Weekly microbial time-series sampling was conducted at two coastal sites in Sydney, Australia based on their exposure to high (Foreshore Beach) and low (Maroubra Beach) stormwater and sewage pollution. Foreshore Beach, within Botany Bay is frequently exposed to stormwater input, as well as periodic sewage overflows released from upstream overflow outlets and discharged into Botany Bay. Maroubra Beach is east facing, exposed to the Tasman Sea, where water quality is less impacted by stormwater input.