Latest News

July 2008
Proposed national environmental standard for on-site wastewater systems

(this article can be found on the Ministry for the Environment website: click here)

The Government is considering developing a national environmental standard (regulations) for the inspection of on-site wastewater systems (such as septic tanks). The Ministry for the Environment is seeking public submissions and invites your views, which must be received by 5pm on Friday, 26 September 2008.

The aim of the proposed standard is to improve the management and environmental performance of domestic on-site wastewater systems. In essence, the proposal is that:

Owners of properties with on-site wastewater systems in specific locations will be required to hold a current warrant of fitness that confirms their on-site system is functioning properly and is being maintained to an appropriate standard.

The standard would authorise regional councils to require property owners with an on-site wastewater system to hold a current warrant of fitness (WOF) for their system. To obtain a WOF, a system would be required to pass an inspection every three years.

Regional councils would identify the areas where the standard would apply.

On-site wastewater systems provide treatment of domestic wastewater and return it to the environment within the boundaries of the property of origin. It has been estimated that in some regions at least 20 per cent of homes rely upon on-site wastewater treatment. On-site wastewater systems can include primary, secondary and tertiary treatment systems. Septic tanks are mainly primary treatment systems and they represent the majority of on-site wastewater systems installed in New Zealand.

For many areas in New Zealand, wastewater systems do not provide an adequate level of treatment and are adversely impacting on human health and the environment. Failing systems can:
  • 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 – affecting the quality of drinking water supplies – and may increase the occurrence of algal blooms.
These effects occur because of a range of factors including: poor maintenance, sensitive receiving environments (lakes, rivers, streams, etc), high density residential areas, shallow groundwater and unsuitable soil types. Regular inspections and maintenance can play a significant role in improving the performance of wastewater systems.

March 2008
Off the mains – treating home sewage

(Article on treating home sewage in Environs, March 2008 issue)

Is there a bad smell lingering in your backyard?
One patch of grass looking particularly green?
Skeptical of your septic tank?

If not operated or maintained properly, septic tanks and other on-site systems used to treat domestic wastewater can leak and pose a health and environmental risk.

“Poorly maintained or badly designed septic tanks can leach nutrients and bacteria into groundwater or through into streams or lakes," says civil engineer, Ian Gunn. "Of particular concern are the strips of developments along lakes where you have a whole lot of sections lining a lake shore or coastline. Often it’s the oldest properties using the oldest systems that line the lake shore.”

Septic tanks are just one type of on-site system that can treat domestic wastewater and return it to the environment within the boundaries of the property of origin. There are estimated to be around 270,000 domestic on-site systems in New Zealand However, the performance of those systems is quite variable.

Many studies and surveys carried out in recent years reveal that a large number of on-site wastewater systems in New Zealand are not performing in a way that provides acceptable levels of treatment. Untreated or partially treated sewage from these systems is causing public health risks and negative environmental effects.

The 'sniff and look' test is one way to find out if a wastewater system isn’t working. You know there is a problem if you can see patches of wet or smell a soggy silage odour, says Gunn. Without proper maintenance such as regular pump-outs, the tank or the trenches receiving the wastewater can overflow. Also, septic tanks in baches are a common problem in the holiday season when the systems get a 'shock load'. With the sudden influx of people, bacteria can’t cope with the waste entering the system.

“Owners must also use their systems sensibly. Many councils have a user's guide about what to do and what not to do. Owners should really be reminded regularly to check their systems. Some councils send out a reminder with the rates notice,” says Gunn.

According to Gunn, people should ideally be looking at the system ahead of a problem occurring. He says some councils already encourage proactive performance monitoring, and in some areas it is recognised that regular inspections are needed to get ahead of potential problems. For example, Environment Bay of Plenty has implemented a scheme in problem areas where they check every system and pump it every three years.

The Ministry is currently scoping the feasibility of a national environmental standard that would apply to the operation and maintenance of domestic on-site wastewater systems.
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