It is not surprising if you have a wet back garden as most of North Shore City has Waitemata clay soils, which do not drain well. 

Your boggy backyard is most likely the result of: 

• water from your own roof, driveway and other hard areas; or

• overland flow i.e. stormwater runoff from surrounding properties.

Overland flow

Overland flow is stormwater following its natural flow path and it needs to be dealt with by each landowner to suit their local situation. There is no magic solution. We recommend that you seek the advice of a drainlayer, consulting engineer or landscape architect.

What can you do?

You need to provide adequate stormwater drainage for your property. This may include:

A pipe system;

• Installing a rain tank and using your roof water in the laundry, toilet and for outdoor use;

• Reducing runoff by replacing concrete and asphalt with grass or porous paving; 

• Planting rain gardens and creating swales, open drains and soak pits to disperse stormwater and direct flow away from your house.

We recommend you work with your neighbours to find the most practical and workable way to solve overland flow problems.

Concentrating flows onto your neighbour’s property must also be avoided unless your neighbour can accept and deal with the flow without adversely affecting their own neighbours downstream.

What can we do?

We receive many requests for help from homeowners, however, we do not normally get involved unless the problem relates to a council-owned stormwater pipe or watercourse. 

What about a soak pit?

A soak pit or trench filled with scoria can help disperse overland flow. How well this works will depend on the subsoil type. Where there is clay soil the soak pit will overflow, and may spread surface water onto neighbouring properties.

Open drains

Open drains are a practical method of disposing of surface stormwater especially where neighbours can work cooperatively. Please get the agreement of adjoining owners to pass through their properties and seek council approval to connect to an existing stormwater system, if there is one in your area.

If they are properly maintained, open drains efficiently dispose of surface water. If piped, a shaped channel can be formed over pipes to allow excess stormwater to flow overland. 

Remember... Stormwater on private property is the property owner’s responsibility.