Sewage treatment and disposal

A brief history of sewage treatment and disposal in Invercargill and Bluff.


1910 – 1958: Foul sewerage reticulation was first laid in Invercargill in 1910, with the main outfall offshore at Janet Street. Effluent was treated in a large septic tank then discharged through a wooden drain leading into the New River Invercargill Estuary. Treatment was later improved by the construction of a second parallel tank. At a later date the wooden drain was replaced with a cast-iron outfall pipe discharging effluent to the New River Estuary main tidal channel.

1959 – 1969: By 1959 the rapid growth in Invercargill’s population meant the reticulation system and treatment process could no longer cope with the volume and type of effluent being produced. The City Council at the time drew up a loan programme to finance development and extensions that would include new intercepting and trunk sewers, new pumping stations, and a new primary treatment plant at Clifton. Work started in November 1966, and the new Clifton Wastewater Treatment Plant was opened on March 13, 1969.

1970 – present: In 1992 a major upgrade of the Clifton Plant began. This upgrade involved installation of a secondary treatment facility and upgrading of the old equipment. This work was completed in 1992 and provided improved facilities for the treatment of both residential and industrial waste. A further upgrade to Tertiary Treatment was completed in 2004. This comprised of facultative ponds and wetlands to further improve effluent quality by reducing bacteria numbers. The upgraded plant has a consent to discharge treated wastewater for 25 years.

The following links are to videos describing the treatment process at the Clifton plant:


Bluff sewage treatment and disposal

Pre 1960s: Until the mid 1960s Bluff’s sewage was collected in nightsoil buckets. Due to the inherent health risks of the system, the Department of Health insisted that Bluff install a sewage system.

1965 – 1990: By 1971 all Bluff households were connected to a piped system, which collected sewage at a pumping station on the Harbour Foreshore. From there it was pumped over the hill and discharged untreated into Foveaux Strait, just south of Ocean Beach.

1990 – present: By the 1990s the discharge of untreated sewage to the coastal environment was no longer acceptable, and the Council began investigating treatment systems. A new plant was completed in December 2000 with a consent to discharge treated wastewater for 25 years. As part of the consent the Council had to ensure that the wastewater caused minimal impact on the environment, and the health of the people in the area.