Mark One’s Pryme Vessyl is an iPhone-connected cup that’s designed to track your daily liquid intake, making sure you’re at your optimal hydration level. According to Mark One, hitting an ideal hydration level can increase your energy level and improve your mental balance.

Paired with an accompanying app, Pryme Vessyl calculates a user’s hydration needs based on height, weight, activity level, and other factors, making sure that intake level is met by measuring each sip of water or liquid through accelerometers in the cup itself. Hydration needs change from day to day, so the goal of the Pryme Vessyl is to make sure users are getting enough hydration as activity level shifts.

The idea is to drink all of your liquids — coffee, tea, water, juice — out of the Pryme Vessyl to get an overall picture of liquid intake and track any deficits.


Mark One’s Pryme Vessyl features a clean design that looks like it could have come out of the Apple design lab. It has a sleek white exterior that’s soft and smooth to the touch with a glass interior. There’s plastic at the top of the cup and the lid, which fits into the top, is also plastic, so it’s not going to be a good purchase for those who prefer to avoid plastic drinking vessels entirely.

The lid of the Pryme Vessyl is problematic because it can be difficult to remove. Pressing with a thumb on the lid slides it over to reveal an opening to drink from, and pulling up on the extra plastic pries open the lid. It takes a lot of force to open the lid of the Pryme Vessyl, but Mark One says it will loosen up over time.

Once I learned the trick for opening the lid, I found it simple to do, but it does require pulling so hard in an upward motion that it feels I’m going to break something. Popping the lid off needs to be done every time the cup is filled, and because it only holds 16 ounces, it needs to be filled frequently if you drink a lot of water.

Drinking from the Pryme Vessyl is like drinking from any travel cup with a lid. The opening is small so you can’t get much liquid per sip, and it can be awkward to drink from because the top part doesn’t fully come off. The lid opening is not large enough to fit a straw, and for the first several days of use, I noticed a plasticky taste.

With the lid snapped into place, the Pryme Vessyl looks like it should be watertight, but it’s not. If you put it in a backpack or bag and it tips, it’s going to leak. Because it’s lined with glass, the Pryme Vessyl is heavier than your average travel cup, but it does support both hot and cold liquids and it can be used with or without the lid in place. There’s no real insulation aside from the glass, so it’s not going to keep cold drinks cold or hot drinks hot and it will feel warm or cold based on what’s inside it.

This line is where the LED is located

An LED on the side of the cup can be pressed to display a line representing how close you are to reaching your daily water intake goal, and it also lights up when charging the battery. I found myself wishing the LED indicator did more, like letting me know when the cup disconnected from Bluetooth or how much water was left.


There’s an accelerometer built into the Pryme Vessyl, which is what tracks the water level in the cup and detects whenever a sip is taken so it can be recorded. Built-in Bluetooth transmits that data to the iPhone, keeping tabs on all of the liquid consumed through the cup. It tracks as little as 0.5 ounces at a time, which is a relatively small sip.

Every couple of days, the Pryme Vessyl inexplicably disconnected from my iPhone even though it said Bluetooth was still enabled, and I had to go through an entire reset process to fix the connection. When it isn’t able to connect to the iPhone, the cup will store sips and upload them later, so it doesn’t need to be used alongside the iPhone at all times and data isn’t lost if a connection is lost.

When walking around with the Pryme Vessyl, transporting it in the car, or washing it, I had errant sips added to my liquid intake totals. Mark One says an update is in the works to fix this problem and improve the algorithm that detects when a sip is taken, but it accounted for several inaccuracies.

Phantom sips can be deleted by pressing and holding on the drink in the timeline screen, which is how any liquid can be deleted. This isn’t exactly intuitive — the Vessyl needs an app design that makes hidden features like this more apparent. The Vessyl can also be turned off when washing or traveling, another feature that’s not obvious because it’s done through a teeny tiny hole in the bottom of the cup.

With an accelerometer, Bluetooth, and other electronics inside, the Pryme Vessyl needs to be hand washed — it’s not dishwasher safe. It’s also not microwave safe and Mark One says it shouldn’t be placed in the freezer, but it can go in the refrigerator for short periods of time.

The Pryme Vessyl needs to charge every day to two days, and charging is done inductively through a metal base on the cup that attaches to an included coaster. It’s definitely not convenient to have to charge a cup, but I put the coaster on the table where I work, which made the charging process relatively painless. It generally took just under two hours to fully charge the cup.


Like most smart objects, the Pryme Vessyl interfaces with the iPhone using an app (there’s also an Apple Watch add-on). Available for free in the App Store, the Pryme Vessyl app is used to track how much liquid is consumed during the day. Using input including height, weight, age, and activity level, the app calculates an ideal hydration level for you.

Based on activity information pulled in from Apple Health, Jawbone, and/or Fitbit, it adjusts hydration calculations on an ongoing basis. Sleep schedules are also input so it knows when to track liquid intake, and it should be noted that when the app thinks you’re sleeping, it will not track sips at all. Mark One says this is because nighttime water intake disrupts sleep, but this is inconvenient for people who would like to track overall liquid intake 24 hours a day.

