Leak Detection on the North Shore

The North Shore was holiday country until the Harbour Bridge opened in 1959. Devonport and Takapuna were the exceptions, settled around the naval base and Lake Pupuke with Victorian and Edwardian villas and 1920s bungalows. The bridge changed everything else: Glenfield's population went from 5,683 to 13,335 between 1961 and 1966, the East Coast Bays doubled to 12,000 by 1966 and became a city in 1975, and holiday homes in the bays gave way to permanent houses. Albany took the 1990s, and Long Bay and Northcote carry the current build, where Kāinga Ora has been replacing 298 state houses with 479 new ones since 2016.

Underground that reads as four generations of pipe. Under Devonport and Takapuna we find galvanised and lead-era laterals through basalt from the Mount Victoria and Pupuke lava flows. Under Glenfield, Birkdale, Northcote and the bays it is asbestos-cement mains with copper and galvanised laterals from the 1960s. Albany and Unsworth Heights carry polybutylene and early plastic; Long Bay and the Northcote rebuild are PE with tracer wire.

The ground is East Coast Bays Formation sandstone and mudstone from Devonport to Long Bay, weathered to a clay that saturates in winter and slides on cliff-top and gully-head sections. Watercare runs the water and the Rosedale plant, Vector owns the lines and the gas, and Chorus built the fibre. We come over the bridge from Waiau Pa for jobs that justify the hour and group the rest.

The pre-1940 streets of Devonport, Takapuna, Milford and Birkenhead still run galvanised laterals, the oldest off lead-jointed cast iron, through basalt and scoria near the cones and clay elsewhere, so the leak is usually a corroded pinhole and the lateral too far gone to patch. The 1960s subdivisions of Glenfield, Birkdale, Beach Haven, Northcote and the East Coast Bays got asbestos-cement mains with copper or galvanised laterals; the AC cracks at joints under driveways and roots, and the long laterals to houses below street level are where the loss hides.

Albany, Unsworth Heights and 1990s Greenhithe fall in the Dux Quest polybutylene window, so failed fittings inside and untraced alkathene outside are the pattern. Long Bay, the Northcote rebuild and the new apartment blocks in Takapuna and Albany are PE100 and PVC with tracer wire, where the usual fault is a service crushed during landscaping. Metallic pipe we trace directly; plastic without a tracer needs a sonde, an induced signal or a pothole, and on the Shore that covers most of the 1980s and 90s stock.