I drank one gallon of water a day for a month — here’s what happened to my body

a photo of a woman holding a water bottle
(Image credit: Shutterstock)

You’ve probably heard about the importance of staying hydrated, and drinking enough water has been hailed as the solution to many health issues — from losing weight to clearing skin breakouts. But how much water should you be drinking per day, and what happens to your body when you up your water intake?

To find out more, and separate fact from fiction, I filled my best water bottle multiple times and drank a gallon of water every single day for a month. 

From speeding up your metabolism to brightening your skin and reducing headaches, drinking a gallon of water is supposed to have a number of health benefits. As I sipped on my water, I kept a close eye on what all that H2O did for my skin, my hunger levels, my energy, and my workouts. Read on to find out what happened. 

How much water should you drink per day? 

When it comes to how much water you should drink each day, the jury is out. Both the Centers for Disease Control and Prevention (CDC) and the Food and Nutrition Board (FNB) say you should drink to thirst. That said, the FNB says as a goal, women should aim for around 2.7 liters per day, and men should drink about 3.7 liters of water. A gallon of water is 3.7 liters. 

Of course, it goes without saying that you should listen to your body. If you're super-active, or you're pregnant, you'll definitely want to focus on your water intake to avoid dehydration. Always check with your doctor if you're unsure about how much water you should be drinking, or if you think you have signs of dehydration.

According to research, approximately 75% of Americans are chronically dehydrated, which can cause fatigue, weakness, and loss of stamina.

How much is a gallon of water? 

As mentioned above, a gallon of water is 3.785 liters of water. I already drink a lot throughout the day, but for this challenge, I ensured that this water count was only water, not coffee or herbal teas. 

I drank a gallon of water a day for a month — here’s what happened 

It turns out that guzzling more water wasn’t the magical cure-all I was hoping for. Here’s what I learned a month later. 

1. I needed to pee, a lot

This one isn’t that surprising, or pretty, but turns out that drinking a gallon of water means you take a lot more trips to the bathroom. It’s pretty simple really — the more liquid you drink, the more that comes out. That said, science says this isn’t a bad thing — the more you pee, the more toxins you’re flushing out of your body. It can also help your body break down its food more easily, and studies have found drinking enough water can relieve constipation. 

At the beginning of my month, I noticed that the toilet trips didn’t stop when I did and that I was getting up in the night to go for a pee. As someone who prioritizes eight hours of sleep per night, this wasn’t fun, so I started having my last drink of water a couple of hours before my bedtime to ensure I didn’t need that midnight pee. 

2. I felt less hungry

While the first few days of upping my water intake left me a little bloated, once that subsided, I definitely noticed that I snacked less throughout the day. And there’s a simple reason for this — drinking water, especially before mealtimes, can help you feel more full, and therefore eat less. 

While I’m not trying to lose weight, studies have found that increasing your water intake can aid weight loss as it increases your metabolism, and prevent you from feeling as hungry. Of course, long-term weight loss comes from eating a healthy diet, exercising, and sleeping well, so sipping water alone isn’t enough, but if weight loss is a goal, adding more water to your day cannot hurt. 

3. I didn’t notice any improvements in my skin

I was hoping, after a month of drinking a gallon of water a day, I’d be able to say I had the glowing skin of a foundation commercial, but alas, I still have breakouts. Most of my spots occur around my jawline, which is often caused by fluctuations in hormones, however, and no amount of water is going to help that. 

The skin is made up of three different layers, and if the outermost layer of the skin, the epidermis, doesn’t contain enough water, your skin can lose elasticity. Yet after doing some digging, there doesn’t seem to be any research that proves that drinking more water has much impact on the skin’s hydration. Instead, it seems to be what you put on your skin that makes a difference. 

4. I still had hormonal headaches

According to research, dehydration is a common cause of headaches and migraines, so I thought drinking a gallon of water a day would help get rid of mine. While I didn’t get as many headaches as normal towards the end of my working day (something I always put down to staring at my laptop for too long), I did still get headaches first thing, although according to my period tracking app, these might be hormonal. 

5. I had to time my water consumption with my workouts

Water can help transport oxygen and glucose around your body, which in turn, can give you more energy during your workouts. Dehydration can also negatively affect your workout performance — dehydration occurs when you lose as little as 2% of your body’s water content, however when you’re sweating, you can easily lose more than this when working out. 

As a general rule, I always drink to thirst during my workouts and when I’m running. While I didn’t notice any dramatic difference in my athletic performance, I did find that I had to time my last drink at least 30 minutes before heading out the door, as otherwise I’d feel sluggish, and develop a side stitch. I also imagine that because I was drinking a gallon of water a day, I wasn’t dehydrated at all during the past month, meaning I wasn’t suffering any signs of dehydration during my long runs and strength sessions. 

6. I did notice my energy levels increase

As the month went on, and I learned to time my water consumption to avoid night-time visits to the toilet, I noticed I felt more energetic in the day. I spent less time staring into space at work, and I wonder whether it was the water. 

According to the experts, having a regular supply of water helps to increase the electrical functioning in your brain, helping you to think clearer. 

During the month, I also cut down my caffeine intake, as I was naturally sipping on water more than tea and coffee. Although this took some adjusting to, by the end of the month, I felt much better. 

I drank a gallon of water a day for a month — My verdict 

Other benefits of drinking a gallon of water include reduced hangovers, less puffy under-eye bags, and better energy levels. I only had a couple of glasses of wine over the past month, so remained hungover-free, and I didn’t notice much difference in the puffiness around my eyes. That said, I did feel more energetic and I was able to concentrate better at work.

I also learned to love the taste of water. Before this month, I’d often opt for a drop of squash in my water bottle, but that felt like cheating for this challenge. After sipping gallons of the stuff, I found the easiest way to enjoy the water was to chuck a couple of ice cubes into my insulated bottle, meaning the water stayed cool for a few hours. I’d also mix things up by adding a slice of cucumber here and there. (Check out our picks for the best water bottles.)

My verdict? After a month, the habit of having my water bottle by my side is well and truly established. While I won’t be keeping as close an eye on my consumption levels going forward, I will continue to sip water throughout the day. If you’re suffering daily headaches, and energy slumps, and find you’re permanently grazing, this might be a challenge to try — just don’t expect miracles when it comes to your skin.

It goes without saying, certain medical conditions may require a restricted water intake to avoid fluid overload. If you are undergoing treatment, it’s worth checking with your doctor before altering your fluid intake. 

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Jane McGuire
Fitness editor

Jane McGuire is Tom's Guide's Fitness editor, which means she looks after everything fitness related - from running gear to yoga mats. An avid runner, Jane has tested and reviewed fitness products for the past five years, so knows what to look for when finding a good running watch or a pair of shorts with pockets big enough for your smartphone. When she's not pounding the pavements, you'll find Jane striding round the Surrey Hills, taking far too many photos of her puppy.