Floral and zesty key limes are much more delicate in taste compared to conventional Persian limes, and this key lime Italian soda recipe uses key lime simple syrup to create a flavorful, citrusy, and cult-classic soda flavor!

Two glasses of key lime soda sit on a wooden cutting board with straws in the glasses.

Making homemade beverages for over 10 years helps you to become super creative when it comes to making your own drinks. Homemade soda pops are one of my favorite drinks to make, because they’re so simple and fun.

This recipe was inspired by Stewart’s Fountain Classics soda, a store-bought brand of key lime soda. This homemade version is absolutely delicious, and when you top it with whipped cream, it tastes just like key lime pie! 🤤

why this key lime soda recipe works:

🍋 bright & zesty. Key limes have a super special flavor, opposed to conventional limes. They are more floral and much less acidic, which is why they’re usually featured in sweet recipes like key lime pie!

⏱️ quick & easy. Making your own soda is super easy, you don’t even need any specialty equipment. Sure, you can use a sodastream machine if you have it, but I prefer the even quicker (and cheaper) way of using sparkling water!

🥳 fun for the whole family. Homemade sodas are the perfect drink recipe to make for the whole family. It’s so easy to customize the flavor to your liking, and you have much more control over the sugar content of the drinks!

🛒 ingredients

key lime simple syrup – all homemade soda recipes need a flavor base, and this key lime simple syrup is what gives this soda the citrusy flavor packed punch of key lime! Take the time to make a batch of the simple syrup to get the best key lime flavor, trust me, it’s worth it!
soda water – this recipe calls for plain unflavored soda water, which is carbonated water. Sparkling mineral water has the addition of minerals, as the name suggests, which impact the taste of the water as well. In order to keep the flavor focus on the lemons in the recipe, I recommend sticking with unflavored soda water, or regular unflavored sparkling water (also sometimes called seltzer water).
ice – yes, yes, we are adding ice to the recipe ingredients because soda should be served ice cold! Use whatever ice you have on hand! Larger ice cubes will melt slower, and you can even use fun shapes or specially made key lime ice cubes!
whipped cream – whipped cream is optional, but it adds an extra layer of fun and flavor. If you like key lime pie, you’ll love adding whipped cream to this soda recipe!
key limes – fresh lime zest is a great optional garnish for this soda! It adds an extra burst of key lime flavor and a great dose of color on top of the whipped cream.

See the recipe card for the exact quantities.

🍳 instructions

Filling a glass with ice cubes to make a key lime soda.

Step 1: Fill your chosen glass with ice.

Hands from out of frame pour key lime simple syrup into a soda glass filled with ice.

Step 2: Next, add your key lime simple syrup to the glass.

Pouring La Croix into a glass to make a homemade key lime soda.

Step 3: Add in unflavored soda water to the top of the glass.

Hands from out of frame garnish a key lime soda with whipped cream.

Step 4: Top with whipped cream, if desired.

Garnishing a key lime soda with a slice of key lime.

Step 5: Garnish with a slice of a fresh key lime, or a dehydrated lime wheel.

Hands from out of frame are using a microplane to zest key limes onto a homemade key lime soda.

Step 6: Serve immediately.

Hint: If you want a stronger flavor, you can use as much as 2 ounces of syrup per serving!

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💡tips & tricks for getting it right

🍽️ serving tips

choose your glass

Glassware can make a big impact when you’re serving beverages! I love to use any cup that has at least a 12 ounce capacity.
Classic milkshake glasses, known as soda fountain glasses or soda shoppe glasses, are super fun for parties!

garnish

Garnish your sodas with a fresh sprinkle of key lime zest.
You can also garnish your sodas with a dehydrated lime wheel, a fresh key lime wheel or half of a key lime.

ℹ️ troubleshooting tips

Sure, this is a simple soda recipe. But! Things can definitely go wrong. Try these tips to make sure things go right, the FIRST time!

use the right sparkling water – make sure to use plain soda water, sparkling water, or seltzer water. You can also use club soda in a pinch, but it tends to have a bit of saltiness to it because of added minerals. Avoid using sparkling mineral water or tonic water.
start small with the syrup – I like to add just a bit less syrup than I think I’ll need. Start with a half ounce, or 1 TBSP. You can always add more syrup later, but it’s hard to dilute the flavor once it’s added.
too sour – if your soda is too sour or acidic, you can use a few drops of a saline solution for drinks to help balance out the tart lime flavor.

⚖️ scaling tips

Want to scale up the fun? This recipe is perfect for scaling up for a party! You can even use a 2-liter of seltzer water to make your own soda for parties or pool days!

🔆 top tip

Start by adding less syrup than you think you need, then taste your soda and add more if you like. It’s easier to adjust the flavor of the soda this way, instead of trying to dilute soda that is too sweet.

♻️ customize your homemade sodas!

