydrated, it’s important to drink before you feel thirsty. This is especially important if you are exercising or if it’s a hot day. Even if you’re not thirsty, try to drink water regularly throughout the day.

You can tell if you are well hydrated by the colour of your urine. If it is pale yellow or straw-coloured, you are probably hydrated. If it’s darker, you need to drink more water.

You can see the colour your urine should be on this urine colour chart — but remember that taking some medicines or vitamin supplements can change the colour of your urine for a few hours.

You can stay hydrated by:

• always carrying a water bottle with you
• keeping chilled water in the fridge on hot days
• flavouring water with lemon, strawberries or mint to add flavour
• always having water on the table when you’re eating

What happens when you don’t drink enough water?

Not drinking enough water can make you very ill. Severe dehydration can lead to dizziness and collapse. If you are showing any signs of dehydration, drink some water straight away and seek medical advice if you still don't feel better.

Older people are at greater risk of dehydration because they naturally feel less thirsty and their kidneys may not work as well. Memory problems, taking some medicines such as diuretics and laxatives and not being able to move around to fetch a drink all make it harder to stay hydrated.

For older people, not drinking enough water in the long term can lead to serious problems such as constipation, a decline in memory, not being able to function as well, having a fall, and having a stroke.

These are the signs that you need to drink more water:

• dark urine
• light headedness
• tiredness
• irritability
• feeling thirsty
• loss of appetite
• fainting

Is it possible to drink too much water?

In some people, drinking too much water can lead to a dangerous condition called hyponatremia, where the levels of sodium in the blood become too diluted. This can occasionally happen to people who drink too much while they’re doing intense physical activity, such as running a marathon. Babies can also have too much water if their formula is too diluted.

People with chronic kidney disease, heart failure or liver disease, who cannot get rid of water from the body as efficiently, should talk to their doctor about how much water to drink. If you have some other long-term medical condition, it is also a good idea to discuss your water consumption habits with the doctor.