Drilling a water bore in Hawke's Bay

The main aquifer systems

The Heretaunga Plains, around Hastings and Napier, is a layered sequence of river gravels and finer sediments recharged largely from the Ngaruroro and Tutaekuri rivers. Parts of it are strongly confined, and artesian conditions are well known in the lower plains. Yields there can be very high, which is why the area supports so much horticulture.

The Ruataniwha basin in Central Hawke's Bay is a separate system with its own gravel and sand layers, generally less productive and more variable than the Heretaunga. Away from these two basins, in the hill country and coastal margins, the geology is dominated by older sediments and mudstones where bore yields are typically low and much harder to predict.

Typical depths and what to expect

Depth depends entirely on which layer you are targeting. On the Heretaunga Plains a productive confined gravel may sit well below the shallow unconfined water, and drilling to the shallow layer to save money can leave you with a bore that is unreliable or of poorer quality. In the hill country, a hole that produces enough for stock may take several attempts, and a dry or very low-yield hole is a genuine risk. Nearby bore records are the only sound basis for a depth estimate.

Water quality and artesian conditions

Confined and artesian bores need careful construction: correct casing and a proper surface seal are what stop cross-contamination between layers and protect the aquifer. Hawke's Bay has strong reasons to take this seriously, and construction standards are enforced accordingly. Iron, manganese, and hardness show up in some parts of the plains, so a water quality test on the finished bore is worth budgeting for.

Consents in Hawke's Bay

Hawke's Bay Regional Council manages bore construction and groundwater takes through the regional resource management plan. Bore drilling generally requires notification and must meet construction standards, modest stock and domestic takes may be permitted subject to conditions, and larger takes need a resource consent. Both the Heretaunga and Ruataniwha systems have been the subject of significant allocation and modelling work, and there are areas where new takes are constrained. Check the position for your catchment with the council before you commit to a drilling programme.

Before you book a rig

• Find out whether your property sits over the productive basin gravels or the hill country sequence.
• Pull the depth, screen, and yield records from bores near you.
• Check how much drawdown the existing takes around you cause at peak demand.
• Confirm the take you need is available and consentable in your catchment.
• Then give the driller a target depth and a preferred location.

A Bore Report does that assessment for your property. See also the guide to what a bore costs in New Zealand and the Canterbury guide.