Missing an ingredient? No problem. Check out these tried-and-true substitutions, or comment below with your question. I’m here to help you troubleshoot!

club soda – club soda can be used in place of sparkling water. Just be sure to taste your soda before adding in any saline solution because some brands of club soda add salt.
add herbs – add a sprig of rosemary or mint and muddle it into your glasses to impart a delicate herbal flavor. Or, you can even use an herbal simple syrup! Try this rosemary syrup or this sage syrup to add a layer of herbal flavor!
make it a cocktail – spike your soda by adding in an ounce or two of tequila, vodka, or rum! Gin would also go well with the citrus in this soda!

🧰 equipment needed & storage tips

drinking glass – I like to use a glass that have a 12 – 16 ounce capacity, so I can fit a whole can of sparkling water without having leftover. You can use a smaller more festive glass if you like! These soda can glasses are the ones featured in the photos. A special old fashioned milkshake glass would also make for a great presentation!
small measuring beaker or jigger these OXO nesting measuring beakers are so handy to use in so many recipes! They come in a graduated set perfect for measuring small amounts of liquid. You can also use a jigger if you have one.
straw – you can get really festive with your straws, adding a layer of fun for your friends and family. I love using silicone straws from GIR co. They clean up easy, are dishwasher safe, and come in so many fun colors. You can also use these fun paper straws that come in a variety of colors!
cocktail mixing spoon – a cocktail spoon is a mixing spoon with a longer than normal handle. This is super useful when mixing beverages. It allows you to mix easily without getting your hand into the soda!
Microplane zester – if you are topping your sodas with freshly grated key lime zest, you’ll need a Microplane zester grater to easily zest the limes.

🫙 storage tips

It is best to consume this soda shortly after drinking it because of the bubbles. If you are not serving it right away after making it, be sure to store it in an airtight container like these bottles from Bormioli Rocco that have stoppers (affiliate link).

💬 q+a

Do I need to make key lime simple syrup to make this soda?

Yes! Take the time to make the simple syrup first. Then you’ll be able to enjoy it in this soda and other key lime flavored drinks!

What kind of bubbly water do I need to use in this recipe?

Opt to use a plain, unflavored water like soda water, sparkling water, or club soda in a pinch. Be sure to check the label of your water to make sure that there is nothing added besides carbonation for the purest flavor.

If you make this recipe, please leave a review in the comments and a star rating!
⭐️⭐️⭐️⭐️⭐️
I read every single comment! I also love connecting on social media, so snap a pic and hashtag it #myrecipeforfun and tag me on Instagram, TikTok, or pin this recipe on Pinterest!

A homemade key lime soda sits on a wooden cutting board with a small pile of key limes next to the glass, and a bottle of key lime simple syrup in the background.

Key Lime Italian Soda (with Key Lime Syrup)

This homemade Italian key lime soda recipe uses key lime simple syrup to create a flavorful, citrusy, and cult-classic soda flavor! Key limes are more floral and less acidic in flavor than regular limes, so it’s the perfect way for the whole family to enjoy citrus season!

5 from 1 vote

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Course: Beverages, Drinks

Cuisine: American, Italian

Keyword: homemade soda, key lime

Prep Time: 5

Total Time: 5

Servings: Soda

Calories: 169kcal

Author: Lindsey Neumayer

Equipment

1 glass of choice
1 cocktail mixing spoon

Ingredients

1 ounce key lime simple syrup up to 2 ounces
8 ounces unflavored sparkling water such as La Croix or Polar Brand
ice
whipped cream optional
key lime for garnish

Instructions

Add ice. Fill your chosen glass with ice.
Pour syrup. Add your key lime simple syrup to the glass.
Add bubbles. Add in unflavored soda water to the top of the glass.
Top with whipped cream. Top with whipped cream, if desired.
Garnish. Garnish with a slice of a fresh key lime, or a dehydrated lime wheel.
Serve. Serve immediately with a straw.

Notes

Troubleshooting Tips

use the right sparkling water – make sure to use plain soda water, sparkling water, or seltzer water. You can also use club soda in a pinch, but it tends to have a bit of saltiness to it because of added minerals. Avoid using sparkling mineral water or tonic water.

start small with the syrup – I like to add just a bit less syrup than I think I’ll need. Start with a half ounce, or 1 TBSP. You can always add more syrup later, but it’s hard to dilute the flavor once it’s added.

too sour – if your soda is too sour or acidic, you can use a few drops of a saline solution for drinks to help balance out the tart lime flavor.

Nutrition Information

Servings: 1 Soda

Calories: 50mg

Total Fat: 50mg

Saturated Fat: 50mg

Trans Fat: 50mg

Cholesterol: 50mg

Sodium: 50mg

Carbohydrates: 50mg

Fiber: 50mg

Sugar: 50mg

Protein: 50mg

The information provided is an estimate based on an online nutrition facts calculator and actual nutrition facts may vary.