We all need water, especially in hot weather. Water makes up over 50 per cent of the average adult’s body weight, and up to 70 per cent in babies. Despite years of public education, many of us are still dehydrated, particularly older people. Men need more water than women. So how much is enough?
Thirst is not always a reliable guide. Keeping an eye on your urine is a good idea. It should be very pale yellow. Dark yellow/brown is a sign that you’re seriously dehydrated.
Everyone’s water needs are a bit different, but as a guide, Australian health authorities recommend that men should drink about ten cups (2.6 litres) of fluids each day, and women about eight cups (2.1 litres). Children need about 4-5 cups, and teenagers need 6-8 cups per day.
Each day we lose water via breathing, perspiration, urine and bowel movements. Every cell, tissue and organ in the human body needs water to work properly. Even mild dehydration can drain your energy and make you feel tired.
For older people, not drinking enough water commonly leads to problems such as constipation and confusion. Medicines like diuretics and laxatives can also cause dehydration.
When do you need more water?
- Hot or humid weather means you need to drink more (remembering extreme humidity can’t always be countered by drinking water).
- Your body loses fluid when you have fever, vomiting or diarrhoea. Drinking more water at these times is a great idea, and sometimes extra hydrolytes are also needed, to replace lost minerals.
- Any activity that makes you sweat means you need to drink extra water to cover that fluid loss. Exercise physiologists recommend drinking water before, during and after intense physical activity, even if the weather is cold.
- Being at high altitude dries people out faster.
- Women who are pregnant or breast-feeding often need additional fluids to stay hydrated.
Humans get about 20 per cent of the water we need from food (for example, watermelon, spinach and celery are mostly water). Lots of popular beverages are mostly water, but if sugar, caffeine, alcohol or fat are added, they can cause other problems. Pure water is best.
Can you drink too much water?
This is rarely a problem for healthy adults, but there is a condition called hyponatraemia, in which too much water in the body dilutes the sodium content of blood. Athletes who drink far too much water sometimes have this problem, in which the kidneys can’t get rid of the excess water. Symptoms like nausea, confusion and seizures can be the result.
Hyponatraemia can be life threatening in extreme cases. Getting not enough water is a much more common problem though!
If you don’t like the taste of plain water, adding berries, lemon slices or other fruit can make it more interesting. There’s also sparkling water, and herbal and iced teas.
In some medical cases, water intake needs to be carefully managed.
People with chronic kidney disease, heart failure or liver disease sometimes have trouble efficiently clearing water from the body. Your GP can help advise how much water to aim for each day if you have one of these conditions.
