“Drink eight glasses a day” is one of the most repeated health tips around. It is easy to remember, but your real needs depend on your body, your activity and the weather. Here is a simpler way to think about hydration.
What the experts say
According to Mayo Clinic, studies suggest the average healthy adult gets enough fluid with about 11.5 cups (2.7 liters) to 15.5 cups (3.7 liters) of total fluid a day, from all sources (Mayo Clinic). That range is not all plain water. It includes other drinks and the water in your food.
In fact, roughly one-fifth of your daily water comes from food. Fruits and vegetables such as watermelon, strawberries, cantaloupe, cabbage and squash are almost entirely water.
Signs you are drinking enough
- You rarely feel thirsty.
- Your urine is colorless or light yellow.
Dark urine, headaches and feeling sluggish during exercise can be signs you need more fluid.
When you need more
- Exercise: drink before, during and after a workout, especially if you sweat a lot.
- Hot or humid weather: you lose more fluid through sweat.
- Illness: fever, vomiting or diarrhea increase fluid needs.
- Pregnancy and breastfeeding: needs go up. Ask your doctor what is right for you.
Hydration and fiber go together
If you are adding more fiber to your diet, drink more fluids too. Fiber works best when it absorbs water, and enough fluid helps avoid bloating and discomfort.
Thirsty or hungry?
Thirst and hunger can feel surprisingly similar, especially in the afternoon. If a snack craving hits soon after a meal, try a glass of water first and wait 10 minutes. Sometimes the craving passes. Sometimes it does not, and then you will know you are genuinely hungry.
Easy ways to drink more
- Start the day with a glass of water before coffee.
- Keep a reusable bottle in sight on your desk or in your bag.
- Pair water with habits you already have: one glass with each meal.
- Add flavor naturally: lemon, cucumber, mint or a few berries.
- Eat your water: soups, salads, fruit and vegetables all count.
Can you drink too much?
It is rare for healthy adults, but drinking very large amounts in a short time can be harmful. People with certain kidney, heart or liver conditions may need to limit fluids. If you have a medical condition, ask your doctor how much is right for you.
The bottom line
There is no single number that fits everyone. Drink regularly through the day, eat plenty of water-rich foods, and use thirst and urine color as your guide.
