A chiller bath includes a tank for holding a volume of chiller water; a dosing system for dosing a first solution and a second solution into the chiller water, arranged to create a plurality of zones within the volume of water, wherein each zone has a higher concentration of either the first or the second solution than surrounding portions of the volume of water; and a meat or poultry immersion arrangement for immersing and moving carcasses in the chiller water. A method for reducing bacterial load on meat or poultry includes generating a plurality of zones within a chiller bath containing water by dosing a source of alkalinity and antimicrobial into the water, wherein the plurality of zones comprises at least one alkaline zone with a pH above 8.5, and at least one antimicrobial zone with pH below 8.5; and submersing meat or poultry in the bath. The zones can also be generated using spray nozzles in a meat or poultry operation.