How Many Ounces in Drinking a Gallon of Water a Day?

Sixteen 8-ounce glasses of water equal one gallon.
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Let's get straight to the point: There are 128 ounces in a gallon, so to drink a gallon of water in one day, you'd need to drink 16 eight-ounce glasses. It seems like an impossible task, but a 2008 study from the journal Obesity found that drinking more water every day can help bolster weight-loss efforts. Using a calorie-tracker tool is also a great resource to help shed the pounds.


And according to another 2009 study also from Obesity, people who drink a couple glasses of water before a meal tend to eat up to 75 fewer calories at that particular sitting. Even though this amount might not seem impressive at first, study author Brenda Davy, Ph.D, says that can add up to losing 10 pounds or more in a year.

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So what does drinking a gallon of water in one day look like? Ounce by ounce, it's a lot of liquid to ingest — and a lot of trips to the bathroom — but spread throughout the day, it's an achievable goal.

How Much Water Should You Drink a Day?

How many ounces of water you should drink each day depends on several factors including your body weight, activity level and current health status. While there's no magic number of glasses of water to drink in a day, many health authorities recommend using your thirst as your guide.

If you eat plenty of fruits and vegetables and consume beverages that contain water, you're likely getting 70 percent of your water needs met through your overall diet. While the majority of that amount comes from the beverages you drink, there are some estimates that we get about 22 percent of our water from food. This is good news, especially if you struggle to sip water throughout the day.


But in case you need some hard numbers to help guide your water intake, The National Academies of Sciences, Engineering, and Medicine determined that an adequate daily fluid intake is:

  • About 15.5 cups (3.7 liters) of fluids for men
  • About 11.5 cups (2.7 liters) of fluids a day for women

Additionally, the Institute of Medicine recommends that a healthy adult drink 78 to 100 ounces (about nine to 13 cups) of fluids per day, on average.


Conversion Rate for Ounces to Gallons

Water is often referred to in ounces, especially when talking about how much you need to drink in a day. But what happens when the bottle you're using is in gallons? How do you convert ounces to gallons? First, let's go over how many ounces are in a gallon:


  • 128 fluid ounces = 1 US gallon
  • 160 ounces (UK) = 1 UK gallon


If you're not excited about the idea of lugging around a one-gallon plastic container of water, you might be wondering how many glasses you need to drink to get to one-gallon. A typical glass of water is eight ounces. If you use the same size glass, you will need to drink 16 glasses of water (8 ounces each) to reach one gallon each day.

How to Drink a Gallon of Water a Day

Step 1: Chug Water When You Wake Up

Drink two glasses of water right after you wake up. Make sure each glass holds approximately eight ounces of water. An easy way to accomplish this is by filling a 16-ounce water bottle and placing it beside your bed each night so you always have easy access to water.


Step 2: Sip Water While You Get Ready

Have a glass of water while you're preparing breakfast and getting dressed. Then, during breakfast, drink an additional glass, which will help you digest your meal and ensure that you start the day well-hydrated.

Keep a designated 8-ounce glass of water that you use when at home. Even decorating it can help you remember to keep drinking while making the experience a bit more fun.


Step 3: Have a Glass of Water With Lunch

Enjoy three glasses of water before lunch. If you exercise during this part of the day, drink additional water to replenish the reserves you expel through sweating.

Have two glasses of water with lunch. If your lunch is protein- or fiber-heavy, having this amount of water will also help digestion. Remember to keep a filled water bottle with you at all times, wherever you go, so that you can continue hydrating throughout the day.


Step 4: Enhance the Flavor of Your Water

Consume at least three glasses of fresh water between lunch and dinner. Add a slice of lemon, some fresh mint or cucumber slices to give your drink a refreshing flavor and add variety, but don't add sugar, which reduces the effectiveness of all of the hydrating you're doing.


Remember, your total water intake can also come from other beverages. If you need a sugar-free alternative to water, consider a commercial sparkling water drink such as La Croix.

Step 5: Drink Water With Dinner

Have a glass of water while you're preparing dinner then wash down dinner with another two glasses of water. You should have consumed nearly a gallon of water by this time. It's important to drink the majority of your water before late evening to help reduce bathroom breaks during the night.

Step 6: Finish the Day by Drinking More Water

Instead of dessert or a late-night snack, have a warm glass of water, perhaps with some lemon or grated ginger, which can have a calming effect before getting ready for bed.

It's easy to confuse the feeling of thirst with hunger, causing many people to overeat when they're actually just thirsty. Ending your day with a drink of water will help reduce late-night munching and facilitate digestion throughout the night.

Track How Much Water You’re Drinking

Making the commitment to increase your total water consumption is only half of the equation; you also need to track how much you're actually drinking each day. There are several ways to tally your water each time you reach for a glass.

One method that's easy, convenient, and keeps all of your information in one place is the MyPlate Calorie Tracker from LIVESTRONG. All you have to do is drink your water, input the information into MyPlate and the program does the rest. With handy charts and graphs, you will always know how close you are to your one-gallon goal for the day.

If you're tracking efforts show that you're coming up short on your daily quota, consider trying a few of these tips:

  • Instead of a sip of water with your morning medication or vitamins, drink a full eight-ounce glass.
  • Heavy coffee drinker? Have a full serving of water between mugs.
  • Do the same when you're drinking alcohol, alternating cocktails or beer with a full 16-ounce pub glass of water (which counts as two servings).
  • Drink 20 ounces of water two hours before a workout, drink about 10 ounces every 15 minutes of the workout and another eight ounces as soon as the workout completes.
  • Feel hungry at the 3 pm slump? Have a glass of water because you may just be thirsty.
  • Never leave home without a full reusable water bottle.
  • Order water with your meal at restaurants and save the cocktail for dessert, if you still have room.


The Health Benefits of Drinking Water

Your body needs water to survive. Plain and simple. But beyond the requirement to sustain life, water also has countless benefits that contribute to your overall health including:

Side Effects of Drinking Too Much Water

Even if you're concerned about your weight, don't drink massive amounts of water, which may lead to overhydration. In addition to people trying to lose weight, this can sometimes happen with endurance athletes who drink in excess believing they will prevent dehydration.

Unfortunately, when taken to excess, overhydration can lead to hyponatremia, a condition characterized by low levels of sodium in the blood. Symptoms include irritability, confusion, nausea, headaches and, in severe cases, coma.

Since there's no "one-size-fits-all" recommendation for the amount of water you need to drink in a day, knowing if you are overhydrated can be difficult. A general rule of thumb for endurance athletes is to weigh yourself before and after a long exercise session. This can help determine the amount of water you lost and how much you need to drink to replenish your body.

When it comes to dehydration, heat stroke and overhydration, it's best to let your symptoms be your guide, and consult your doctor right away if you have any concerns.