For large percolators, follow the manufacturer’s directions. For large coffee urns, measure out:

Put the ground coffee in a jelly bag, nut milk bag, or cotton pillowcase large enough to allow for double expansion and securely tie it off. Bring the water to a low boil and take it off the heat. When the water has cooled to 200° to 205°F, pour into the coffee urn. Place the coffee-filled bag in it. Let stand, covered, for 5 minutes. Agitate the bag several times during this period. Remove the bag, cover the urn, and serve at once.