title_body: Reusing paper filter by placing metallic net filter in it
upvoted_answer: Brewed coffee ages like milk.  As soon as it is brewed its flavor begins to degrade and deteriorate, which is why it always tastes much better freshly brewed.  While you may not necessarily taste the difference from one pot to the next, it has definitely changed your overall expectation of the flavor.  The bouquet of coffee also is very complex, as is obvious from the fact that there is a distinct change in the scent from the time you grind to the time the brewing stops.
  
  One flavor issue with reusing paper filters is that they tend to stop a large amount of the oils in the coffee from making it into the final product.  This could be desirable, as many (myself included) prefer the taste of paper-filtered coffee that does not contain the compounds found in the crema (the thin layer of foam on top of espresso, Turkish or French-press coffee).  These, which are often a combination of both sweet and bitter, are trapped by paper filters, but they will break down in the paper over multiple uses and wash into your coffee anyway, but not necessarily in the same form, which further changes the flavor profile.
  
  If waste is a major concern, but you prefer paper-filtered coffee, you can make a compromise and use an Aeropress.  These use filters that are only about 2 inches in total diameter, meaning less gets tossed with each brew.  You could also look into filters made with recycled paper.  It won't reduce the waste, but it will reduce the environmental impact somewhat.
  
  Remember, though, that in the end paper filters are biodegradable and, if thrown away along with the grounds, can actually aid in creation of compost -- a good thing.