title_body: Best practices for reheating coffee
upvoted_answer: Cold-brewed coffee heats well. Hot-brewed coffee that is old (whether on the warmer for hours or allowed to cool) will have pronounced flavors that most drinkers find unpleasant.
  
  If you are concerned about wasting grounds, either brew smaller batches of hot-brewed coffee, or look into cold-brewed coffee. Most groceries carry pre-made cold brew or cold brew concentrate (read the labels to see if added water or milk is recommended), or consider getting a brewing container to make at home in the fridge. It stays good for 7-10 days once brewed so you can purchase or make a week's worth at a time.