No bleach or harsh chemicals required.
Coffee makers are great tools to help you brew coffee at home. However, they are also are literal hotbeds of bacteria and yeast, which means that it's important to be diligent about cleaning them. Luckily, it’s an easy process to clean your drip machine and you don’t need anything other than water and vinegar (apple cider vinegar or distilled white vinegar). And here's how it's done:
To start the cleaning session, take out and wash all removable parts of your drip coffee machine with warm soapy water and rinse thoroughly.
Dry the removable parts (air dry or towel dry) and then wipe down the coffee machine.
Pour equal parts apple cider vinegar or distilled white vinegar and water into your drip coffee maker.
Tip: you can measure how much you are using in your coffee carafe.
Start the brew cycle as you normally would when making coffee in a coffee maker. Let the water and vinegar solution go through the brew cycle and turn off your coffee maker once done.
Toss the solution (which may have snagged calcium buildup, oily residue, as well as bacteria and yeast).
Run clean water through your brewer at least twice to remove any vinegar residue. This will also serendipitously clean out your carafe.
And you're done! It’s not necessary to do this, every time you brew fresh coffee grounds; once a month is perfectly ideal.