Filtering tonic water with the Espro Press


Homemade tonic water is delicious. Homemade tonic water is also a real pain to make. The natural source of quinine, cinchona bark, usually comes in a very fine powder that’s difficult to filter out of the finished product. It can take hours to drip through coffee filters and leaves a sticky mess on the counter if you’re not careful. Difficulty of filtering is the number one reason many people I know buy commercial tonics, many of which are now quite good, instead of making their own. But there are still reasons one might like to make a homemade tonic, including lower cost and the freedom to flavor it exactly how one wants.


Happily, I recently stumbled onto a solution that makes filtering tonic water easy. One of the hit new products at this year’s Specialty Coffee Association of America show was the Espro Press, a new kind of French press developed in Vancouver, Canada. Two things make this press unique. One is that the brewing chamber is enclosed by double wall vacuum-insulated stainless steel, so that it retains heat very well. The second is that it uses not one but two filters on the plunger. The primary filter is much finer than that on a standard French press and the secondary filter is finer still. This allows it to brew French press coffee without the “sludge” that the brewing method tends to leave in the bottom of the cup. It makes a nice cup of joe and I’ve been using it fairly often for my morning coffee the past few weeks.



I realized that the same things that make the Espro Press good for brewing coffee could also make it good for making tonic water. The heat retention should make it possible to brew the entire tonic in the press without need of a stovetop pan. And the dual filters, if they don’t get clogged with cinchona, would be perfect for removing the fine powder. The Espro sold out quickly at the show but luckily I was able to buy their demo press. I brought it back to the bar to try it out. The experiment worked and I have to say that I was a little more excited than a grown man should be when the first runnings of nearly perfectly clarified tonic came pouring out of the press.

What follows is a sample recipe for making tonic with an Espro Press. The proportions aren’t meant to be definitive, as this isn’t something I’ve needed to make consistently for a menu item. My usual approach to tonic is to riff off a standard recipe with whatever citrus and spices I happen to have on hand. A couple recipes that I often work from are this one from Kevin Ludwig in Imbibe magazine and this one from Jeffrey Morgenthaler (whoever he is). Two notes before proceeding:

Note 1: Quinine has effects on the body and can be dangerous in high doses. Read up on the possible adverse effects before proceeding. I’ve never heard of anyone coming to harm from homemade tonic water but I’m a bartender, not a doctor. Proceed at your own risk!

Note 2: Contrary to what some recipes say, add the sugar and citric acid after you filter out everything else. These need to be dissolved but they don’t have flavors that need to be extracted with heat. Adding them early just makes the mixture more viscous and more difficult to filter. Make life easier and add them at the end.

That out of the way, here’s one of the recipes I used to make tonic with the Espro Press:

4 cups hot water
3 cups sugar
6 tablespoons citric acid
3 tablespoons cinchona bark
zest of one grapefruit
zest of one lime
6 oz grapefruit juice
2 oz lime juice
1 teaspoon brown mustard seeds
1 teaspoon dill seeds

Step 1: Pre-heat the Espro Press with hot water so that the temperature will remain stable when you brew the tonic.

Step 2: Discard the water and place the cinchona bark, citrus zests, citrus juices, and spices into the press. Add the four cups of hot water and stir. Place the plunger on top of the press to seal in heat and let sit for twenty minutes.

Step 3: Lower the plunger to filter the tonic. The bark will offer significant resistance so you can’t just Hulk Smash the plunger into the chamber. Proceed slowly, using your weight to gently press the plunger down.

Step 4: Pour as much of the tonic out of the press as possible. When it stops flowing, rotate it and pour from a different angle; I think this gets around some blockage caused by the cinchona powder. Doing this a few times will maximize the yield.

Step 5: Beneath the filters there will still be some liquid remaining with all the powder and spices. You can filter this with some more labor-intensive method or simply discard it. This recipe being all about making things easy, I opt for the latter.

Step 6: Add the sugar and citric acid to the tonic to make a syrup. Stir to dissolve and pour into a bottle for storage.

That’s all there is to it. The syrup is ready to enjoy with soda water or mixed into a classic Gin and Tonic:

1 1/2 oz gin
3/4 oz tonic syrup
lime wedge

Combine all ingredients in a glass with ice, squeeze in the lime wedge, and stir.

A few additional notes…

I’ve made two batches of tonic with the Espro Press. It’s easy to clean afterwards and I don’t think repeated use would be a problem. However I haven’t put it up to the rigors of regular use in a busy bar, so if you’re buying one for that purpose I can’t guarantee that it will hold up. If you’re buying one for home use it should be fine and you’ll get a stylish coffee brewer too.

The Espro Press comes in two sizes. I bought the larger one, which at 30 oz is large indeed. The 8 oz one is intended for single servings of coffee. I haven’t tried it out for tonic. A list of retailers selling the Espro Press is here. It’s also available on Amazon (large; small). Cinchona powder can be purchased in bulk at herb shops such as this one.

Finally, in a surprising bit of synchronicity this isn’t the only post published this week about using coffee equipment to filter tonic water. Camper English of Alcademics features a method from Kevin Liu for using an Aeropress to accomplish the same thing. Check out that post too and keep following Camper’s blog for additional ideas.

[Photos of the Espro Press courtesy of Espro.]


6 thoughts on “Filtering tonic water with the Espro Press”

  1. Gin and tonics are the perfect drink in my opinion, never knew you could make tonic water yourself though! The Espro presses are awesome, have 2 small and just got my large from Venia Coffee ( on the list you posted). Going to order some cinchona bark in the morning to try. Thanks for putting this post together.

  2. ciao jacob, great article. thinking about purchasing the espro. i’m curious about the g&t in the photo next to the syrup…can you tell me the quantity of gin, h20 and syrup used? how did it taste? the color doesn’t look too dark so it seems workable for a commercial bar. cheers, eric

Comments are closed.