The AES System

The AES Wastewater Treatment System

AES (Advanced Enviro-Septic™) is a high quality, reliable, cost competitive, environmentally sustainable, maintenance- free on-site wastewater treatment system that will save you money.

Features & Benefits

Exceptional Quality of Treatment

  • Highest secondary treatment levels – treatment results are 10 times better than Aus/NZ Standard 1547 for Secondary Treatment when tested at NZ’s OSET-NTP.
  • AES achieves very high pathogen reduction, without using disinfection such as UV filters or chlorination.

A Silent, Reliable System

  • Noise-free without pumps or alarms.
  • Maintenance-free. No regular checks needed by homeowners or plumbers. Just empty the septic tank when needed.
  • Power-free

Fit and Forget

  • No electronics or moving parts to replace – i.e pumps, control boards, aerators or blowers.
  • No membranes or replacement media to clean and replace.
  • No chemicals to add.
  • Just empty sludge from the septic tank every 5-7 yrs as for any septic system.

Advantages over other Systems

Cost Savings

  • Over $1,000 annual savings – in power costs, servicing contracts, filters, membranes, additives or chemicals.
  • No costly annual maintenance contracts. Most councils require homeowners to have their septic system serviced at least every 6 months. This is not required with the AES system.
  • No pump to replace at minimum $1,000.

Natural Treatment, Safe for the Environment

  • No added chemicals
  • AES uses natural biological processes to treat effluent.
  • The high quality of treatment and long life of the system protects groundwater from contamination and minimises risk of health issues.
  • Local – AES uses local installers, locally sourced septic tanks and locally sourced system sand.


  • No worm casts to dispose of every 6 months.
  • No need to restock worms when they die.

Design Flexibility

  • AES installations are adaptable to many site conditions with various design options available.
  • AES systems can be used for greywater only, blackwater only and combined all‐waste systems. Treated effluent can be collected and used for irrigation.
  • An AES treatment bed can be straight or curved (up to 90 degrees), follow contours or fit around objects
  • AES can be installed under driveways.
  • For areas with high groundwater AES can be installed in a raised bed.
  • Treatment beds can be landscaped with grasses or other shallow rooting plants.
  • AES can be installed in new projects or retrofitted to an existing septic tank to upgrade to secondary treatment.

Proven Long Life & International Reputation

  • AES components are extremely durable and last indefinitely. An AES system will keep on working for you. Systems unearthed after 15-20 years have been shown to be functioning as installed with clean, unclogged sand beds.
  • 20-year warranty on components – longer than any other system.
  • Premier system worldwide. AES systems have been installed in the USA, Europe, Australia, South Africa and many other countries for over 25 years with long-lasting and reliable results.
  • Rigorous testing in North America, Europe, Australia and NZ shows consistently high quality results.

Systems Comparison

AES compares very favourably with other on-site wastewater treatment systems.

How On-site Septic Treatment Works

There are 3 levels of on-site septic treatment.

Primary Effluent Treatment
Raw effluent flows from a building or ablution block into a septic tank. Here, initial treatment is anaerobic (without air) as microbes in the effluent consume some of the suspended organic material. Inorganic material settles to the base of the tank and a scum layer floats on the surface sealing the majority of the effluent off from the air within the tank. Overflow from this tank is disposed of into a bed in the ground.

Secondary Treatment
Secondary effluent treatment is often a council requirement, and treats effluent to a higher level. Secondary treatment may be required when the disposal bed following primary treatment is on too small an area of land, is close to surface water or there is concern about groundwater contamination. Secondary treatment involves aerobic (in the presence of air) microbes resulting in the almost complete removal of dissolved and suspended organic matter from the effluent.

Dispersal to Ground
After these treatments, the effluent is usually required to be dispersed to a bed in the ground where soil bacteria and microbes in the soil consume whatever nutrients are left.

How AES works

AES onsite wastewater treatment system - how it works

AES is a passive, on-site advanced secondary wastewater treatment system developed and in use in the USA for over 25 years with over 500,000 installations. Gravity fed from a septic tank, effluent is treated using naturally occurring microbes within specially designed, passively aerated pipes laid in a sand bed.  The remaining highly-treated effluent is evenly dispersed via perforations in the AES pipes into the sand bed or can be collected and used for irrigation if preferred. Within the sand bed, there is further microbial breakdown.

The key to the success of the AES system is passive ventilation through specially designed AES pipes which provide an environment for the microbes in the effluent to be processed to a safe level. A standard AES system does not require pumps, filters or any maintenance. All that’s required is a routine septic tank pump-out every 5-7 years. AES is simple, using the processes of nature, environmentally sustainable and very effective.

