Introduction: The Cold Seep Coffee Maker (<10 Min to Get Started!)

About: Tech Editor, Mad Professor

You enjoy Coffee as a Cold Brew or Cold Drip and you are looking for a simple and compact solution to produce some for yourself? Then I welcome you to my very first instructable, The Cold Seep Coffee Maker. I hope you'll enjoy it!

What we're building here is actually a little system that is kind of a cross-breed between Cold Brew and Cold Drip. The way it is designed, it produces a constant trickle of water through the coffee, without emerging it, so I called it "Cold Seep". Taste-wise you'll get a mild, slightly sweet coffee with less caffeine than your regular hot coffee. Add some (plant based) milk and you get a delicious iced coffee blend without needing to add sugar.

The Cold Seep Coffee Maker can be constructed easily. You'll have your first brew going in less than 10 minutes. Also, there's a good chance, that everything you need can already be found in your kitchen. And if not, it can be obtained easily in the next store that sells common houselhold items.

Step 1: Basic Requirements

Now let me give you a run-down of what you need to make this:

  • a glass that can hold about 250 ml/~8 fl. oz. of liquid, preferably of a more narrow diameter
  • a plastic cup (preferably BPA free) with a conic shape, which you should be able to slide into the upper part of the glass
  • a thin screwdriver or something else to make tiny holes of about 1-2 mm in diameter
  • aluminum foil
  • optional: a thick rubber band

And these things are required for the actual brewing:

  • coffee (obviously. Coarse grind preferably, see photo)
  • 2 small sized paper coffee filters that fit nicely into the cup
  • ice cubes
  • two spoonfuls of warm water (20-30 ml or ~1 fl. oz)
  • optional: one permanent filter to replace one the disposable ones

Step 2: Fixing Up the Cup and the Glass

Finding a cup and glass that go nicely together is probably the most difficult step of this whole procedure. However, you can give yourself some leverage by utilizing the rubber band. If it turns out that your cup slides into the glass by a too great extent - as it was in my case - use the rubber to have it fall into place earlier.

This is important, because we do not want the coffee grind to be submerged in the brew once the glass starts filling up.

Now once you know that glass and cup will play together nicely, it's time for some easy handicraft. Use the screwdriver or any other tool of your choice to create a few holes at the bottom of the cup. In my case, five holes around the center did the trick.

Step 3: Time to Brew!

Now that your Cold Seep Coffee Maker is actually ready, we can now get going with the actual brewing process.

First, pre-wet one of the paper filters with a bit of water. This will ensure that it gets a bit sticky and it also won't suck up some of the precious coffee we're going to produce.

Then fit it into the cup and try to have its rim stick to the wall as good as possible.

Next, add the coffee grind. I usually fill up my filter to about two thirds. You may want to experiment with the amount and the coarseness of the grind. I wouldn't recommend using a very fine grind, because this raises the risk of clogging up. And since this is not a precise process, you'll likely also end up with more grind residue in your brew.

Once the coffee grind is in place, gently use a spoon to push the filter to the bottom.

Then add the second filter on top of it (you can use a permanent filter here, if you have one) and insert ice cubes until the cup is full. The second filter is mainly there to prevent the ice from directly coming in contact and immediately freezing up the coffee grind.

Step 4: The Kickstart

We're almost ready now. However, to get the brewing process started faster and to prevent the ice to freeze through the filter, take two spoonfuls of warm water and evenly pour it over the ice cubes. This will get the cubes to start thawing and create a tiny stream of water going through the grind and then dropping into the glass.

To prevent dust or insects from ending up in our precious drink, cover the top of the cup with aluminum foil.

It will take a few hours until the ice cubes have fully melted and your Cold Seep is ready. Depending on how many ice cubes you managed to fit into the cup, the yield will probably be around 200-220 ml (around 7 fl. oz). To get going again, just throw away the paper filters and the used coffee grind and give the cup a quick rinse.

At a room temperature of about 20 degrees Celsius (68F) I can create two to three glasses of cold coffee a day, provided that I'm home most of the time.

Smoothie bottles are perfect for storing these portions. The Cold Seep should stay tasty and consumable for up to two weeks when stored in the fridge.


Step 5: Stepping Up the Game

Satisfied with the result, but you want a more efficient system to produce larger quantities? Well, here we go.

You'll need:

  • again a suitable plastic vessel - a cone-shaped measuring cup works really well
  • a bigger kind of glass vessel - I used a caraffe with a capacity of one liter
  • a metal tea filter, preferably one with a lid. find one with a diameter of 6 cm (~2,4 inch)
  • paper filters (larger ones this time)
  • the optional rubber band

The main difference is, that the vessels might be harder to obtain, but still there is a good chance you'll find suitable ones in a well equipped household store. The total cost for the measuring cup, tea filter and caraffe amounted up to about 20 dollars.

The whole concept works just like the previous iteration. However, the vessels are larger and the paper filter containing the coffee grind has been replaced with the tea filter. The second paper filter is still necessary, because usually the tea filter would otherwise allow water to pass by on the side. But since the paper filter is not in contact with the grind anymore, you may reuse it one or two times.

The construction I created yields about 300-350 ml of cold seep coffee per run while the amount of grind used is roughly the same. So I am using up less coffee and paper filters without compromising on taste.