Water—refreshing, life-giving water—has been making waves these days (and I’m not talking about those bad boys in the ocean). There was the giant Stanley tumbler trend and TikTok’s sexy water craze. There’s the fact that everyone has sparkling water in their fridge and electrolyte mixes in their pantry. And now, hydration tech has entered in the chat.

I get it. It’s easier to drink water when it’s loaded with flavor and within arms reach at all times. I thought I was doing a decent enough job, drinking the plain stuff at the recommended 64 ounces per day.

When I was sidelined with a (big, painful) kidney stone, I started to question where that recommendation came from and the overall discourse around hydration. The main advice my urologist gave me was to drink more water. Like, a lot more water. She recommended closer to 4 liters, more than double what I thought I needed.

How could I have gotten my own hydration so wrong?

Hydration, according to science

The 8 x 8 rule (drinking eight, eight-ounce glasses of water), isn’t really rooted in any scientific evidence, but it’s well-circulated advice. Some sources say we need more: The U.S. National Academies of Sciences, Engineering, and Medicine recommend 3.7 total liters of water for adult men (13 cups coming from beverages) and 2.7 liters for adult women (9 cups coming from beverages).

But some sources say we need less: Many news outlets reported on research published in Science in 2022 that pointed to the idea that healthy adults need less than 64 ounces, implying that those of us with access to clean drinking water have been overhydrating. But what the study really highlighted was how variable water turnover is depending on a number of factors:

• Body size
• Sex
• Climate
• Physical activity
• Socioeconomic status (pertaining to access to food and clean water and the type of work you do)
• Whether or not a person was pregnant or breastfeeding

“There is so much contradictory advice because there isn’t really a recommendation,” says Melanie Betz, MS, RD, a Chicago-based registered dietitian who specializes in kidney stones.

For example, those recommendations don’t take into consideration if you’re prone to kidney stones, like me. (Because if you’ve had one kidney stone, you have a 35 to 50 percent chance of having another within five years.)

“For a normal, healthy person with no medical history, I think that the generic eight cups of water per day is a really good starting point,” says Betz.

Some of the confusion may also come from what we’re measuring, such as the amount of water you need to stave off true dehydration versus the amount of water you need to feel your best.

“We certainly know [dehydration],” says Betz. “You know, your blood sodium levels are going to go up and you get dizzy, those types of things. That’s defined … But there’s not a definition of how hydrated you should be to really feel good.”

So, if there are no true guidelines to hydration, how can you determine what you need?

Smart hydration tech to hydrate smarter

Enter hydration trackers in their many forms. If the amount of water you need depends on changing factors such as physical activity or climate, it makes sense that you may need some assistance in calculating what your body needs. This is especially true for older adults or people who are less likely to feel thirsty.

My doctor’s recommendation of 4 liters of water didn’t factor in that I’m also a long distance runner and that I still intended to train for several races in the summer’s heat and humidity. How was I going to adjust my hydration plan further?

Enter: new hydration wearables to very specifically adjust my needs.

The two products I tested are similar in scope, measuring your sweat and electrolyte loss throughout a session. The first product, Nix, is a sensor you attach to your arm via a recyclable patch. The patch ensures your sweat is sealed off and doesn’t evaporate, in theory giving you a more precise reading.

The other product, hDrop is a more traditional sports band—a one and done purchase—but it’s possible to see how more sweat is likely to evaporate.

Both Nix and hDrop were easy to set up, requiring a quick download of their respective apps that connect to the devices via Bluetooth and quick creation of an account. The hDrop app even includes a tutorial on setup and how to interpret your data. To use either device, you must start a workout in the app, as they don’t run continuously in the background.

When your workout is complete, each app gives you an analysis of your sweat data, including fluid loss, electrolyte loss, and sweat composition based on how much fluid you replenished during the workout. The hDrop app was a little more detailed breaking down electrolytes specifically into sodium and potassium. It also gives users a detailed recovery plan with how much fluid and electrolytes should be replenished based on your workout.

I was impressed by the real-time readings from each and the personalized recommendations based on your sweat profile. The Nix biosensor will even give you notifications mid-activity when it’s time to drink up.

I learned that I lose an average of 1.2 liters of sweat per hour that I run, which makes me feel more justified in guzzling as much as I now do. Finally, I didn’t have to guess how much to drink after the run, the devices told me, even going so far as to recommending an electrolyte product that best matched my sweat profile.

“Hydration tracking and sweat monitoring tools like Nix or hDrop can be useful, especially for athletes or people who need to manage hydration closely,” says Raj Dasgupta, MD, medical reviewer for the National Council on Aging. “However, they’re not necessary for everyone and should be used alongside your natural thirst cues,” he adds.

After following the recommendations of both the devices I was testing, I found I was less likely to bonk and instead felt more energized post-run. I was also less likely to need a nap (unless it was a particularly long run) and experienced less muscle soreness.

Other wearables coming to market soon promise to track your hydration as you go about your daily life, not just while exercising. Masimo, a medical device company you’d once have only seen in a hospital, is getting into the consumer wearables space with a sports watch that will include a hydration tracker, among other features. That watch is expected to launch in 2025.

Another, Geca, will track only hydration, continuously, all day. It promises to notify the user when they are dehydrating and give water intake recommendations. It is also slated to launch in the fall.

As for non-wearable tech, Betz recommends Hidrate Spark for the clients she works with. The insulated water bottle—created after the founders’ friend had a health scare—tracks water consumption and lights up to remind you to drink based on your pre-set hydration goals. And it can integrate with Apple Watch, Fitbit, and Garmin watches.

“It’s actually been proven to get people to drink more water,” says Betz.

Beyond devices

Not into experimenting and DIY-ing your health like I am? A much simpler method would be to see a dietitian, if you have access, to talk about any hydration concerns you have. A dietitian can take in all the factors discussed above and help you devise a plan. They’ll assess your body composition, your nutrition, and your medical history. They’ll order blood work and urinalysis. Then, they can help you come with a plan for how much you need to hydrate to stay well.

“Everyone’s hydration needs are different, so it’s important to listen to your body,” says Dr. Dasgupta.

If you’re able to listen to your body cues for hydrating, then you likely don’t need anything fancy to help you hydrate. But if ou struggle with drinking water—or getting enough electrolytes while exercising—then there’s nothing wrong with getting some help.