The essential AES treatment process occurs in specially designed, 300mm diameter, oxygenated pipes installed in a sand bed in the ground. Effluent flows via gravity into the AES pipe system from the septic tank and is exposed to a culture of naturally occurring microbes that break down solids and digest potential organic pollutants more rapidly in the presence of air. Based on a ‘chimney’ effect, air is drawn into a low-level inlet vent at one end of the system of AES pipes and naturally flows through to a high-level vent at the other end.

AES pipes

AES pipes have been especially designed in the USA. A mat of coarse, random fibres completely covers the pipes providing additional surface area for the microbial breakdown of solids and bacteria to take place. Skimmers on the interior capture grease and suspended solids from the effluent. Bio-Accelerator™ fabric at the base of the pipe facilitates the development of a biofilm of self-colonising microbes that process the organic material. By reducing permeability this biofilm also ensures the effluent extends the entire length of the pipe.

AES wastewater treatment system

Why AES is the best system by David Presby, inventor of AES

Part one
Part two

Steps to get an AES system

  • Step 1 to get an AES system
  • Step 2 to get an AES system
  • Step 3 to get an AES system

Our team can answer any questions you have about the AES combined treatment and dispersal system and how it will fit your site.

We can give you a ballpark cost and organise an on-site assessment for a wastewater design by one of our accredited AES designers in your area.

The AES designer will visit your site and in conjunction with you determine the best placement of the system in relation to property, boundaries, water sources, your soil category, underground water table etc., and in accordance with NZ standards and your local council rules.

From this, the AES Designer will create a design report for inclusion with your building consent application.

Environment Technology peer reviews the AES design for your added confidence.

With approved consent, the installation can proceed. You can either call us and we will arrange for a price/s from local AES certified plumber/drainlayer installers, or your preferred drainlayer can become AES certified by completing our free online training course.
The installer will arrange for the purchase and delivery of AES components and the supply of a locally produced septic tank. They assemble the components and install the system as designed.

Your AES system will immediately start functioning. You can relax knowing there is a 20-year warranty on all AES components, and no need for maintenance contracts, regular inspections, or cleaning of filters.

Technical Advice and Quality Assurance

Environment Technology, NZ-wide distributors of the AES system, provide free technical advice and peer review all designs for council submission.

All AES system designers and installers need to have completed the Environment Technology free online certification course which provides comprehensive information and training on the design and installation process.

The 20-year warranty on all AES components provides peace of mind.

The NZ test results at OSET-NTP in the table on the right speak for themselves.



