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Gillywater is a fun, Harry Potter inspired drink that looks a bit like something that crawled out of the sea, but tastes refreshingly delicious! In the Harry Potter books and movies, gillyweed is a magical plant that allows one to breathe underwater.
In undergrad school, I majored in biological sciences. It involved studying everything from physics, to chemistry, biochemistry, microbiology, evolutionary biology, genetics, and even psychology. I found the study of plants to be absolutely amazing.
And if you don’t already know this about me, I am a total nerd when it comes to Harry Potter! Herbology, essentially the wizard equivalent to botany, always struck my fancy.
In Herbology class, Professor Sprout taught Hogwarts students how to care for plants and use them for different potions and magical effects. It always reminded me of time before modern medicine when people used plants for their naturally-occurring medicinal properties.
So let’s make some gillywater!
Instead of the seaweed-like concoction that it is in the books and movies, this recipe results in what is essentially spa water. Sparkling water infused with fresh mint, cucumber, and lime makes the ultimate refreshing and rehydrating drink. It looks like a swamp though!
This is a fun drink to make for a Halloween party or a Harry Potter-inspired party.
What is Gillyweed in Harry Potter?
Gillyweed is a magical plant in the Harry Potter story. It was supposedly native to the Mediterranean Sea, and was described as looking like “slimy, grey-green rat tails”.
After eating gillyweed, a person would temporarily develop fish-like properties. Gills would form in the neck, allowing him or her to breathe underwater. Additionally, webbing between the fingers and toes would appear, which let the human swim easily under water.
In Harry Potter and the Goblet of Fire, Harry uses gillyweed to be able to breathe underwater in the Black Lake during the second task of the Triwizard Tournament.
You can read more about gillyweed on Harry Potter Wiki and Wikibooks.
How Does Harry Get Gillyweed?
The book and the movie are quite different in terms of how Harry gets Gillyweed!
In the book, Dobby gave Gillyweed to Harry after hearing a staged conversation between Bartemius Crouch Junior (who used Polyjuice Potion to disguise himself as Alastor Moody) and Professor McGonagall.
In the movie, Neville gave Gillyweed to Harry after Bartemius Crouch Junior (disguised as Alastor Moody) gave Neville a book on Magical Water Plants of the Mediterranean.
Gillywater Recipe
With just four ordinary ingredients and no cooking required, this gillywatwer recipe is very easy to make!
Breaking It Down
Ingredients Explained
In this section I explain the ingredients and give substitution ideas where applicable. For the full recipe (including the ingredient amounts), see the recipe card below.
- Sparkling water
- Cucumber
- Mint
- Lime
Step-by-Step Instructions: How to Make Gillywater
Step 1: Spiralize the Cucumber
Or if you don’t have a spiralizer, you can use a vegetable peeler to get thin strips (both the peel and the flesh of the cucumber are fine for this).
Step 2: Peel the Lime and Squeeze the Juice
We will use both the lime juice and rind for this recipe. The peels infuse the water with even more lime flavor, and they add to the swampy, seaweed-like vibe we’re going for.
Step 3: Mix and Enjoy
Add everything to a pitcher. (TIP: Be careful not to over-stir so the water doesn’t lose its carbonation.) Enjoy!
Tips For Success
- If You Don’t Have a Spiralizer: You can use a vegetable peeler (on the peel and the flesh) to get cucumber strips.
- For the Lime Peels: Use organic limes if possible because the peels will be going into the drink. Scrub the outside of the limes, and then use a vegetable peeler to cut off strips of peel (try to get as little of the white as possible because it’s bitter). The lime peels infuse the water with more flavor, but don’t eat them.
- Sparkling Water: You can use any flavor of sparkling water you like. If you use unflavored, unsweetened sparkling water, this drink will have a lime, mint, cucumber flavor profile (think: spa water). If you like flavored water, lemon-lime sparkling water is a good choice. Or you can use sweetened sparkling water or lemon-lime soda (such as 7UP or Sprite) if you like your drinks on the sweet side or if you’re making this for kids.
- Adult Version: If you want to make an alcoholic version of this drink, add a shot of gin to each serving. The herby, piney, citrusy notes of gin pair beautifully with the other flavors here. Or if gin isn’t your thing, you could add a shot of vodka instead.
Frequently Asked Questions
No! Gillyweed is straight out of the amazing mind of J.K. Rowling. It may have been inspired by seaweed, but this plant is completely fictitious.
In the Harry Potter books and movies, it seems like gillywater was made of water + gillyweed. This gillywater recipe contains sparkling water, cucumber, mint, and lime! Spa water, anyone?
In The Wizarding World of Harry Potter at Universal Studios, Gillywater is just regular, unflavored, non-carbonated water. However, you can buy an elixir or potion (aka a flavored syrup) to add if you like.
The version we’re making here tastes like healthy spa water! And if you prefer a sweet drink, you can use lemon-lime soda instead of unflavored sparkling water.
More Harry Potter Drinks to Make
- Polyjuice Potion – this drink even changes color!
- Butterbeer – make it frozen or regular, they’re both delicious
- Harry Potter Foods – more drinks and food inspired by Harry Potter
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Gillywater Recipe
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Ingredients
- 1 quart sparkling water (see Notes)
- 2 cups spiralized cucumber (see Notes)
- 4 sprigs fresh mint
- 1/2 cup fresh lime peels (see Notes)
- 2 tablespoons fresh lime juice
Instructions
- Add all ingredients to a large pitcher.
- Stir gently. (TIP: Be careful not to over-stir so the water doesn’t lose its carbonation.)
- Serve chilled.
Notes
- Recipe Yield and Serving Size: This recipe makes 32 ounces of gillywater, which is enough for 4 (1-cup) servings.
- If You Don’t Have a Spiralizer For the Cucumber: You can use a vegetable peeler (on the peel and the flesh) to get cucumber strips.
- Lime Peels: Use organic limes if possible because the peels will be going into the drink. Scrub the outside of the limes, and then use a vegetable peeler to cut strips of peel off (try to get as little of the white as possible because it’s bitter). The lime peels infuse the water with more flavor, but don’t eat them.
- Sparkling Water: You can use any flavor of sparkling water you like. If you use unflavored, unsweetened sparkling water, this drink will have a lime, mint, cucumber flavor profile. If you like flavored water, lemon-lime sparkling water is a good choice. Or you can use sweetened sparkling water or lemon-lime soda (such as 7UP or Sprite) if you like your drinks on the sweet side or if you’re making this for kids.
- Adult Version: If you want to make an alcoholic version of this drink, add a shot of gin to each serving. The herby, piney, citrusy notes of gin pair beautifully with the other flavors here. Or if gin isn’t your thing, you could add a shot of vodka instead.
Nutrition
Nutritional information is automatically calculated and should be used as an approximate.
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This post was first published on An Edible Mosaic on October 21, 2022 and updated on October 16, 2026.
I’m the writer, recipe developer, photographer, and food stylist behind this blog. I love finding the human connection through something we all do every day: eat! Food is a common ground that we can all relate to, and our tables tell a story. It’s my goal to inspire you to get in the kitchen, try something new, and find a favorite you didn’t know you had.
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