Posts Tagged ‘daily fluid intake’

Am I drinking enough?

April 18, 2010

Question:  Am I drinking enough?

Answer:   Have 2 litres of fluid daily.  Drink 8 glasses of water every 24 hours. Drink when you’re thirsty…

We hear many answers to this common question.  But is there one correct answer?

Based on the explanations of different health authorities and health organisations we can calculate how much fluid to drink daily as follows:


– Replacement approach. The average urine output for adults is about 1.5 litres daily. We lose about another litre of water daily through breathing, sweating and bowel movements.  So if we consume 2 litres of water or other beverages a day, along with a normal diet which automatically contributes some water through different foods, we will typically replace our lost fluids.

– Eight 8-ounce glasses of water a day. Another approach to fluid intake is the “8 x 8 rule” — drink eight 8-ounce (approx. 250 ml) glasses of fluid a day. Many people use this rule of thumb as a guideline for how much water and other fluids to drink daily.

– Dietary recommendations. The US Institute of Medicine advises that men consume about 3 litres of total beverages a day and women consume about 2.2 litres of total beverages a day.

Another way of approaching this is by drinking enough fluid so that you rarely feel thirsty. But this is not a reliable method, as one may start feeling thirsty when dehydration has already set in.

Also, it is said that if you produce colourless or slightly yellow urine, your fluid intake is probably adequate.  But again, this is a very general indication.

All the above applies to healthy adults in normal conditions. People who are involved in intensive exercise and sports training, or in working environments where a lot of perspiration is produced, as well as people suffering from illness or chronic health conditions, or females who are pregnant or breastfeeding have different requirements.

Anybody who is concerned about their fluid intake should check with their doctor or a registered dietitian. 

Though water is recommended as one of the best sources of fluid, 100% pure fruit juices and low-fat milk are also healthy options, both being sources of  water and of different nutrients.  

Remember that many fruits and vegetables are also high in water content: for example, watermelon and tomatoes are 90% or more water by weight.

The British Nutrition Foundation has just produced this handy sheet about a healthy daily fluid intake. It also refers to caffeinated drinks and soft-drinks and the need to curtail their intake.

BNF Healthy Hydration guide