CCTV plays an essential role in keeping sewer pipe performance at a desirable level. A sewer pipe condition score is normally assigned to each sewer pipe based on the type, quantity, and extent of defects observed through CCTV inspections. While the impact of different factors on the condition score has been considered in several studies, the impact of these factors on the underlying defects has not been investigated. The aim of this study was to investigate the effect of various factors, including age, material, diameter, and groundwater level, on the prevalence of eight defect categories in the transmission sewer network of Auckland, New Zealand.