Stormwater

Our stormwater system is designed to protect you and your property from flooding.

Stormwater – often rain – is the water that enters drains outside your home and on the road, and any water that soaks into the ground. Wastewater is anything that enters drains inside your home.

We have developed a system of pipes over more than 100 years that carries excess stormwater straight to our streams and rivers. This system includes about:

  • 5,511 manholes
  • 290km of piped drains under the road
  • 20km of open drains

See how our stormwater system prevents our city from flooding.

Look after your gutters and drains

Rain collected on your roof travels through spouting and downpipes, before flowing into our stormwater system (usually outside on the road).

Each homeowner must dispose of their stormwater runoff in a way that avoids the likelihood of damage or nuisance to neighbouring properties. If your stormwater runoff causes damage to someone else’s property, you will be required to fix the situation.

It’s a good idea to regularly check the drains and gutters outside your home to ensure they’re not blocked and working as normal.

We’ve created these guidelines for residential developers to better manage stormwater in new developments.

Image shows a black dog sitting in front of a pond and stormwater culvert.

Here is one of our stormwater culverts at Linklater Park in Kelvin Grove. 

Run-off from your neighbours

You are only obliged to accept stormwater runoff from properties which would naturally discharge onto your property.

Any improvements to properties must ensure that extra stormwater is controlled and does not cause a nuisance or damage.

If your neighbour’s runoff is damaging your property, we recommend you take the matter up with your neighbour directly. Council will only intervene where the runoff is the direct consequence of construction that Council has given consent to.

Please be aware that if you do any development on your property it may increase the amount of stormwater flowing onto a neighbour's property. Raising the ground level, increasing the impermeable area or blocking a flow path are all likely to impact someone. You will either need to stop that activity or prevent the extra stormwater flowing across your boundary.

Council recommends you take time to talk to your neighbours about any flooding problems you may be 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 if the land should be sold.

Don’t connect your gutters to our wastewater network

A cross connection is the diversion of stormwater into the wastewater network.

A common source is a downpipe diverted into the gully trap (a drainage vent usually covered with a small grating and located against the outside of a house, near the kitchen, laundry or bathroom).

Stormwater in the wastewater network can overload our wastewater treatment plant, which forces us to discharge partially treated water to the Manawatū River so the plant can keep up. Wastewater connections to stormwater pipes have an equally harmful impact.

One way to help keep our streams, rivers and coast clean for generations to come is to ensure there are no cross connections on your property – they are illegal. 

It is the homeowner’s responsibility to ensure their drainage pipes connect to the right system.

Photo shows a gully trap on the ground.

Pictured is a gully trap. Down pipes from the roof and other stormwater pipes cannot connect to these.

Protect our streams

Stormwater runs through a network of pipes before being discharged into nearby streams or rivers.

We have consent from Horizons Regional Council to do this because, unlike wastewater, stormwater does not need to be treated prior to being discharged as it is not contaminated by chemicals or waste.

Household products kill fish

You might not be aware, but hazardous household products enter our stormwater network when they are poured into your outside drains.

Disposed oils, detergents, paint, solvents, pesticides and other common household products contain chemicals that are toxic to fish. Even small discharges poison our waterways.

Do not pour anything into a stormwater drain that could be toxic to wildlife. This includes:

  • Paints and solvents
  • Pesticides
  • Motor oil
  • Diesel
  • Petrol
  • Washing detergent
  • Degreasers
  • Disinfectants
  • Drain and toilet cleaners
  • Dry cleaning agents
  • Household cleaners

How you can look after our stormwater system

We’re likely to continue experiencing severe weather events, so we need your help to reduce the chance of flooding.

You can help by:

  • Picking up rubbish and leaves
  • Clearing your drains of other material
  • Never dumping garden waste near water

Here’s 10 things you can do to prevent polluting stormwater runoff:

  • Never tip paint or chemicals out near a drain
  • Direct downspouts away from paved surfaces
  • Vegetate bare spots in your yard
  • Compost your yard waste
  • Picking up your animal poo
  • Use least toxic pesticides, follow labels and learn how to prevent pest problems
  • Consider starting a rain garden
  • Take your car to a car wash instead of washing it in your driveway
  • Check your car for leaks and recycle your motor oil