Proper hand washing practices in food service establishments are important for the adequate reduction of microorganisms on hands. To address practical barriers associated with active and direct interventions, this study employed passive and indirect interventions to examine whether the simple use of a water flow timer and an informational poster could influence food handler hand washing practices. A within-group, multiple-intervention experiment including baseline, single intervention, multiple intervention, and withdrawal phases was conducted at a student-operated, full-service restaurant over 4 weeks. We recorded a total of 839 hand washing practices over 112 hr of observation using a motion-detecting camera. Findings showed that the presence of a water flow timer increased the duration of hand washing and the compliance rate to proper scrubbing duration. The effects were robust in the weeks when establishments were busy with high-customer volume. The findings provide useful data regarding the use of passive and indirect interventions to change food handler hand washing practices.