A dishwasher appliance and method of operation is provided. The dishwasher appliance may include a tub defining a wash chamber, a coarse filter disposed, a recirculation pump, and a drain pump. The method may include activating the recirculation pump to flow wash fluid through the coarse filter in a primary flow direction, and activating the drain pump to flow wash fluid through the coarse filter in the primary flow direction for an initial purge cycle. Further included may be flushing wash fluid through the coarse filter and into the tub in a secondary flow direction opposite from the primary flow direction. Still further included may be activating the recirculation pump to flow wash fluid through the coarse filter in the primary flow direction, and activating the drain pump to flow wash fluid through the coarse filter in the primary flow direction for an additional purge cycle.