The cost of a system depends on the specifics of the site, the system size and the particulars of your Council’s compliance. In general, you can expect that AES technology will cost 20% less than a conventional pipe in a trench with a drainage metal system. When compared to other Aerated Wastewater Treatment Systems (AWTS) with power requirements, complicated computer control systems, compressors or blowers and a variety of pumps, the initial AES installed cost will be competitive but then there will be no ongoing costs – no service inspections required, no power, nothing to break down and requiring replacement.
Contact us to discuss your project and answer any questions. We will provide you with a local certified AES Wastewater Designer and when your project is ready to go we can give you contact details of local AES Certified Installers.
The size of a typical AES System varies depending on site and soil conditions, however you can expect at least a 40% reduction in dispersal field size. This should also translate into lower installation costs.
If the septic tank is properly sized for waste disposal use and equipped with baffles, the AES system’s size does not need to be adjusted. The use of a waste disposal unit adds considerably more solids to a septic system than are usually present. This typically requires a larger septic tank and more frequent pumping out. Please inform your system designer of your intention to install a waste disposal unit for this reason. Often, waste disposals are installed at a later date after the septic tank system has been determined and installed. If this is the case we recommend that the AES bed size is increased by 10%.
Grass, shrubs, flowers and ground covers with non-invasive roots are the best choices for vegetation over the treatment field. There should be no trees planted within 3 metres of any part of the treatment field, to prevent damage to the system from root infiltration. Particularly do not plant willows, figs, bamboo, citrus or blackwood to name a few. Do not plant gardens for human consumption within 1m of the drain field.
Ride on mowers are fine and heavy vehicles only if it was designed for vehicle traffic loading. This involves the construction of load bearing aggregate layers over the AES bed. Driving over an AES field can cause damage if the system was not designed for traffic bearing loading. If your AES System was not designed and/or installed to allow for vehicular traffic, try to keep traffic over the treatment field to a minimum. Use particular caution with the following as they may compact soils and inhibit oxygen to the system:
  • Farm equipment/grazing animals
  • Construction equipment
  • Repeated use of Farm Bikes, ATV’s, motorcycles, etc.
  • Mowing equipment is fine
No. The additional water from irrigation systems could flood the system and adversely affect its operation. For the same reason, drains, sump pumps, gutter systems, etc should not discharge into or near the system. Grading and surface diversions (swales) should be located so as to redirect storm water run-off away from the system. The ground surface over the treatment field should be crowned in order to prevent ponding of surface water over the treatment field.
While moderate amounts of bleach and disinfectants don’t measurably disrupt the treatment process, excess use can cause the amount of anaerobic bacteria to plummet in the septic tank. However, tests show less disruption and quick recovery of aerobic bacteria in the AES pipes from this disturbance. The self-colonising bacteria involved in the treatment process thrive on regularity yet adapt to the feasts and famines of shock loading and intermittent use by reducing and recolonising on demand without outside intervention. One of the top benefits of an AES system is that it has no filters to be cleaned or complicated electronic or moving parts to break down. Self-recovery from a myriad of issues can occur, including cases where the micro-organisms responsible for the treatment are chemically poisoned. One idea is to use a bucket for bleaching and dispose of outside and not down the sink.
Yes. The usual site conditions will need to be taken into account, such as the permeability of the soil and the depth of the water table below the AES bed. Ask your wastewater designer or call us for advice.
Yes. The system relies on aerobic bacterial treatment processes, so a supply of oxygen is essential. Generally a 3 metre vertical height separation between the low level air inlet at the AES bed of 100mm diameter pipe with a simple vent cap and a similar high level air outlet vent is required. There are a number of ways to minimize the visual impact of these vents – the simplest is using the terminal vent on an adjacent building.
Usually the limiting factor on how deep an AES System can be buried is the depth to the seasonal high water table or some other restrictive feature. If the soil profile in your area includes relatively impermeable higher level layers and there are free draining horizons at depth and the water table is not a restriction then the AES field can be constructed at a suitable depth to make use of this enhanced permeability.
No. AES systems were thoroughly tested in Canada in order to confirm that extreme winter conditions do not have an adverse effect on the functioning of the system. In general, septic systems are not prone to freezing. Bacterial activity generates heat, and the septic field is regularly dosed with warmer water from the septic tank. Distribution boxes can freeze because of improper venting or a lack of foam insulation, but this is rare even in cold continental climates.
If the system is designed, installed and maintained properly, there is no limit to the life expectancy of an AES System. In the very rare event that the system malfunctions due to some form of abuse, usually that the air supply is compromised, AES may be rejuvenated in as little as 72 hours by draining the system and restoring the air supply eliminating the need for a replacement.
No. The AES online training and certification course is available to anyone interested, free of charge whether you just want to learn more about our system or if you are seeking certification. See online training course.

AES System Design

Yes. The low vent may be attached to the d-box and the high vent may be attached to the end of the field. If this configuration is used in cold climates, the d-box must be insulated to prevent it from freezing. Please see Venting for more information.
Yes. The low vent can be located at the same end of the field as the high vent as long as there is a continuous serial connection incorporating all the AES pipes between inlet and outlet vents. This will mean that there has to be an even number of AES rows in the bed. The high vent will require some support or be constructed of some sufficiently rigid and anchored pipe.
The house roof terminal vent functions as the high vent as long as there are no restrictions, air inlet points or other vents between the low vent and the roof level vent on the building. A minimum of one 80mm diameter or 2 x 50mm diameter vent pipe(s) are required. Please see Venting for more information.
Yes, however, effluent filters are not recommended due to their tendency to cut off the essential air supply to the AES pipe system even when they are properly installed and maintained. This is an issue if the terminal vent on the house is being used as the high-level air outlet vent – in other words, the airflow to the outlet is dependent upon an airflow across the top of the septic tank. If you are required by your local authority to use an effluent filter in a gravity fed system, the effluent filter selected must allow the free passage of air to ensure the proper functioning of the system. The design should also incorporate an air bypass to allow for the filter becoming blocked for any reason including lack of maintenance. If a filter is used, the manufacturer’s installation and maintenance instructions should be followed carefully and the filter inspected regularly.

AES System Installation

No. After system sand is spread between rows we recommend that the installer straddle each row of pipe and walk heel-to-toe its entire length, ensuring that system sand fills all void spaces beneath and between the AES pipes. Pneumatic-tyred equipment and/or mechanical compactors should not be used to compact system sand, backfill or fill extension areas. Mechanical compaction will damage the soil’s ability to disperse liquid and may inhibit air supply to the entire system.
Yes. Glueing is highly recommended to ensure connections remain assembled during the backfill procedures.
No. During installation, the fabric will typically reach or cover part of the fitting. We recommend sandwiching the white accelerator fabric within the coupling if possible. If the fabric falls short of reaching the fitting, it is no cause for alarm. Installers can very easily pull or push the pipe to make it slightly longer or shorter. If space remains between the fabric and fitting, the system sand will bridge over-exposed pipe perforations, preventing additional system sand from entering the pipe and suspended solids from exiting the pipe.