Stormwater

Stormwater collects on the roofs of houses and is removed from the roof through spouting and downpipes. The water should then flow to a Council stormwater system (where available), a private stormwater system or a private soak hole within the property.

Every homeowner has the obligation to dispose of their stormwater runoff in a way that avoids the likelihood of damage or nuisance to other property. If stormwater runoff from your building is causing damage or nuisance to another property, you will be required to fix the situation and may expose yourself to liability for damages.

This is provided under Clause E1.3.1 of the NZ Building Code E1, which states that “any event that has a 10% probability of occurring annually and which is collected or concentrated by buildings or site work shall be disposed of in a way that avoids the likelihood of damage or nuisance to other property”.

Additionally, it is illegal to introduce any hazardous substances into any part of the stormwater system, as this water is eventually inhabited by wildlife. These hazardous substances can also impact on people when they are introduced into stormwater systems.

If stormwater is not carried away quickly, flooding can occur, resulting in property damage and sometimes personal danger

You are only obliged to accept stormwater runoff from properties which would naturally discharge onto your property. Any improvement made to sites must ensure that the extra stormwater is controlled and does not cause a nuisance or damage to your property.

If your neighbour’s runoff is causing a nuisance (which directly affects you or your property) or damaging your property, it is advisable to take the matter up with your neighbour directly.

Council will only intervene where the runoff problem is the direct consequence of a building consent that Council has given consent to.

Please be aware that if you do any development on your property it may increase the amount of storm water flowing onto a neighbour’s site, such as raising the ground level, increasing the impermeable area or blocking a flow path, either stop that activity or cause, or prevent the extra storm water flowing across the boundary.

The best solutions to storm water problems is to manage the problem as close to the source by reducing run off and decreasing impermeable surface area.

Council recommends you take time to talk to your neighbours about any flooding problems you maybe experiencing. In many cases, a resolution can be reached that will satisfy everyone’s needs.

You may need to consult a lawyer so that any agreement you make with your neighbour is legally enforceable and appropriate for future owners of the land should it be sold.

Council provides reticulated piped stormwater drainage systems in urban areas. These systems carry your property’s stormwater into local streams and rivers.

Council must have consent from the relevant regional council to discharge stormwater into waterways.

Manawatū District Council has a stormwater connections/ disconnections process that enables Council to manage the stormwater network.

Visit www.mdc.govt.nz for information on how to connect and disconnect to the Manawatu District Council’s stormwater system

Be flood wise - build with nature not against it.

When designing new buildings like homes, garages or sheds think about how the storm water will flow over the ground, remember it will naturally and inevitably collect in dips and channels.

Reduce the amount of ground cover with impermeable surfaces such as concrete or asphalt. Permeable surfaces absorb the water reducing the risk of flood and pollution. Consideration must be given to stormwater from hard stand surface areas and where this water is to be reticulated.

Never obstruct an overland flow path - this will cause flooding.

Ensure that habitable floors (those areas of the house such as kitchens, bedrooms and living rooms) are always the correct height above ground level to ensure that storm water is not able to encroach into the living areas of your property.

If I have drainage problems within my property, including soak holes?

A plumber.

If my neighbour’s runoff is causing a nuisance damage?

Your neighbour.

For blocked stormwater mains and open drain problems.

Council’s Operations team.

For local road drainage and culverts.

Council’s Roading team.

For state highway road drainage and culverts.

NZ Transport Agency, Freephone 0800 444 449.

For rivers, streams, land drainage in rural areas and flooding issues.

Horizons Regional Council

For any further stormwater problems.

Manawatu District Council

For hazardous substances/pollution control.

Horizons Regional Council/Manawatu District Council.