I drink coffee but not black. However I knew 2 army sergeants who lived off the darkest strongest coffee I've ever seen.
During one field exercise they actually drank half the pot, filled it back to the top with water and poured the already made coffee into the back of the machine to run it through MORE coffee grounds!
On another field exercise we forgot the coffee maker but had coffee grounds. The boilers in one of the buildings heated the water enough to make the coffee if we could find a way to pour it through the grounds... The top of a Gatorade bottle was cut off flipped over in the lower piece and behold our peculator was ready