Stormwater is rain that runs off our houses, footpaths, roads and carparks. It runs into gutters and drains that flow into the stormwater system.

Stormwater collected in the stormwater system is discharged directly into Timaru District’s streams, rivers and the sea.

When talking about water, some common terms that are used are:

• surface water
• groundwater
• wastewater
• stormwater

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 to that of wastewater or across the ground.

Stormwater is discharged, untreated, into streams and rivers so it's important that it is as clean as possible.

If contaminated stormwater pollutes the river and streams, this can have a negative effect on aquatic life, the natural environment and public health. It can also limit recreational use of local waterways. 

Contaminants such as debris, fats and oils can build up in the stormwater system causing blockages that may damage the system and cause flooding.

We all have an important role to play in protecting the stormwater system. The public is responsible for ensuring contaminants, like paint, chemicals, fats and oil don't enter the stormwater system. Landowners are responsible for managing stormwater runoff from their land to avoid polluting our waterways. 

Timaru District Council is responsible for managing the discharge of stormwater from our public stormwater systems into streams and rivers. Environment Canterbury is responsible for ensuring our freshwater ecosystems are protected. They do this through setting Regional Plan rules and issuing resource consents that control discharge of contaminants into water (as well as onto or into land and air).

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 onto 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

Council recommends you 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.

Activities like raising the ground level, increasing your impermeable area or blocking a flow path can increase the amount of stormwater flowing to your neighbour's site. If you have altered or modified your property and this is causing a neighbour's property to flood, you should either stop the activity or implement a system to prevent the extra stormwater from flowing across your boundary.

Local councils' Building Units are responsible for controlling new buildings 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' Planning Unit 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.

Environment Canterbury manages natural waterways in the Canterbury area including river catchments. They also control land-use activities through the Resource Management Act, as well as regulate large dams.

When you buy a property or build a house or business, you can ask about local flooding issues and purchase a Land Information Memorandum (LIM) on a property you are considering buying. The LIM will record any flooding of habitable floors.

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.

The Council provides guidance on what can and can't enter the stormwater system and offers practical stormwater solutions through its education programme.

There are a number of stormwater issues to manage. They include:

• Hazardous substances such as oil and chemicals being discharged into waterways and affecting ecosystems.
• Wastewater entering the stormwater system through illegal connections which then get into waterways where people swim.
• Stormwater getting into the wastewater network which overflows into waterways and onto land in heavy rainfall.
• Uncontrolled sediment entering the stormwater network. This can build up in parts of the network which affects the capacity of the system.
• Damage to pipes and modifications to established overland flow paths which can increase risk of flooding.

• Flood protection & Drainage bylaw (Environment Canterbury)
• Drain maintenance (Environment Canterbury)