How To Clean Your Coffee Maker - The New York Times

The protocol may vary slightly for different makers and models, but for any coffee maker, the goals are the same:

• Keep bacteria and mold from setting up residence, particularly in the water reservoir. A 2011 report (PDF) found that the water reservoir is the fifth germiest spot in the kitchen or bathroom—even more so than the bathroom faucet handle.
• Get rid of oil residue that can make a hot brew taste stale.
• Eliminate any mineral buildup, which can block water flow and elongate the brewing time, potentially turning hot coffee tepid or affecting the flavor of your coffee.

Immediately after each use

Take the used filter and grounds out of the brew basket and discard them. Rinse out the brew basket and the carafe (once it’s empty). Open the lid on the water reservoir, so it can air dry.

Wipe down the body of the machine, cleaning away any splatter that may have occurred over the course of the day.

Once a week

Photo: Sarah KobosBe sure to dry the parts of your coffee maker thoroughly before replacing them. Photo: Sarah Kobos

Take apart the detachable components and wash them well with warm water and mild dish soap. Pay attention to the corners and grooves, where bacteria and mold can hide, and where coffee oils and grounds accumulate. Rinse away the suds and place the components on your dish rack to air-dry. If you happen to be running the dishwasher, place the dishwasher-safe components in the dishwasher; these pieces typically include the basket, coffee scoop, and glass (not thermal) carafes, but check your manual to make sure.

A thermal carafe needs to be hand-washed with warm water and dish soap, since the dishwasher can damage the double-walled vacuum insulation. A bottle brush can be handy for reaching those deep, dark recesses where residue and germs like to hide, and might be necessary if the opening of the carafe is too narrow to stick a hand through.

Every two or three months (or when the indicator lights up)

Over time, mineral deposits build up in your brewer—more so if you live in an area with hard water. You can reduce this by brewing with filtered water, but even then you should descale (or demineralize) your machine a few times per year. Different coffee makers come with different recommendations for how and how often to descale them, so consult your manual. Beyond that, it’s also good practice to “descale whenever you notice that the coffee maker takes too long to brew or leaves water in the tank,” said Claire Ashley, coffee and tea category director at OXO (maker of our top pick, the OXO Brew 9 Cup Coffee Maker).

Some models feature an indicator light that reminds you it’s time to descale. Just be aware that these machines don’t in fact sense minerals in your machine—they simply track how many brew cycles you’ve run and turn on the indicator after a certain number of brews. (For our OXO pick, it takes 90 cycles, so that’s once every three months, if you brew once a day.) The machine shouldn’t stop working while the indicator is on. To reset it, simply run the machine’s descale cycle.

When it’s time to descale, you can use this DIY method, which our kitchen team uses:

Fill the water chamber with one part water, one part white vinegar. Run a cycle, empty the pot, and do another vinegar cycle. “Vinegar not only breaks down mineral deposits, it’s also able to remove bacteria at safe levels,” said Jason Marshall, ScD, lab director at the University of Massachusetts Lowell’s Toxics Use Reduction Institute (TURI), who has tested cleaning products for various brands.

Then empty the pot again and finish off with tap water. Repeat a few times until the vinegar scent has dissipated.

To avoid second-guessing yourself as to whether you’ve truly gotten rid of every trace of vinegar, you can run the brew cycle with a descaling solution instead, which is what OXO suggests in this video.

To clean a stained thermal carafe

Stainless steel thermal carafes can also pick up tough coffee stains over time. To break down these stains, dissolve a bottle-cleaning tablet in the container and let it sit for as long as the instructions advise—or overnight, if you’re dealing with really stubborn stains.

Using denture tablets to do the same thing is a popular internet hack, and those do tend to have the same active ingredients, citric acid and baking soda, as bottle-cleaning tablets. But be forewarned—denture tablets might also contain flavor and color ingredients that could compromise your container or your coffee.