Boiling causes bitterness, so never boil coffee. It should be brewed between 195 and 205 degrees Fahrenheit.
Don't reheat coffee. Make it fresh each time you serve it, and make only as much as you plan to drink. Coffee holds its flavor best at 185 degrees Fahrenheit.
Use freshly drawn cold tap water. Water is 98 percent of every cup; consider using a water filter or bottled water if your water tastes peculiar.
Don't reuse grounds. What remains are the unpleasant bitter components of the coffee.
Use the correct grind for your coffeemaker. Too fine a grind will cause over extraction and bitterness, or clog your brewer. Too coarse a grind will cause watery coffee. For drip brewers, the appropriate grind should allow the coffee to finish dripping in two to four minutes.
We recommend using two rounded tablespoons of ground coffee (one standard coffee measure) for each six fluid ounces of water. Keep those proportions consistent, regardless of the quantity you make. You can adjust proportions to taste, but remember that skimping (i.e. grinding finer and using less coffee) makes for a thin, bitter brew.
Coffee can be kept warm over a burner for only about 20 minutes before the flavor becomes unpleasant. An airpot or vacuum server will keep coffee hot and delicious for much longer periods of time.
