A dishwasher appliance includes a tub that defines a wash chamber for receipt of articles for washing. The dishwasher appliance also includes a lower spray assembly located in the wash chamber and configured to direct a spray of fluid into the wash chamber. The dishwasher appliance further includes an upper spray assembly located in the wash chamber above the lower spray assembly along the vertical direction. The upper spray assembly is configured to direct a spray of fluid into the wash chamber. A sump is positioned at a bottom of the wash chamber for receiving fluid from the wash chamber. The dishwasher appliance further includes a pump in fluid communication with the sump. The pump is configured to draw fluid from the sump. A main conduit extends between the pump and the upper spray assembly. The main conduit includes an upper end and a hole defined in the upper end.