A written hand washing procedure approved by the office shall be posted at each sink used for washing hands. Hands shall be washed according to the posted approved procedure by the provider, each staff member, each volunteer, each substitute, and each child in care at least: After toileting or diapering; Before food preparation or eating; and After an outdoor activity or handling an animal. Diapering shall be performed in accordance with a written diapering procedure approved by the office.