If we are being honest, most of us know we need to drink more water. We may have bought large reusable bottles with good intentions, but our daily fluid intake often consists mainly of tea, a few fizzy drinks, and some alcohol in the evening. However, this habit does not benefit our health. Our bodies are composed of about 50% water, and we lose some of this every day through breathing and sweating, so we must constantly replenish it. Without enough water, we would not survive for more than a few days. Failing to replace lost fluids can lead to dehydration, which, according to Dr Jonathan Webster, can significantly impact our health and well-being. The Doctify GP explains that dehydration can cause several unpleasant side effects, including headaches, confusion, tiredness, constipation, lack of concentration, and urinary tract infections (UTIs). UTIs can be extremely painful, so it is best to avoid them.
General Fluid Recommendations
According to the NHS, most people need between 1.5 and 2 litres of fluid per day. While plain water is the best choice, fluids can also come from foods and drinks that contain water, such as tea, coffee, milk, melon, soups, and stews. However, this is a general guideline, and the exact amount varies by age and gender. Dr Webster has provided a more detailed breakdown based on life stage.
Children (4-8 years): 1.2 litres per day
Young children under eight should aim for about 1.2 litres of fluids daily, equivalent to six to eight 200ml glasses. Dr Webster explains that their bodies are still developing, and hydration is crucial for brain function, digestion, and regulating body temperature. He warns that parents may need to encourage children to drink regularly, as they might not recognize thirst.
Teenagers: 1.6 to 1.9 litres for boys, 1.5 litres for girls per day
Teenagers, especially those aged 14 to 18, need more water than most adults. During this growth period, hydration needs increase, and water is essential for maintaining energy, supporting metabolism, and aiding muscle function. Teen boys require between 1.6 and 1.9 litres per day, while teenage girls need about 1.5 litres. As a rough guide, 1.5 to 2 litres is approximately three to four pint glasses of water.
Adults under 60: 1.6 litres for women, 2 litres for men per day
For adults under 60, the general advice is for men to drink 2 litres of water per day and women to have 1.6 litres. However, Dr Webster notes that factors such as exercise, climate, and diet influence individual needs. Proper hydration helps with temperature regulation, kidney function, and concentration.
Adults over 60: 1.6 to 2 litres per day
People over 60 should aim for 1.6 to 2 litres of fluid daily, regardless of gender. As we age, our thirst sensation decreases, making dehydration more likely. Staying hydrated supports joint health, digestion, and helps prevent UTIs. Dr Webster emphasizes that conscious effort to drink regularly is key.
How to Tell If You Are Dehydrated
The NHS recommends checking the colour of your urine. If you are drinking enough fluids, it should be the colour of white wine. Darker urine indicates you should drink more water.
Factors That Affect Water Requirements
Healthcare professionals note that exact water needs vary based on age, gender, activity level, climate, and overall health. Dr Nadira Awal, a Doctify-rated GP and founder of Pause and Co Healthcare, explains that while these guidelines provide a general framework, the best indicator of proper hydration is listening to your body and checking urine colour. Thirst is a reliable sign that you need more fluids, and pale yellow urine suggests adequate hydration.
Pregnancy and Breastfeeding
Water requirements increase during pregnancy and breastfeeding. Dr Awal recommends about 10 cups (2.3 litres) per day during pregnancy. Lactating women should aim for about 13 cups (3 litres) daily to support milk production and stay hydrated.
Physical Activity Levels
Exercise or strenuous physical work drastically raises fluid needs. It is recommended to drink two cups of water before exercise and one cup every 15 to 20 minutes during activity. Continue drinking after your workout to replenish lost fluids.
Climate and Environment
Living in hot climates or at high elevations can increase fluid loss through sweat and respiration. Dr Awal advises individuals in these conditions to drink water regularly throughout the day, even if they do not feel thirsty.
Health Issues
During fever, vomiting, or diarrhoea, it is critical to increase water intake to replace lost fluids and prevent dehydration. The exact amount depends on the severity of the illness, but aim to keep urine pale and avoid thirst.
This article was first published in May 2025.
