How much water should you drink per day? It depends

  • 5 Minutes Read
Joanna Kriehn
Joanna Kriehn, MS, RDN, CDCES - Registered Dietitian Nutritionist and Certified Diabetes Care and Education Specialist (CDCES)

Eight glasses of water–is that really how much you should drink per day? Read on to learn about the factors impacting water needs, how much, how often, and how to know if you’re on target.

Water per day

How much water you should drink per day involves several factors

The "eight glasses of water a day" or "drink half your body weight in water" ideas may or may not be best suited for you. Several factors contribute to determining how much fluid you should consume, such as:

Role of water in the body

Although we can survive for weeks without food, we cannot survive for more than a few days without water. Body water allows us to regulate our core temperature to avoid getting too hot or too cold. Body water is also critical for many body processes, including:

How much water should you drink per day?

Review these 2 methods of estimating daily water needs and use what works best for you.

Method 1: Daily adequate intake of water for adults from the National Academies of Sciences

Age Daily Adequate Intake
Men 19 + 3.7L/day or about 13 cups
Women 19 + 2.7L/day or about 9 cups
Pregnant women 3.0 L/day or about 10 cups
Breastfeeding women 3.8 L/day or about 13 cups

This estimation of daily water needs is based on adequate intake (AI) for total daily water, which includes drinking water, beverages, and food, and is based on median total water intakes. These amounts are not a daily target but a general guide.

Method 2: The Academy of Nutrition and Dietetics

The calculation method figures your daily fluid needs based on your calorie intake. You'll want to get in one milliliter (ml) of water for every one calorie you consume. For example, perhaps your weight maintenance calorie target is 2,200 calories/day. Then, your water intake (from both food and liquid sources) should be approximately 2,200 ml/day (just over two quarts).

Remember:

Your fluid goal is higher if you exercise for a long duration in a hot environment. And, of course, if you are thirsty, listen to your body! Don't stop drinking water just because you met your hydration target for the day.

What counts towards your daily water requirement?

All non-alcoholic beverages count towards your daily water requirement, including coffee, tea, juice, and milk. Limit sugar-sweetened beverages to help manage your weight and maintain healthy overall dietary patterns.

Why is it important to track your water intake?

Tracking your water intake per day helps you see where you stand compared to your goals. If you are curious about where you stand regarding hydration, consider tracking your consumption.

When you know (through tracking) that you're getting enough water, you realize what experts already know–water helps you feel energized, helps your skin appear more youthful, and can help you feel full without adding extra calories.

Keeping track using the MyNetDiary app

The MyNetDiary app makes it easy to track hydration. The Water Tracker feature is available on iPhone, Android, and web apps. You can access it directly from your dashboard. Just look for the water glass icon.

Unless you specify otherwise, the app's default glass size is eight fluid ounces (237 ml). For example, if you drink a cup of tea, tap one glass icon.

Also, the Water Tracker feature allows you to customize how much you should drink each day and displays a graph to easily monitor how you're doing (see below).

Note: When you sync MyNetDiary with the iOS Health app, the total volume of water comes from the sum of all filled water glass icons.

Check out the various options under "Water Settings."

If you tend to forget to drink water, MyNetDiary covers that, too! Simply enable Water Reminders under "Settings" in the Water dashboard. Plus, you can schedule the frequency and time range of reminders for further customization (see below).

Are you drinking enough? Common signs of dehydration

If you are dehydrated, then start drinking! You might find it easier to tolerate drinking smaller volumes of water every 15 minutes or so rather than trying to guzzle a massive volume of water all at once. Then, see what you can learn from this experience to recalculate how much you should drink to prevent dehydration from happening again.

Will I lose more weight if I drink more water?

If you replace a caloric beverage with water, then you will consume fewer calories. This could help you lose weight gradually, even if you change nothing else in your diet. Suppose you stop drinking one 20-ounce (591 ml) bottle of root beer and replace it with 20 fluid ounces (591 ml) of water. Savings = 250 calories per day = 1750 calories per week = 7500 calories per month = two pounds per month!

Even if you simply add water to your daily intake, you might benefit from enhanced weight loss if drinking water prevents you from overeating.

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Adapted from original content from Katherine Isacks, MPS, RDN, CDCES

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Tracking & MyNetDiary->Tracking Tips
Apr 16, 2025
Disclaimer: The information provided here does not constitute medical advice. If you are seeking medical advice, please visit your healthcare provider or medical professional.

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