Why Is My Chemex Coffee Cloudy? 5 Chemex Brewing Mistakes

chemex pour over coffee maker

Chemex coffee makers make exquisite cups of coffee with delicious flavors and aromas. This manual pour-over coffee maker has a funnel neck and thick filter papers. The result is a clean brew while the custom filters remove any hint of bitterness. 

Mistakes in the brewing process can cause your Chemex coffee to become cloudy and bitter. Some of the biggest concerns include using unfiltered water, overground beans, or a dirty machine. Poor storage and sourcing habits are common mistakes that can make your coffee milky and bad-tasting.

Read on to learn more about what causes these issues and how you can fix them. With the proper equipment, ingredients, and brewing methods, there is no reason you should end up with cloudy, bitter coffee.

Key Take Aways

Keep your Chemex clean, use good water and coffee beans, store your beans in air-tight containers, and don’t over-extract your brew. This will make for a consistently excellent coffee and coffee experience.

1. Unfiltered Water With Minerals

Using hard water is one of the most common brewing mistakes beginners make. It’s important to remember that your coffee is mostly water. The type of water you’re using greatly impacts whether your Chemex coffee looks cloudy or tastes bad.

Soft water is the best way to brew coffee. Ideally, you want odorless, colorless water with no chlorine and a pH of 7. That’s difficult to find in most areas. Minerals in your water can include substances like calcium and magnesium. Such water is called hard water.

Hard water not only alters the flavor of your coffee but also results in limescale buildup and reduces the life of your coffee water. Bottled water and tap can contain varying concentrations of minerals. Higher levels might lead to less savory coffee. So the best solution for clean water is to filter your water, whether you are using tap or bottled.

unfiltered tap water produces cloudy coffee
Cloudy water often comes from water stored too long in dirty coffee machine reservoirs

There are many options, including charcoal filters or reverse osmosis water. If your Chemex coffee is turning milky, the first step is to get your tap water tested. Once you know for sure whether you’re dealing with hard water, you can take steps to treat it.

For hard water over 400 TDS, you may consider using a Brita water filter pitcher (or similar) to clear out excessive amounts of minerals.

What Is TDS?

TDS is “Total Dissolved Solids.” It measures the amount (concentration) of dissolved substances found in drinking water. Minerals include sodium, zinc, magnesium, iron, potassium, calcium, and bicarbonate. The lower the TDS level, the better water is for drinking.

Total Dissolved Solis (milligrams per liter)Tasters Rating
Less than 300Excellent
300-600Good
900-1200Fair
Over 1200Unacceptable
TDS, Total Dissolved Substances

Don’t lose sleep over TDS, though. Most tap water is between 170-400 TDS and tastes good enough.

Additionally, if the water you’re using is boiling, you will end up with bitter and burnt coffee. For pour-over methods, the ideal temperature is between 195F and 205F. So pay close attention to your water temp and get the most out of your Chemex coffee maker.

2. Issues With The Coffee Grounds

high quality coffee beans reduce cloudy coffee brews

Picking the right coffee grounds is the most important step in brewing. After all, there’s a lot that can go wrong.

The most common mistake is buying ground coffee. When you buy pre-ground coffee instead of whole beans, you cannot guarantee the quality of your grind. Whole beans retain their flavor and texture 10 to 14 days after they’ve been roasted, while ground coffee becomes stale within a day.

Buying freshly roasted whole beans is equally important. If you’re sourcing your coffee from a subpar company or unreliable retailer, there’s no telling how old they are. Beans past their roasting date or badly roasted beans will make your Chemex coffee cloudy and unsavory. 

A huge reason your coffee looks milky and tastes bitter is that your grind is the wrong size. For properly brewed, delicious pour-over coffee, you need a medium-coarse grind. Fine grinds are reserved for espressos and other types of coffee.

If you try to use a fine grind in your Chemex coffee, you’ll end up with an over-extracted, bitter brew. 

