I Asked My Coworkers To Try Diet Coke From A Glass Bottle, Plastic Bottle, Can, And McDonald's Fountain To Find Out Their Favorite

Over the past year or so, we've truly witnessed a revival of Diet Coke — a Renaissance, if you will. Fellow DC lovers (nope, not the comics) are probably familiar with the social media craze and even "recipes" for elevating everyone's favorite afternoon pick-me-up. The peak really hit in 2023, when it became impossible to escape the videos of someone opening a can of crispy Diet Coke, dumping in a packet of crystallized lime juice, and stirring it around with a glass straw before taking that satisfying first sip.

Bottles and cans of Diet Coke lined up on a counter
Ross Yoder

Personally, I've always been a Coke Zero gal through and through (and you know what? I might still be), but the Diet Coke girlies definitely got to me. Before I knew it, cracking open a 2 p.m. Diet Coke in the office became somewhat of a ritual that I always looked forward to. Then something tragic happened: Caffeinated sodas began disappearing from our fridge, and yes, that included my beloved Diet Coke.

Bottles and cans of Diet Coke in a fridge with an "x" through them

Note that this is a total exaggeration and far from a tragedy. Our fridge gets stocked with plenty of sparkling water that we all love. I'm just overdramatic and under-caffeinated.

Claudia Santos

After simultaneously witnessing all the Diet Coke discourse on my feed and chatting with my coworkers about our mutual sadness over no longer having it, I realized that we all take this beverage very seriously. Specifically, people tend to have strong opinions when it comes to the different vessels Diet Coke comes in: bottles, cans, fountains, etc.

Cans tend to take over my feed, but I often hear people's preference for McDonald's fountain Coke/Diet Coke in particular. So as someone very interested in seemingly pointless data, I needed to know once and for all which one ranks supreme, and whether any of us can even tell the difference among these.

So with the incredible help of my coworker Ross, I set out to conduct an office-wide blind taste test with four types of Diet Coke: in a plastic bottle, a glass bottle, and a can, as well as one from the McDonald's fountain.

The four different types of diet coke lined up on a table
Ross Yoder

Each Diet Coke was assigned a number and then poured into 3-ounce cups, which we labeled. Our testers were then asked to try the Diet Cokes one by one, guess which container it came in, and give a final ranking from their favorite to least favorite.

Four mouthwash cups on a cutting board, each filled with Diet Coke from different vessels

Before we dive into the results, we need to have a chat about McDonald's. McDonald's Diet Coke is usually seen as top tier, and per their own website's FAQ section, this is why: "The water and Coca-Cola syrup are pre-chilled before entering our fountain dispensers with the ratio of syrup set to allow for ice to melt." Not going to lie, this kind of blew my mind. I always knew that McDonald's made Coke the "traditional" way, using syrups, but never knew they considered how ice would dilute the drink.

They also use filtered water, and of course, there's the straw, which is "wider than a typical straw so all that Coke taste can hit your taste buds."

With all that Diet Coke science in mind, we came up with a McDonald's plan. First, order two large Diet Cokes with no ice (I messed this up the first time, oops). Second, dilute the Diet Coke with about 1 ounce of water to replicate the dilution from melted ice. Last, pour it into SodaStream bottles to prevent it from going flat.

A McDonald's ordering screen, McDonald's Diet Coke being poured into a pitcher, and then poured into a SodaStream bottle

Despite my mistake of ordering ice, I wasn't carrying the Diet Coke long enough for it to melt, so I still stuck to the original plan of diluting it.

Claudia Santos

While the SodaStream bottles were meant to keep in the bubbles, we definitely ran into some issues. I picked up the sodas in the morning, and they immediately looked flat as I was pouring, so I had little hope for how they'd hold up. I also realized I definitely needed more. Now, worried that 1) we wouldn't have enough Diet Coke and 2) our taste test would be thrown off by flat soda, I went to a different McDonald's and grabbed two more. Again, they were flat.

Two SodaStream bottles full of Diet Coke

We knew we'd lose some bubbles with this storage method, but being handed relatively flat soda from the start made it almost impossible to keep it fizzy.

Ross Yoder

During our taste test, we came to the conclusion that we couldn't justify serving soda that was this flat. So, again, we grabbed two more Diet Cokes from yet another McDonald's (Times Square is definitely not short on them). This location was a little more fizzy than the first two (and served to our remaining testers almost immediately), but it still didn't seem to change people's opinions about the McD's Diet Coke.

A McDonald's storefront in NYC

Whew, what an emotional roller coaster. With our McDonald's fiasco finally settled, here is our official Diet Coke ranking from worst to best.

4. McDonald's Fountain

The four different types of Diet Coke lined up on a table, with an arrow pointing to the SodaStream bottles

This probably comes as a shock to no one, considering our McDonald's drama. But given that we went to three different locations and each one had some seriously lackluster fizz, this feels like a fair rating.

Ross Yoder

Not only did our testers have an issue with McDonald's Diet Coke being flat, but they also found it to be overly sweet. One noted that they "could taste the fountain syrup," and someone else thought it could be mistaken for regular Coke because of how sweet it was. We even had someone describe it as "bouba" (I won't get into the kiki-bouba effect, but it was probably the most accurate description I'd heard all day).

