Stormwater and Your Home
If you are a landowner, it is your responsibility to manage the stormwater on your property. As well as managing the problem of potential flooding, there is also the need to protect the environment from the impacts of stormwater run-off and the pollutants and sediment that the stormwater picks up as it flows over hard and soft surfaces. See the figure, as shown below:
Stormwater and your home (image courtesy of ECan web site).
A private drain is any drainage systems constructed privately to service a single or small number of properties (combined private drainage).
The owner of the property or properties served by the private drain also own the private drain(s). If a public drain lies under private properties, then there should be an easement in place to allow ease of access for maintenance.
The owner of the property or properties served by the private drain is responsible for the private drain’s maintenance, up to and including the connection to any public drainage system.
When undertaking a new development, or if you are reconfiguring an existing lot, you should ensure that you manage your stormwater discharge without causing any nuisance flooding to any surrounding neighbourhood properties.
Any building activity, such as raising the ground level, increasing the impermeable area or blocking an overland flow path, could increase the amount of stormwater flowing onto a neighbour’s site. You must obtain a building consent or resource consent from the Council for such an activity. An on-site stormwater management device may be required as part of the conditions of the consent. Refer to On-site stormwater management devices for more detail.
It is illegal to intentionally direct stormwater onto a neighbouring property. If this does happen, the stormwater may cause damage to the neighbouring properties, which could lead towards a dispute or, at worst, legal action and subsequent compensation.
Reduce flood risks
Here are a few tips to reduce flood risks to your property:
- When constructing new buildings like homes, garages or sheds, think about how the stormwater will flow over the surrounding ground, remembering that it will naturally and inevitably collect in dips and channels.
- Reduce the amount of ground covered with impermeable surfaces, such as concrete or asphalt. Permeable surfaces absorb the water, thus reducing the risk of flooding and discharge pollutants.
- Never obstruct an overland flow path – this will cause inevitable flooding.
- Ensure that habitable floors (those areas of the house such as kitchens, bedrooms and living areas) are always the correct height above the surrounding ground level. This is to ensure that stormwater is not able to invade the living areas on your property.
Protect the environment
Everyone has a moral and ethical responsibility to keep the stormwater drains free of pollutants and contaminants. Washing your car in the driveway or rinsing paint brushes into stormwater drains can affect the quality of the natural water and harm plants and animals that live downstream (knock-on effects).
Property owners can help protect the environment by using features such as rain gardens and/or permeable paving, or by planting selective native bushes around the streams.
What is Stormwater?
- What is the difference between stormwater and other kinds of water?
- What do I do about a stormwater run-off from my neighbour's property flooding mine?
- Who is responsible for the maintenance of the waterway that runs through my property?
- What are the roles and responsibilities of individuals and councils in managing the risk of floods?
What is Stormwater runoff?
Stormwater runoff is rainwater that flows across the ground and does not get absorbed into the soil. It flows into stormwater pipes and streams, and from there into our estuaries and finally out to sea.
Stormwater can cause flooding, and can be harmful to the natural environment by picking up pollutants and carrying them into waterways.
What is the difference between stormwater and other kinds of water?
When talking about water, some common terms that are used are
- surface water;
- wastewater; and
Surface water is what we see in our rivers, lakes, streams, wetlands and estuaries.
Groundwater is the water that exists in aquifers beneath the ground. This is replenished by rainwater that travels through the soil.
Wastewater is the water that goes down drains from inside our house, after we do our washing, or flush the toilet or have a bath.
Stormwater doesn’t go into the sewers. It runs through a separate piped system from that of wastewater or across the ground.
What do I do about a stormwater run-off from my neighbour's property flooding my property?
It is a fact that stormwater flows from other properties naturally, either via an overland flow path or via a stream (from high ground to lower lying ground). It is your responsibility to manage stormwater falling and flowing naturally on your site.
If you have an issue with any of the following, you should first speak to your neighbour:
- Water flow problems caused by natural ground seepage on private property
- Diverting or blocking the natural flow of water from landscaping, fences and walls or a small trench
- Pool overflows caused by excessive rainfall
If you do something that increases the amount of stormwater 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 use systems to prevent the extra stormwater flowing across your boundary.
Council recommends you take the 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 legal advice, so that any agreement you made with your neighbour is legally enforceable and appropriate for future owners of the land should it be sold on.
Who is responsible for the maintenance of the waterway/drain that runs through my property?
If the waterway/drain is on private land, it is the landowner’s responsibility to resolve. If the waterway/drain marks the boundary then the area of it that is within your property is your responsibility.
If the drain is part of the council’s rated and maintained public stormwater network, then it is Council’s responsibility to maintain it.
What are the roles and responsibilities of individuals and Councils in managing the risk of flooding events?
When you buy a property or build a house or business, you can ask your regional council or local council about local flooding issues. If you are building, you can site your home out of any floodable areas, raise the habitable floor levels or make your house using materials better able to withstand floods.
Local councils are responsible for controlling new building and the effects of land use to reduce flood risk. They can put special controls on buildings to make the buildings safer from flooding. Councils can also set rules about where buildings can be located, where subdivision can take place, and the effects of land use. In a large flood, councils will coordinate with the emergency services and utility providers to minimise the impact of the flood on people and properties.
Regional councils manage rivers and catchments, and also control land-use activities through the Resource Management Act, as well as regulate large dams under the Building Act.