Surface Water

Council owns, operates and maintains the public stormwater network. This includes:

• public stormwater pipes, sumps, manholes and outlets
• stormwater pump stations
• public open drains and urban watercourses that form part of the network.

The public network is designed to carry stormwater from normal rainfall events. In very heavy or intense rain, the volume of water can exceed the capacity of pipes and pumps. When this happens, water will flow over land, including along roads and across private property.

Council’s stormwater work programme and funding are set out in the Long Term Plan and Annual Plan.

Buller, Grey and Westland District Councils have established Coast Waters Ltd, a jointly owned water services organisation. Coast Waters will take over delivery of drinking water, wastewater and stormwater services across the West Coast. Until the transfer takes place, Grey District Council remains responsible for stormwater services. We will update this page when arrangements change.

The West Coast Regional Council is responsible for river and coastal flood protection, including the Greymouth Floodwall. West Coast Regional Council also regulates the discharge of collected stormwater runoff into or onto land. (see Rule 81 of the West Coast Regional Land and Water Plan). For questions about river levels, stopbanks or the Greymouth floodwall, or discharge of stormwater to land, contact the West Coast Regional Council.

Property owners are responsible for the private stormwater system on their property, up to the point where it connects to the public network. This includes:

• roof gutters and downpipes
• private stormwater pipes, sumps, soak pits and connections
• private drains and channels.

Property owners should:

• keep gutters, downpipes, sumps and private drains clear and in good repair
• not block, divert or concentrate overland flow onto a neighbouring property
• not build, fill land or place fences or structures in a way that blocks an overland flow path
• not put anything other than rainwater into a stormwater drain.

If you have a blocked or damaged private stormwater drain, contact a registered drainlayer or plumber.

Building work, including site work, must comply with the New Zealand Building Code. Clause E1 Surface Water requires that:

• surface water from a 10% annual exceedance probability (AEP) event that is collected or concentrated by buildings or site work is disposed of in a way that avoids damage or nuisance to other property (E1.3.1)
• surface water from a 2% AEP event does not enter housing, communal residential and communal non-residential buildings (E1.3.2).

When you apply for a building consent, you will need to show how stormwater from the building and site will be managed. Where land is subject to a natural hazard, including inundation, the Building Consent Authority must also consider sections 71 to 74 of the Building Act 2004.

The Building Consent Authority’s role is limited to checking that building work complies with the Building Code and the Building Act. It cannot resolve drainage disagreements between neighbours or require upgrades to existing work that was lawfully built.

Water naturally flows downhill. A property lower down a slope will receive some natural run-off from the property above. This is normal and not something Council can prevent.

If you believe a neighbour’s building work, earthworks or private drainage has changed or concentrated the flow of water onto your property:

1. Talk to your neighbour first. Many problems can be fixed with simple maintenance.
2. If the issue relates to building work, contact Grey District Council’s Building Team on 03 769 8625 or building@greydc.govt.nz to check whether a building consent was required or issued.
3. If the matter is not within Council’s jurisdiction, it may be a civil matter between property owners. You may wish to seek independent legal advice or use a mediation service.

If life or property is at immediate risk, call 111.

Contact Grey District Council’s Infrastructure Team on 03 744 7147 or gdc_infrastructure@greydc.govt.nz if you notice:

• a blocked or damaged public sump, pipe or manhole
• a blocked public open drain
• flooding from the public network
• contaminants such as paint, oil or chemicals entering a stormwater drain.

Contact West Coast Regional Council on 03 768 0466 or info@wcrc.govt.nz if you notice:

• a stormwater discharge to land (not Council drains) causing erosion, scouring, land instability, sedimentation or ponding beyond the boundary of the subject property
• a discharge to land containing contaminants.