Leak Detection in Mercer

Mercer is a small rural settlement on the Waikato River, alongside State Highway 1 and the Waikato Expressway. It is better known as a stop on the road between Auckland and Hamilton than as a town in its own right, with a handful of commercial premises and a scattering of houses, farms and lifestyle blocks.

Most properties around Mercer are rural, running on bores, river takes or tank supply with private pipework that may be decades old. Low-lying land near the river is prone to high groundwater, which makes trenches wet and can mask where a leak is actually coming from.

Reticulated services where they exist are managed by Waikato District Council. Because the settlement is small, we are usually called out for farm and lifestyle block work, roadside service locates and repairs on long rural water lines rather than town mains.

With 51 dwellings there is not much town pipe in Mercer, and what there is dates from the railway era: galvanised laterals and short old mains serving the cottages and the roadside businesses. Nearly all the water pipe around Mercer is private and rural, alkathene from bores and river takes, laid across peat and clay flats and hills over fifty years, joined and patched by successive owners, with no tracer wire and no plan.

The peat is the problem. Drained peat on the flats keeps subsiding, and the regional council's own catchment notes describe ongoing peat subsidence and land-level lowering from drainage. A rigid pipe laid level thirty years ago is now hanging between high spots, pulling joints and fittings apart, so the leaks we find here are at joiners and tees rather than pinholes. Replacement in MDPE, which bends with the ground, is usually the right fix rather than another patch.