A microbiological test array with a generally flat base having a plurality of upwardly projecting microwells connected by a microchannel to an open reservoir formed in a top surface generally parallel to the base of the test array. The reservoir has an opening to permit an inoculum-broth liquid solution to flow from the reservoir through the microchannel, to a sacrificial evaporation well having an air vent port adapted to control a vacuum filling process, and subsequently to be distributed into each of the plurality of microwells.