Each sip of water from the Pryme Vessyl is tracked in the app and fills up a circle that takes up most of the main view. The circle represents hydration level and the idea is to drink enough liquid to stay at your “Pryme” for the entirety of the time you’re awake.

Scrolling downwards displays a timeline of the exact number of ounces consumed at each point during the day (as tracked by the cup), but the main circle view of the app doesn’t give a picture of overall ounces. All it does is let you know whether or not you’re at your Pryme, aka optimal hydration level. In landscape mode, the timeline is displayed as a line graph.

Tracking from the Pryme Vessyl is automatic, but drinks not consumed through the cup can be entered manually. When entering a drink manually, the app offers up three preset ounce options, but there’s a hidden option to customize the amount consumed at the time it was consumed at. A similar option exists for entering activity.

The app, while pretty, is overly simple and surprisingly unintuitive, mainly because there are no instructions to let you know how to manage the features. There’s no obvious way to see the total ounces consumed, but hidden in a weekly overview menu (which doesn’t make it obvious you should tap), there’s a way to see full water consumption for the day.

One of the biggest shortcomings in the app is its inability to store more than a week’s worth of water consumption data. Because it links to the Apple Health app, which supports the tracking of liquid, there’s a way to get data for longer periods of time, but the app itself only displays one week of information. When tracking hydration to improve health, most people likely want historical data readily available.

The Pryme Vessyl app is designed to deliver notifications, but in my experience, these were inconsistent and not useful. I reliably got one notification each morning, but notifications during the rest of the day were sporadic. On one day when I fully met my Pryme goals for most of the day, I received five notifications reminding me to stay at my Pryme or take another sip of water, and on another day where I drank next to nothing from the cup, I received no notifications.

I expected a smarter app to go with a smart cup, perhaps letting me know the times of the day when I needed more hydration based on historical activity information or data on how my personal hydration needs were being calculated on a day to day basis, but it didn’t do much more than wishing me a good morning or occasionally telling me to take another sip.

On the plus side, the app used very little battery life on my iPhone despite being connected to the Pryme Vessyl and transmitting data over Bluetooth all day long.

Bottom Line

Using the Pryme Vessyl to its full potential is a compromise because you have to hassle with drinking liquids exclusively through the cup, fuss with connectivity problems, and charge yet another device. Liquid consumption tracking is accurate most of the time, but you’re going to have to deal with inaccuracies from time to time, which require time and attention to watch for and fix.

Over the time that I tested the Pryme Vessyl, I found it surprisingly inconvenient to pour all of the liquid I drank, from regular water to tea to cans of sparkling water, into the cup. I had the option to add liquid manually when I didn’t feel like drinking out of the Pryme Vessyl, but when I got into the habit of doing that, I wondered why I wasn’t using a simple water tracking app that does away with the need to drink from a single cup.

Even on days when I was active, my water needs didn’t shift a lot and I didn’t notice the cup telling me to drink much more than I did on an average day, so the Vessyl didn’t do enough for me to justify its cost. Since I already drink a lot of liquids during the day, I didn’t notice any measurable difference consuming water from the Vessyl and staying at my “Pryme.”

If you’re someone, like me, who already drinks a lot of water, tea, juice, and other liquid throughout the day, you don’t need the Pryme Vessyl. If you’re someone who has a hard time remembering to drink enough water in a day, whether because of a busy schedule, a preference for soda, or another reason, I guess the Pryme Vessyl has the potential to be a decent investment.

A person who is regularly dehydrated and adopts the Pryme Vessyl will undoubtedly notice the health benefits that come with drinking more water throughout the day, and if you’re paying $99 for a cup, I bet you’re going to use it.

It’s worth noting that water intake can be tracked much more cheaply and smartly through a simple water tracking app available from the App Store, which is a good starting point for anyone who wants to up their water intake. Liquid consumed will need to be entered manually, but there’s no charging, no setup, no fussing with Bluetooth disconnects, and no need to drink out of just one vessel.


  • Accurate liquid intake tracking in most conditions
  • Encourages more water consumption
  • Works with hot and cold liquids
  • Apple-style design
  • App uses little battery life


  • It’s another device that needs frequent charging (every two days)
  • Only holds 16 ounces
  • Not as easy to clean as a regular cup — not dishwasher safe
  • Loses Bluetooth connection a lot and requires resetting
  • Doesn’t store more than a week’s worth of data
  • Inconsistent notifications
  • Not watertight, so it leaks

How to Buy

The Pryme Vessyl can be purchased from the Vessyl website for $99 and $10 shipping. It is also available from and in Apple retail stores for $99.95.

Note: Mark One provided a Pryme Vessyl to MacRumors free of charge for the purposes of this review. No other compensation was received.

Tags: Pryme Vessyl, Mark One

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