How much water do you really need each day?
July 22, 2025
You’ve probably heard the advice to drink eight glasses of water every day. But is that really the amount you need to stay healthy and hydrated?
The truth is, it depends. How much water you need varies based on your age, weight, activity level, and even the weather. Especially when the temperatures climb, staying properly hydrated becomes even more important.
“The eight-glasses-a-day rule is a good general reminder, but the truth is drinking water is not a one-size-fits-all approach,” says Kal Caldera, Family Medicine, Saint Agnes Care. “Some people may need to drink more, especially if they’re active or spending time outside in the heat.”
Why hydration matters in the heat
When it’s hot and you’re outside, your body loses water faster through sweat. Without enough fluids, you can become dehydrated and possibly experience fatigue, headaches, dizziness or worse.
Water keeps your body cool, supports your blood pressure, and moves nutrients where they’re needed. Electrolytes, minerals like sodium, potassium and magnesium, are also important as they help balance fluids and keep your muscles and nerves working properly.
Is water the only option?
Water is the best choice for staying hydrated, but it’s not the only option. There are other liquid alternatives you can try to keep things interesting:
- Sparkling water (choose varieties without added sugar)
- Flavored water with natural fruit infusions like lemon or cucumber
- Sports drinks such as Gatorade, especially after heavy sweating; use in moderation
- Coconut water which is naturally rich in potassium
Plus, fruits and vegetables like watermelon, oranges, cucumbers and celery contain a high water content which can also help keep you hydrated.
“The key is really to listen to your body,” says Dr. Caldera. “If you feel thirsty, you’re already mildly dehydrated. Sip water regularly throughout the day, not just when you’re very thirsty.”
How to tell if you're getting enough water
Wondering if you're staying properly hydrated? Here are a few signs to watch for:
- Your urine is light yellow or clear. Dark or strong-smelling urine can be an early sign of dehydration.
- You feel alert and focused. Dehydration can cause brain fog, fatigue or headaches.
- You're going to the bathroom regularly. Most people should be urinating every two to four hours
- You're not feeling overly thirsty. Constantly feeling thirsty may mean that you're body is playing catch up on the fluids it needs
- Your skin and lips feel normal. Dry lips or skin can be an outward clue that your body needs more water.
If you're experiencing frequent headaches, low energy or dizziness, especially in the heat, it could be a sign that you're not drinking enough water.
The bottom line on hydration
Drinking water isn’t just something to think about during workouts or when you’re outside in the summer heat. Staying hydrated is a basic part of good health, especially in hot weather. Water supports everything from brain function to blood pressure to digestion.
One easy way to stay hydrated is to keep a water bottle nearby, choose hydrating snacks like fruit, and pay attention to how your body feels. If you have questions about hydration or other wellness habits, a primary care provider can help you make a plan that fits your lifestyle.
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