Envirocycle Septic Systems: An Owner’s Guide to the Oxyfix, Older Model 10 NR Units, Servicing and Faults

An Envirocycle is an aerated wastewater treatment system (AWTS), not a plain septic tank. It settles and digests solids in a primary chamber, aerates the liquid so oxygen-loving bacteria can finish the job, clarifies and disinfects it, then pumps the treated water to an irrigation area. The only Envirocycle a council can approve for a new install in NSW today is the Oxyfix, made by AWTS Maintenance Services Pty Ltd at Heatherbrae in Port Stephens.

Older Envirocycles are still in the ground too, including the Model 10 NR, which was built around ultraviolet (UV) disinfection rather than chlorine. This guide covers both: what the Oxyfix certificate actually says, how the older units were meant to be looked after, what goes wrong, what repairs cost, and what an old unit means on a property you’re buying. For the wider brand picture, our AWTS brands compared article gives Envirocycle one row alongside Biocycle, Ozzi Kleen and others.

Who makes Envirocycle, and what is on the register now

Envirocycle is a trading name of AWTS Maintenance Services Pty Ltd, based at Heatherbrae, near Raymond Terrace, with a Queensland office at Beerwah. The company says the Envirocycle dates from 1982 and describes it as the only aerated wastewater treatment system to receive an Australian Design Award, in 1984. Those are the manufacturer’s own claims.

As at 28 September 2026, the NSW Health register of accredited AWTS lists one Envirocycle model: the Envirocycle Oxyfix AWTS for up to 8 persons, certificate STS-AWTS064, issued 7 November 2022 and expiring 31 December 2027.

The Model 10 NR and earlier Envirocycle models are not on the current register. That doesn’t make an installed one illegal. An existing system keeps operating under the approval your council gave it, and you keep servicing it. What changes is that a council can’t approve a new install of an unlisted design, and parts and service support depend on the manufacturer still backing the model.

How an Envirocycle Oxyfix works

The certificate describes one concrete vessel, made by Allcast Precast, with a total fluid capacity of 7,200 litres. Inside, the wastewater passes through these chambers:

Air comes from an RLB80T aeration pump “or similar”, rated at a nominal 120 litres a minute at 1.3 metres depth. The irrigation pump is a Reefe RVS155 or equivalent. A control unit watches both pumps, with a warning lamp on the tank and a mutable warning panel inside the house.

Any random grab sample of Oxyfix effluent must meet the certificate’s limits: BOD under 30 mg/L, suspended solids under 45 mg/L, E. coli under 100 cfu per 100 mL, and free chlorine between 0.2 and 2.0 mg/L. Separate testing reported a 36% cut in total nitrogen and 22% in total phosphorus. The treated water can go to spray, mulched surface drip, subsurface drip or sub-soil application, each subject to council approval.

Older Envirocycle Model 10 NR units

If your system predates the Oxyfix, check the plate for a Model 10 NR. The manufacturer’s 2004 Envirocycle Handbook for the Model 10 NR describes a 10-person unit in a round concrete tank about 2.48 metres across, holding roughly 7,000 litres. “NR” stands for nitrate removal.

The big difference is disinfection. The Model 10 NR ran clarified water past a UV lamp instead of chlorine tablets. The handbook says earlier Envirocycles used chlorine, which it called unreliable and maintenance-heavy, so an older unit without the NR badge may not be UV at all. What that means if you own one:

• The UV lamp has a limited life. The handbook gives it a one-year warranty and a five-year expected service life, the same as the control box, alarm panel, irrigation pump and air pump.
• The alarm panel reads differently. A yellow light with the buzzer meant low air pressure, a red light with the buzzer meant high water, and both lights together meant a UV fault.
• Servicing was every four months. The handbook sets a full check of the plant, blower, pump, UV light and electrics four-monthly, and notes the Model 10 NR “only requires 3 services per annum”.
• Air pump parts had a set life. The handbook says the air pump has components that must be changed every 16 months at the owner’s cost.

Servicing an Envirocycle: how often, and who can do it

Envirocycle owners get mixed messages on frequency. The Oxyfix certificate, clause 3.3, says the system “shall be serviced at four (4) monthly intervals”. Clause 3.5 of the same document then lists what “each three-monthly service” must include. Hunter councils generally expect an AWTS to be serviced quarterly. And Envirocycle’s own servicing page, written for all the residential and commercial systems it services, says most benefit from “biannual visits”.

Go by the one that binds you: your council’s approval to operate. The certificate says councils apply its conditions to that approval under clause 45(4) of the Local Government (General) Regulation 2021. If your approval doesn’t state an interval, ask your council’s environmental health team before you sign a service agreement.

