We come from water, we are water, we need water.
The Eatwell Guide says we should drink six to eight glasses of fluid a day. Water, lower fat milk and sugar-free drinks including tea and coffee all count.
The amount of water you need depends on your size, level of activity, and the heat of your environment.
The table below comes from the European Food Safety Authority. Roughly this shows children need over a litre of fluids a day, and adults need over 2 litres. Note that around a third of your fluid intake comes from food, so the amount of fluid you need from drinks only is lower.
How much fluids should we be drinking
If you are extreme dry, hot or cold environments then you will need more water, as you will be losing more moisture through breathing and sweating. If you are exercising regularly then you will also be losing more moisture and need to replace it. Air conditioned offices and vehicles circulate dry air and can dehydrate you more quickly.
In hot countries people are more aware that they should be drinking 3 litres of fluids a day. If you are exercising lots this is the amount of fluids you should be aiming for.
Remember to stay hydrated, this will result in a better day, everyday!