title_body: How many times can I reuse coffe-grounds to make myself a coffee until it is tasteless/useless?
upvoted_answer: Zero.
  
  when you make coffee, (ideally) all of the desireable solubles get extracted, what remains are, if done well, most of the undesireable ones and insoluble components. A second round of extraction will not produce anything you'll want to drink, unless you like bitter brown water.