In the UK it is recommended that we drink around 6-8 glasses (1.2-2 litres) of fluid per day to stay adequately hydrated, but this can vary depending on:
- Level of physical activity
- Environmental temperature and humidity
- The type of food eaten
- Illness or recovery from illness
- Certain health conditions or medications
- Pregnancy or breastfeeding
Being physically active or living in a hot environment can mean that you may need to increase your water intake, the best way to gauge this is by looking at the colour of your urine, if it’s dark in colour then you need to drink more.
Another indicator is thirst, this kicks in when the body is already a little dehydrated, but in the case of older adults whose thirst response is not as effective and young children who may not recognise it, will need support to drink regularly.
There is no UK recommendation for the fluid intake of children, but based on guidance from the EU, younger children need ~120-150ml per drink and older children need around 250ml-300ml. It’s important that children drink an adequate amount as they have a higher proportion of body water than adults, combined with a lower tolerance for heat this can mean that they are more likely to suffer from dehydration.
Pregnant women need to ensure they are staying hydrated as water is needed to produce the amniotic fluid surrounding the baby and to help increase blood volume. Babies that are breastfed will receive all the fluid they need from breastmilk, formula-fed babies may need some extra during hot weather.
Any non-alcoholic beverage can contribute to fluid intake, but the best option is water, it contains no added sugars and is free! Other good options include milk, tea and coffee or low-sugar soft drinks. Caffeine can act as a diuretic in some people so be aware of this but in general most of this effect will be offset by the fluid content of the coffee or tea.
Some examples of food with a high water content include soups or stews, strawberries, watermelon, lettuce, cabbage, celery, spinach and broccoli.
It is worth noting that the water source in your area can have an impact on health, hard water has high concentrations of calcium and magnesium which can benefit cardiovascular health, alternatively soft water which contains high levels of sodium or potassium can aggravate hypertension and heart disease. Soft water can also more easily dissolve certain contaminant minerals such as those found in old pipes, this can be harmful because they can displace essential nutrients, in this situation it is worth running the tap briefly before drinking from the tap.
References
British Nutrition Foundation (2023) Hydration Information – British Nutrition Foundation
Whitney et al (2014) Understanding Nutrition 2nd Edition
MLT Nutrition 