Frequently Asked Questions

What is an Aerated Sewage Treatment System?
It is a device comprised of tanks, pumps, filters and various other components , that takes the outflow from a normal septic tank and further processes it, using natural biological processes, to produce effluent that is no longer destructive to the environment.

How does an Aerated SewageTreatment System work?

It works by providing an environment where massive colonies of helpful bacteria can establish themselves, and by providing those bacteria with the food and oxygen that they require to thrive. The food on which these colonies thrive is the organic material contained in the waste outflow from the septic tank. In order to consume and process the inflow to the system, the bacteria colony requires a large amount of oxygen. This oxygen is introduced into the system using electrically driven pumps or blowers.

What do Treatment systems cost to run?
Most systems utilise electrical energy to introduce dissolved oxygen into the treatment flow. The amount the system costs to run depends on the type of system and the type of pump fitted, as well as how long each day that the pump is active. The cost of operating a system can range from 1.3kWh (electrical units) per day thru to 8.5kWh (electrical units) per day. A single electrical unit can vary in cost depending on where you live, but is typically in the order of 20 cents per unit, so you’re not likely to pay more than $1.70 per day.

How much does each system cost to purchase and install?
The actual cost of a system varies depending on many factors. The location of your property is a major factor since that determines the degree of sensitivity to environmental damage as well as the soil type involved. The soil type is significant because its ability to absorb the final outflow from the treatment system. Poor soils, in this respect, require additional length of irrigation drip line and this adds cost to the system. Delivery charges also affect the cost. We can provide you a quote based on your requirements and location, contact us to arrange a quote.

What is the National Test Field?
The ‘National Test Field’ is a recent government backed initiative to establish a facility that can monitor and test all Waste Treatment Systems. It is located in Rotorua primarily because this region has a very high sensitivity to pollution from sewage waste as is evidenced by the problems with weed and algae in the many lakes in this area. The National Test Field provides an environment where AWTS systems can be quantitatively monitored, both for their input and their output, and from these results determine the ratings for the system. All AWTS sold in New Zealand will be required to pass through this national certification process.

How do I know what would be the best system to use for my situation?
The best system for your situation depends on a number of factors:

  1. How many people will be using the system. This depends on whether it is a household or a commercial installation
  2. The level of environmental sensitivity of your location.
  3. Local and Regional Government regulations.
  4. Site constraints i.e concrete or plastic.
Which system has the best performance?
The systems with the highest level of performance are currently those that are certified for use in the Bay of Plenty region. Such systems are required to reduce the nitrogen content of the outflow to a negligible level so as not to disturb sensitive environments. Our Econo-Treat ® VBB-C-3000 unit has been certified for use in such areas so represents our best performing system.

What is the difference between various models?
All our models are based on the Econo-Treat® VBB-2200 technology. They are scaled up and down based on how many litres a day are required.

Why is there a choice of concrete or plastic tanks?
All of our systems can be built into both plastic or concrete tanks.  Plastic versions are more suitable for site locations where access is restricted such that our hiab truck cannot be utilized for installing the tanks. Such locations include islands where access is by ferry. Concrete is generally the cheaper option, unless there are special circumstances.

What guarantees do you offer for each system?
We offer a 15 year warranty on all concrete and plastic tanks and pipeworks along with a 2 year warranty on all irrigation pumps. Air blowers from Nitto carry a 3 year manufacturers warranty.

Do you have a model that is approved for use in the Bay of Plenty area?
Both our systems are certified for the most sensitive area in the Bay of Plenty area, including the Rotorua Lakes catchment. You can download our Environment Bay of Plenty performance certificates here.

How often do I need my system serviced?
All our systems require once a year servicing.

How do I know which system to choose?
Normally your Engineer will advise you as to which systems are suitable for use in your particular situation. This depends on factors mentioned here, including your location and the number of people involved. In many cases the final decision comes down to economics, both in the cost of the unit, the installation of the units, and the ongoing running costs.

What are the benefits of an aerated system over a traditional septic tank and field soakage trench system?
The outflow from an aerated waste treatment system contains very low levels of environmentally hostile material when compared to traditional septic and soakage systems. Consequently the outflow can safely be used to irrigate hedges, lawns, orchards and gardens.

Who can I ask for advice?
You can contact us and we’ll only be too happy to help with any questions you may have. If building a new home, your engineer should also be able to give you advice on which system to select for your situation.
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