3. Dirty Machines

A clean Chemex keeps brewed coffee from being cloudy
A clean Chemex is essential to producing coffee without cloudiness

A common mistake many home brewers make is simply not washing their coffee makers. Properly washing a Chemex machine can be difficult, but the alternative is bacteria buildup! 

Over time the oily residue, leftover coffee grains, and mineral deposits collect inside the coffee maker. If you don’t give it a thorough clean every few months, you’ll end up with cloudy coffee!

The trickiest part of owning a Chemex is trying to scrub the insides of the conical beaker design. Your best bet is to use regular dish soap, an old rag, and warm water. If you’re willing to put in the extra effort and remove the handle, you can use a dishwasher. All you need to do is untie the leather cord, and the handle will come right off.

Chemex sells its custom cleaning solution and brush designed to scrub the insides of its coffee maker. But if you don’t want to spend money on cleaning supplies, you can always use a simple vinegar cleaning solution. Use equal parts distilled white vinegar and warm water, let it soak, and then wash it out properly.

You also need to wash your paper filters. Dirty flavors collect particles or leftovers from previous brews that will give your coffee a milky appearance. If you’re brewing a light roast, you may even notice a papery aftertaste that ruins the flavor of your coffee. 

Before you brew a fresh batch, put your filter in the dripper and run hot water through it. This cleans it and ensures you’ll get a clean, fresh-tasting brew.

4. Poor Storage

store coffee beans properly to keep coffee from brewing cloudy
Use air-tight containers to store coffee and keep it fresh.

If your coffee is old and past its ideal date, it won’t matter how great your coffee maker is. For the perfect cup of pour-over, you’ll want to finish your bag of coffee beans within 7 days. 

You can ask your local baristas for smaller bags of ground coffee. But never purchase your favorite beans in bulk. They will go bad!

In addition to buying only a week’s supply of coffee at a time, you also need to devise a good system for storage. The ideal way to store your coffee is in an air-tight container on a shelf in your kitchen.

That’s right! Coffee beans are meant to be kept at room temperature, not in a fridge or freezer. While freezing may extend its life, the moisture and condensation can ruin the beans’ flavor and aroma. You’ll end up with a watery and cloudy brew that only holds hints of the ground’s original taste.

Similarly, keeping your coffee in the freezer will allow moisture to seep in. Soggy beans make for terrible coffee. It’s even worse if you’re exposing ground coffee to condensation.

5. Over Extraction

Over extracting a chemex while brewing can create coffee cloudy

Multiple brewing mistakes can lead to over-extracted coffee. The first is if you’re simply brewing the grounds too long. Doing too much can ruin the delicious flavor of your coffee. The coarser the grind, the longer you’ll need to brew it

Once the grounds are past the ideal grinding stage, they will start releasing chemicals that will affect your brew’s texture, flavor, and appearance. With the medium-grind ideal for the Chemex, you shouldn’t need to brew your coffee for too long.

Then, there’s over-agitation. You stir, shake, or swirl the mixture for too long. While we completely understand that brewing coffee is often a therapeutic process, you need to take care not to be too rough in your brewing.

The third reason for over-extraction is using too much water. Carefully measure out your coffee and water. You can’t eyeball ingredients if you’re trying to get the perfect cup of pour-over coffee. When you go past the target water quantity, the extra water pulls out the chemical flavor from the beans.

Finally, you need to remove the filter. Let it sit for too long, and your coffee will have a cloudy texture. Plus, the over-extracted water will start seeping in and ruin the brew’s flavor.

If you’re making any of the following missteps, you may get cloudy, bitter, or dull coffee.

Sources and Citations

What’s In your water: Total dissolved solids (TDS) in drinking water. Quench Water. (2022, February 10). Retrieved September 6, 2022, from https://quenchwater.com/blog/tds-in-drinking-water/

Christopher Mize
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