Leak Detection in South Auckland

South Auckland was farmland until the Southern Motorway pushed through in the 1950s, and most of what is under its streets went in over the next thirty years. Ōtara's state housing started in 1958 and had 3,000 houses within a decade, central Māngere followed in 1962, Papakura, Manurewa and Takanini had grown into one built-up area by 1964, and Manukau's new city centre opened its mall in 1976. That is a lot of galvanised and asbestos-cement pipe wearing out together.

The ground changes quickly. Māngere, Wiri and Puhinui sit on the lava and scoria of the Auckland volcanic field, the Takanini and Papakura flats are drained peat and soft Tauranga Group clays with groundwater a metre down, and the harbour edge at Weymouth, Clendon and Conifer Grove is estuary margin. Each hides a leak differently, so we never assume the wet patch marks the pipe.

The work splits three ways. In the state-housing belt it is failed laterals, shared supplies on cross-leases and new townhouses tying into old mains. In Wiri, Manukau and the Māngere industrial blocks it is private networks under hardstand that no public plan covers. In Takanini, Drury and Ōpaheke it is greenfield subdivision, with up to 22,000 homes planned around Drury alone, where as-builts seldom match the ground. Watercare supplies all of it from the Hūnua dams and the Waikato, Vector carries the power to Papakura and Counties Energy beyond, and our Waiau Pa yard is 25 to 40 minutes away.

Three pipe generations sit side by side across South Auckland. The 1950s and 60s state houses in Ōtara, Māngere and Papakura got galvanised steel laterals off cast iron and asbestos-cement mains; the galvanised pipe is rusting through and pinholing under driveways, and the AC mains crack at the joints. Manurewa, Weymouth and Clendon's 1970s and 80s streets are the asbestos-cement and copper generation, with Dux Quest polybutylene inside the later houses.

Takanini, Drury and the Manukau rebuilds since 2000 are MDPE and PE100 with tracer wire, except that fast subdivision leaves as-builts that do not match the trench and landscapers break the fittings. The 1990s laterals in between, PVC and early alkathene with no tracer wire, are invisible to an electromagnetic locator. So the common South Auckland job is a section with a 1960s galvanised line into a 2010s townhouse, where we first find out what is actually there with GPR and a sonde.