This tall sewer vent dominates the skyline at West Botany Street in the southern suburb of Arncliffe. It was constructed at the turn of the 20th century as part of the Western Outfall Sewer. By the late 1800s, the five outfall sewers which drained into Sydney Harbour had grossly polluted it. As replacements, the Southern Outfall Sewer was constructed in 1886 including an experimental sewage farm, followed by the Bondi Ocean Outfall Sewer in 1889 and the Western Suburbs Outfall Sewer in 1898. These outfalls still serve the city today, south of the harbour. Sewer vents introduce a flow of fresh air through sewers to reduce the production of noxious and corrosive gases by enabling their release.