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Questions and answers about the proposed National Environmental Standard for On-site Wastewater Systems

What is an on-site wastewater system?

On-site wastewater treatment systems provide treatment of domestic sewage and greywater and return it to the environment within the boundaries of the property of origin. They usually service one household. There are many different types of on-site systems, and they are designed to treat household wastewater to varying levels before it is released back into the environment. Septic tanks are a common example of a basic or 'primary' treatment system in New Zealand.

Why is a national environmental standard needed?

Ongoing maintenance backed up by regular inspections can play a significant role in improving the performance and life of an on-site wastewater system. A lack of maintenance has been identified as one of the main causes of failure. Failing on-site systems can:

  • create human health risks (such as gastrointestinal upsets, norovirus and hepatitis) from the overflow or ponding of effluent
  • contribute to lakes, rivers, estuaries and beaches becoming unfit for swimming, gathering seafood, and marine farming
  • lead to contamination of groundwater and surface water supplies, which affects the quality of drinking water supplies and may increase the occurrence of algal blooms.

How will I know if I will need a warrant of fitness?

If the national environmental standard proceeds, then it will be up to regional councils to decide who needs to hold a warrant of fitness. Regional councils will identify areas where the standard will apply. The criteria for identifying hotspot areas may include:

  1. locations with a history of problems with on-site wastewater disposal, identified through sanitary surveys or pollution hotline complaints or monitoring
  2. areas identified in plans or strategies as locations for intensification of land use, long-term growth or development, where sewage reticulation may not parallel development
  3. communities with a high proportion of on-site systems that use shallow groundwater for drinking water
  4. areas of highly seasonal occupation (relevant especially in attractive tourism spots) and not adequately designed on-site systems to cope with shock loads.

What are the costs?

It is estimated that an inspection to obtain the warrant of fitness will cost between $35 and $50, based on existing areas where inspections are required. Costs of repairing or upgrading a system are additional.

Who will carry out the inspections?

Inspections would be carried out by suitably qualified inspectors. Inspectors could be council officers or professionals that had been trained. If the national environmental standard proceeds then the Ministry for the Environment will develop a training package for inspectors.

How often will systems be inspected?

Systems would be inspected every three years

How do I know if my on-site system is not working properly?

Some of the tell tale signs are:

  • Foul smells around the system or lawn
  • Boggy areas on your lawn or garden, often with a grey or black slime
  • Toilets and sinks are slow to drain

Further information is available at: http://www.nzwwa.org.nz/FinalSepticUpdated06.pdf

Last updated: 6 January 2009