A tester drinking a cup of Diet Coke and saying it's "by far the sweetest of the bunch"

The "syrupy" flavor was likely a dead giveaway, since a majority of the testers accurately guessed that this was McDonald's. However, the lack of fizz made many of us think this was one of the other three; no one expected McD's to be the flattest of the bunch. If anything, we all thought it would have some of the best fizziness. Alas, we were left disappointed.

A pie chart showing people's Diet Coke vessel guesses, with the majority, almost 36%, guessing McD's fountain
Claudia Santos


One and a half Diet Coke emojis representing rating stars
Claudia Santos

3. Glass Bottle

The four different types of Diet Coke lined up on a table, with an arrow pointing to the glass bottle

This was gravely disappointing for me because Diet Coke in a glass bottle is the fun treat I get myself whenever I spot it. I personally ranked it as my favorite during my own taste test. Sadly, the numbers don't lie, and the reviews were mixed.

Ross Yoder

A few of our testers thought it had that "classic" Diet Coke taste. Some thought the flavor was flat, and when it came to fizziness, they were split. Some found it to have a good fizz, while others thought it was flatter or even watered down. Personally, I found the fizziness to have a nice middle ground: It was fizzy without weirdly hurting your nose from being over-carbonated. But I definitely understand that it didn't meet everyone's bubbly Diet Coke expectations.

A tester drinking a cup of Diet Coke and saying it "tastes like a classic Diet Coke that I have every day — good carbonation and flavor"
Ross Yoder

Funnily enough, half of our testers thought this was the plastic bottle. My guess is that plastic bottles are thought to be a little less fizzy, plus the glass bottle still had the "classic" taste most people expected. It's also unsurprising, given that glass bottles aren't always the easiest to find (petition to change this, please), so people are a little less familiar with the taste.

A pie chart showing people's Diet Coke vessel guesses, with 50% guessing plastic and only 7% glass
Claudia Santos


Three and a fifth Diet Coke emojis representing rating stars
Claudia Santos

2. Plastic Bottle

The four different types of Diet Coke lined up on a table, with an arrow pointing to the plastic bottle

I know, I'm just as shocked as you are. Plastic bottles tend to get a lot of heat for being lower quality, but people really seemed to like it. The word "classic" was definitely thrown around with this one the most.

Ross Yoder

Most of the testers thought there was a nice level of fizziness, and again, a few recognized the classic Diet Coke flavor. One person described the flavor as "smooth and light," and I'd have to agree. I definitely found it to have a lighter flavor than the others (especially McDonald's...), although some people pointed out that it was a little sweet.

A tester drinking a cup of Diet Coke calling it "smooth and light — would be good with rum!"

I was kind of surprised that only one person pointed out that this tasted plasticky! Even going into my taste test, I thought the plastic-like taste would be something I'd immediately recognize, but it wasn't. I do think it's likely something you'd notice more if you were drinking straight from the bottle.

Ross Yoder

Guesses were pretty split, but a majority still thought this was a glass bottle, even yours truly. I think the "lighter" flavor, combined with a decent level of fizziness, fooled a lot of us into thinking it was in a higher-quality container. This, again, is pretty fascinating, considering that people would normally rank a plastic bottle at the bottom of their list.

A pie chart showing people's Diet Coke vessel guesses, with 21% guessing plastic
Claudia Santos


Three and four/fifths Diet Coke emojis representing rating stars
Claudia Santos

1. Can

The four different types of Diet Coke lined up on a table, with an arrow pointing to the can

The canned Diet Coke that's all over our For You pages emerged victorious. Honestly, I'm not mad about it — you just can't beat that satisfying sound of opening a crisp can. From flavor to fizziness, people loved this one.

Ross Yoder

"Main character energy," "summery," "crisp" — yeah, this was definitely a favorite. The fizziness from the can really smacks you in the face, and despite having been in an open container that couldn't be resealed between testers, it didn't lose its fizz. Whereas McDonald's was "bouba," the canned Diet Coke was aptly described as "kiki." I took one sip and immediately said, "Whoa, zigzaggy." And if none of those adjectives means anything to you, think of it as the one you'd want to pour over ice with a little lime on a hot summer day.

A tester drinking a cup of Diet Coke and saying "Number four has main character energy"
Claudia Santos

Even though guesses were still relatively split, most people guessed this was the can. One tester literally took one sip and said, "Yup, that's a can" — it was very impressive. This is likely what Diet Coke connoisseurs often reach for, especially since it's what's readily available in offices, restaurants, delis, planes, etc.

A pie chart showing people's Diet Coke vessel guesses, with almost 36% guessing can
Claudia Santos


Four a half Diet Coke emojis representing rating stars
Claudia Santos

So, yes, canned Diet Coke technically won and was certainly tied with McDonald's when it comes to ease of recognition. But (and this is a very big but) I'm hesitant to declare it the supreme Diet Coke. With the exception of McDonald's — which clearly ran into some mishaps — there wasn't a definitive consensus for each Diet Coke.

All in all, the main takeaway I got from this taste test was that whatever you choose to drink your Diet Coke out of is really personal preference. Case in point: I will always reach for a glass bottle over a can because I like a medium-level fizz plus crisp flavor.

And will I ever pass up a McDonald's Diet Coke when I'm in the middle of a road trip and deserve a fun treat? Absolutely not.

Let us know which is your favorite Diet Coke in the comments! Or maybe there's a secret fifth option we need to try next.