A few tips for dealing with bitter coffee taste and other injustices served up by your drip coffee maker.
Drip coffee makers are great for convenience, but if you shop for coffee makers long enough you’ll find that pretty much all makes and models have been reviewed by customers who have been affected by at least one of the problems discussed here. In all honesty, a “perfect” drip coffee maker probably doesn’t exist. Between mechanical quirks and human error, there’s an awful lot that can go wrong, with the result being bitter coffee or worse. If you’re a “coffee aficionado” (I kind of hate that term!) then maybe you should be using a French press or Chemex. However, if you’re like most people, you just want to find a solution with the equipment you already own.
Bitter coffee, weak coffee, and sour coffee. Gross!
There are a lot of variables that affect the taste of coffee. If your coffee maker is producing bitter coffee or an otherwise undesirable cup, and if you’ve been using the machine for a while, the first thing you should do is give it a good cleaning. Check your owner’s manual for recommended cleaning methods. If you don’t have easy access to the manual or are just too lazy to read it, run a 50/50 (or less) diluted vinegar/water mix through your coffee maker. You could also check out this handy step-by-step cleaning guide by a former coffee shop boss, and I have also written a whole thing about how to clean a coffee maker. Some coffee makers, such as the high-end Brazen Plus, specifically say NOT to use vinegar, so digging up that owner’s manual might be a good idea after all. If you’re mechanically inclined and your coffee machine is out of warranty, you could open up the machine and find a hose to inspect. If the hose contains any buildup, then you may have found the cause. Yucky buildup can not only be the cause of bitter coffee, but it can also lead to water flow problems. Thanks to Baristador’s Steve Davis for the tips in his article on why your cup of coffee tastes bitter.
If cleaning with vinegar or other methods isn’t working (or not an option), you can also try using a descaling powder such as Urnex Dezcal. High end coffee makers such as Brazen and Bonavita (read review here) recommend this.
Aside from cleaning and checking hoses, you should also consider the method by which you’re preparing the coffee machine to brew. Here are a few possible culprits that can lead to bitter coffee taste:
Beans that have been over-roasted can result in bitter coffee or a burnt flavor. It would also be worth checking on the freshness of your beans and how long ago they were roasted. If you’re buying pre-ground coffee, you should try to find out how long ago the coffee was ground. Coffee that was bought “fresh” yesterday may have been ground a long time ago, so it might be worth asking some questions or finding a new coffee source.
Not enough coffee grounds can lead to overextraction, pulling unwanted compounds out of the beans and into your coffee pot. The result? Bitter coffee.
Coffee that is too finely ground can also lead to overextraction, making bitter coffee that will cause you to frown.
Coffee that is too coarsely ground can result in underextraction from water passing through too quickly and not having enough contact time with the grounds.
Scooping too much or too little coffee into the machine could also result in the wrong extraction, depending on how much water is being used.
Quality of water is a big factor. Some coffee makers, such as the Mr. Coffee BVMC-SJX33GT (read review here) and Cuisinart DCC-1200 (read review here) come with built-in water filters (which need to be changed periodically). If your coffee maker doesn’t have a built-in water filter, try making a pot with bottled water and see if that makes a difference.
Water temperature is a huge factor that is not to be overlooked. If your coffee tastes sour or weak, you may not be brewing the coffee at a hot enough temperature. With a drip coffee maker, you’re somewhat at the mercy of the machine itself, but you can always preheat the water by running it through the machine without any coffee first. Once you have your pot of hot water, just pour it back into the coffee maker with coffee in the basket and make a pot. It should be much hotter this time around.
Water temperature that’s too high can also make for bitter coffee. If your drip coffee maker lacks a temperature control (and most do), make sure you’re pouring cold water into the machine.
Sometimes even paper filters can result in bitter coffee or something else that’s less than ideal. If you’ve been using paper filters and nothing else, consider switching to a gold tone permanent filter.
A lot of coffee drinkers complain about “plastic taste” in coffee, typically from a newly purchased coffee maker. Not too long ago I wrote about seven ways to get rid of plastic taste, and here are two of the most common solutions:
Wipe down the insides of your coffee maker with some kind of alcohol, whether it’s cheap vodka or plain old rubbing alcohol. A lot of plastic-taste victims have said that this method worked for them, presumably because the alcohol washes away residue on the plastic parts of the coffee maker that seep into the water. Just soak a paper towel with alcohol and wipe down any part of your coffee machine that comes into contact with water.
Run some diluted white vinegar through your machine (without the coffee grounds, of course). A 50/50 mix of water and vinegar is often advised, but a weaker dilution can work as well. The more vinegar you use, of course, the more water you’ll have to run through the machine to rinse out the vinegar taste and smell.
If these methods don’t work for you, check out all seven ways of dealing with plastic taste.
Coffee Maker Overflowing
This is a curse that far too many owners of drip coffee makers face. Sometimes the machine is at fault, but just as often it’s the person making the coffee who needs to make an adjustment.
When coffee overflows out of the top of a coffee maker, it’s generally because one of two things is happening:
- Water is entering the brew basket too quickly, or
- Water isn’t getting through the coffee grounds and filter fast enough
These causes may sound like exactly the same thing, but they point to different problems. If water is entering the brew basket too quickly, it could be due to the water being too soft. If you own a Bunn Velocity Brew (read review here) that’s overflowing, you can request a free “flow restrictor” sprayhead that might solve the problem. They might also offer this for other models as well. If you own a different make of coffee machine, contact the manufacturer’s customer service center to see if they have a similar option.
Something else you could try would be to use water that hasn’t gone through your water softener, such as bottled water. You might not want to use bottled water all the time due to the cost, but it’s a way of ruling out water quality as a potential cause of overflow.
Overflowing could also be due to a water nozzle or sprayhead not being attached properly. Take a look inside your machine to see if anything needs to be snapped back into place.
If everything is in order, then it would be fair to assume that water isn’t exiting the basket fast enough.
Using two paper filters by accident could easily be the cause, and so could using a paper filter inside a permanent gold tone filter basket.
Another possible cause of overflow would be the grind being too fine. Cone-shaped filters should use a medium-fine grind, and medium grind is usually right for both flat-bottomed “cupcake” style filters and gold tone permanent filter baskets.
The quantity of coffee grounds is another issue that is easily remedied. Some coffee machine owners scoop so much coffee into their machines that there’s hardly any room for the water once it starts flowing. Try brewing half a pot to see if the overflow continues. If it stops, then you may just need to adjust the fineness of the grind, quantity of coffee, or both.
Owners of coffee makers that have a thermal carafe should also look at their carafe lid and placement of the carafe itself when brewing. This type of overflow isn’t really overflow; it’s just coffee not making it into the carafe (you can tell the difference by the absence of coffee grounds in the spillover). The Cuisinart DTC-975BKN (read review here), for example, is notorious for overflowing, but many owners of that coffee maker have figured out their own solutions to the problem.
A final bit of advice: Ask for help!
Even the most hardcore coffee drinkers who roast and grind their own beans could fall prey to any one of these issues leading to bitter coffee, overflow, or plastic taste. Your local coffee retailer can’t do anything about plastic taste (couldn’t hurt to ask for suggestions!), but it is most certainly worth asking for a coffee recommendation based on the machine you have. The person who sells you your coffee will need to know the filter type (cone, flat-bottom, or permanent) and may also be interested in your brand of machine. Discussing the problem specifically (bitter taste, overflow, etc.) is obviously worth doing. You might need to try a few different roasts and grind sizes to get it right. Keep notes on what works and what doesn’t. Barring mechanical defects, most victims of these issues should be able to resolve taste and overflow issues through trial and error.