The Pasteurized Milk Ordinance (PMO) allows for milk tanker trucks to be used repeatedly for 24 h before mandatory clean-in-place (CIP) cleaning. There are no specifications for length of time a tanker can be empty between loads. We partnered with a Pacific Northwest dairy company to investigate if extended idle time between loads influences microbiological populations in subsequent loads of milk. This processor does not allow tanker trucks to sit idle between loads for more than 6 h. Two farms were selected to participate in the study based historical microbiological data from January 2014 through December 2015, quantified using Foss Bactoscan and reported as individual bacteria count (IBC) and preliminary incubation count (PIC). Historically, Farm A IBC and PIC (n = 729) averaged 47.8 and 432.3, and Farm B (n = 982) had substantially lower average IBC and PIC (8.8 and 13.2). The study occurred over 6 consecutive days; for 3 d Farm B milk was collected immediately after unloading farm A, and the other 3 d Farm B milk was collected 6 h after unloading. For each day milk samples were obtained each farm bulk tank and from the tanker before unloading. Each sample was microbiologically assessed in duplicate for standard plate count (SPC), lactic acid bacteria (LAB), coliforms. Colony isolates were assessed for lipolytic and proteolytic activity using spirit blue agar (SBA) and skim milk agar (SMA), respectively. There was not a significant difference in microbiological counts and enzyme activity in farm B’s tanker sample where comparing 0 and 6 h between hauling. We have demonstrated that 6 h between loads does not negatively impact subsequent loads of milk, and that the processors parameters are adequate.