You should drink plenty of fluids to avoid becoming dehydrated.
Most of the time, you can prevent dehydration by drinking water regularly throughout the day. Be guided by your thirst, but be aware that in hot weather, when exercising and during illness, you should drink more.
Mild dehydration can be relieved by drinking more water and diluted fruit squash. If necessary, you can purchase oral rehydration solutions (ORS) from a pharmacy. As a guide, passing pale or clear-coloured urine (wee) is a good sign that you're well hydrated.
If you're active, or if the weather is particularly hot, there's a greater risk that you will become dehydrated. To prevent becoming dehydrated, you should increase your fluid intake.
As different people sweat at different rates, it's very difficult to provide specific recommendations about how much fluid you should drink. However, you should drink more than normal while exercising, and it's particularly important to keep well hydrated if you're exercising in warm conditions. This is because you will sweat more and fluid will be lost from your body more rapidly.
Rarely, drinking more fluid than your body can process can reduce the amount of sodium (salt) in your blood. This can lead to a serious and potentially fatal condition called hyponatremia. If you start to feel discomfort and bloating from drinking, stop drinking and allow time to recover.
If you, your child or someone you are caring for is ill, particularly with a fever, vomiting or diarrhoea, there's a high risk of becoming dehydrated, so it's important to start replacing fluid as soon as possible.
Advice for children
There are no specific recommendations regarding the amount of water or other fluids that children need.
However, it's important for children to replace lost fluid, to prevent dehydration. Like adults, children lose more water when they are in hotter climates and when they are physically active.
You should give your child healthy drinks as part of an overall healthy, balanced diet.
See the page on drinks and cups for more information and advice on specific drinks for young children.