Property owners wanting to build in areas without a Council reticulated wastewater network all face a common issue: how to deal with their domestic wastewater in a manner that doesn't result in contamination of areas outside their property or waterways.
Effluent is disposed of on the property via a septic tank and effluent drainage field. These ground-based systems require regular inspection and maintenance to ensure they continue to operate effectively.
Older septic tanks should be checked at least annually to ensure sludge is not building up and effluent drainage fields should be maintained to ensure effluent is contained on your property and does not pose a hazard to people or animals.
When doing alterations to an existing dwelling by adding additional habitable spaces and bedrooms, consideration must be given to the size and capacity of the existing effluent disposal system and septic tank. Upgrading may be required. If Council records do not identify your septic tank capacity, a drain layer should be able to determine the size/capacity of the tank on site and provide a report to include with your application.
All new and upgraded effluent disposal systems are required to be designed by a suitably qualified consultant with full plans and specifications to be submitted with your building consent application. You should consult with an engineer or qualified drain layer to determine the type of system to suit your property and situation. A suitably qualified consultant will be able to carry out a site specific soil evaluation and design an effluent disposal system in accordance with AS/NZS 1547.
For more information go to www.level.org.nz/water/wastewater/on-site-wastewater-treatment/