Advice about drinking water ranges from eight glasses a day to carrying a large bottle everywhere. Staying hydrated is important, but the amount you need is more flexible than most people think, and many drinks and foods count towards it.
Why Water Is Important
Water makes up around half of a woman's body weight. It helps control your body temperature and carries nutrients to your cells. Your kidneys also need it to remove waste. Even mild dehydration can cause headaches and make it harder to concentrate. It can also make constipation worse.
How Much Do You Need?
Most women need around 2 litres of water a day in total. About a fifth of this usually comes from food, especially fruit, vegetables, soups and yoghurt. That leaves roughly 1.5 to 2 litres to come from drinks, or six to eight glasses.
You need more when:
The weather is hot
You exercise, especially for longer than an hour or in the heat
You are pregnant, which adds around 300 millilitres a day
You are breastfeeding, which adds around 700 millilitres a day
You have a fever
What Counts?
Water is the best choice, but other drinks count too. Milk, plant drinks, herbal tea, tea and coffee all contribute. Coffee and tea have a mild effect that makes you pass more urine, but in normal amounts they still add to your fluid overall. Sugary and fizzy drinks also hydrate you, but they add sugar without much benefit, so they are best kept for occasional use.
Alcohol is different. It makes you lose more fluid than it provides, so drinking water alongside it is a good idea.
The Eight Glasses Myth
The idea that everyone must drink eight glasses of water a day is often traced back to a 1945 recommendation of about 2.5 litres a day. That same advice also noted that most of this water is contained in food, a detail that was lost over time. There is no evidence that everyone needs exactly eight glasses on top of what they get from food.
How to Tell If You Are Drinking Enough
Your body has two useful guides. Thirst is the first, although it becomes less reliable as you get older. The second is the colour of your urine. Pale yellow means you are well hydrated. Dark yellow suggests you need to drink more, while completely clear urine all day may mean you are drinking more than you need.
Can You Drink Too Much?
Yes, although it is rare. Drinking very large amounts quickly, most often during long endurance events such as marathons, can dilute the salt in your blood to a dangerous level. During long exercise, drink to thirst rather than forcing fluids.
Do You Need Electrolyte Drinks?
Electrolytes are minerals such as sodium and potassium, which help your body hold on to fluid. They can help during long exercise in the heat, or when you have been ill with vomiting or diarrhoea. For everyday life and short workouts, water and regular meals provide all you need.
For most women, a simple habit is enough. Keep a glass or bottle within reach and drink with each meal, adding more when it is hot or you are active.