As a herbalist, my patients often tell me “I know I should drink more water.” But, do we really know how much we should drink per day? From the studies on this subject, I would say that it depends on many factors. No study directly answers the question of how much water to drink, but we can get some guidelines. Read on to find out what the studies say is the least requirement. As well as at least one good reason that you might want to increase your intake.

In healthy adults, certain conditions within the body are tightly controlled. These conditions include:

• body temperature
• blood sugar level
• the body’s water content

We take in water as fluids and within foods. We lose it from the lungs when we breathe, in urine and through sweating. Often with wide day-to-day variations in intake and losses. Yet, we have an amazing ability to regulate the amount of water in the body.

So, any calculation of need must account for several influencing factors. Such as:

• climate or environment – hotter climates increase the demand for water
• amount of physical activity – more strenuous activity increases how much we need
• diet – some foods contain a large amount of water, which can reduce the amount of fluid needed

This study suggests an average, sedentary adult should drink at least 1500mls water per day. However, strenuous physical exercise and hotter climates could easily double this need.

However, there may be further reasons to increase your daily water intake. In this study, researchers asked healthy young women to record their food and drink for five days. The women carried out their usual daily activities while taking part. They also filled in a questionnaire about their mood and level of thirst.

Results were sorted into low, moderate and high levels of water intake. Low intake was around 1500ml total intake per day. Whilst high was around double that at about 3000ml total intake per day.

The questionnaires revealed that there was no difference in thirst between the groups. Yet results showed that higher total water intake was associated with better mood. In fact, the women that had the lowest intake were twice as moody as those with the higher intake.

Did drinking more water improve the participants’ mood? Or did happier ladies tend to drink more water? Researchers could not say. Yet, previous studies show that low fluid intake corresponds with more fatigue and tension.

So, since we do know that people with a more positive outlook on life generally appear to have better health and longevity – drink more water and be happy!