On everything else the certificate is firm:

• A service contract of at least 12 months with a service agent.
• The agent must be trained in servicing these systems and employed or authorised by the manufacturer, and must use parts that meet the specification.
• A completed NSW Health service report goes to council immediately after every service.
• The owner may not service the system unless they are an authorised agent of the manufacturer.

Each visit checks the chlorinator, pump, blower, alarms, slime on the filter media, sludge return and irrigation area, and tests free chlorine, pH and dissolved oxygen on site. For the old Model 10 NR, the handbook tied the warranty to servicing by a technician authorised by AWTS Maintenance Services; long out of warranty, what matters is that your council accepts your agent.

AWTS servicing in our area runs $90 to $150 a visit, and our AWTS servicing cost guide adds up the full year. What a visit includes is on our AWTS servicing page. Before signing with anyone for an Envirocycle, ask them to confirm they’re authorised for that brand.

Common Envirocycle problems and what to check first

Envirocycle’s FAQ and the Model 10 NR handbook describe the same short list of faults.

Low air alarm. The blower isn’t delivering enough air. Envirocycle says to check the blower on top of the tank is running and check its circuit breaker. If it has tripped, reset it once only. If it trips again or the blower still won’t run, call your service agent. The aeration stage depends on that air, so don’t leave it for the next scheduled visit.

High water alarm. Envirocycle’s FAQ describes this alarm as too much air pressure in the system, usually from restricted airflow. Its checks: make sure the blower is running normally, look along the air line for kinks or blockages, and make sure valves are open. If the alarm continues, turn the system off and call. The Oxyfix has 1,000 litres of emergency storage, so cut water use while you wait: no washing loads, short showers.

Sprinklers not working, no alarm. Check the irrigation filter and lines for blockages and straighten any kinked hose. If that doesn’t fix it, the pump may have failed.

Alarm after a power cut. The handbook says a power cut or surge can trip the Envirocycle circuit breaker in the house switchboard, and the alarm can take up to 12 hours to clear. If it hasn’t cleared by then, look for a tripped breaker labelled “Envirocycle” or similar and reset it. If the breaker won’t stay up, stop resetting it and call your agent; any electrical repair has to be done by a licensed electrician.

Foaming or odour. The handbook blames foaming on too much detergent or too many washes in a day. For odour it lists a new system still maturing, too much water at once, heavy use of chemicals and disinfectants, a badly built vent, or overloading.

Water around the electrics. The handbook says water getting into the control box isn’t covered by warranty, and it warns that insurers won’t pay for blower damage caused by letting rainwater collect around the unit. Channel runoff away from the lid and electric box, especially on Hunter River and Williams River floodplain blocks.

For any brand’s beeping panel, see why your AWTS alarm is beeping. An active high-water alarm or sewage backing up into the house gets a same-day or next-morning vacuum truck response from us.

Parts, air pumps and what repairs cost

The Oxyfix certificate lets individual mechanical and electrical parts, such as pumps and controllers, be swapped for alternatives that meet the accredited specification, but it bans permanent changes to the design, including the disinfection unit. So a failed RLB80T can be replaced with another blower that meets the accredited specification, but the process itself stays as accredited.

The certificate sets an expected service life of 5 years for mechanical and electrical parts and 15 years for everything else. On a unit older than that, budget for replacing an original blower, pump or controller.

Our price ranges for the jobs that come up on Envirocycle and other AWTS units:

All electrical work on the system must be done by a licensed electrician; the certificate requires it. We don’t quote Envirocycle’s own prices for parts or new systems, so ask the manufacturer for those.

The primary chamber needs desludging every few years like any septic tank. The Model 10 NR handbook says that’s the owner’s job and any approved operator can do it. Tank waste we remove is transported and disposed of under NSW EPA waste rules at a licensed treatment facility, and a disposal docket is provided for every load. Keep it for your council file.

On “Envirocycle septic system cost” for a new install, we can only give the general range: a complete new AWTS of any brand typically runs $15,000 to $25,000 or more. That work is carried out by licensed plumbing and drainage contractors we work with; their NSW licence number appears on every quote.

Buying a property with an old Envirocycle

An old Envirocycle isn’t a reason to walk away. It is a reason to ask these questions before exchange:

1. Which model is it? Check the plate on the tank or control box. An Oxyfix has a current certificate; a Model 10 NR or older unit is off the register.
2. What does the approval to operate say? Look for the service interval. Our guide to buying a property with a septic system covers what happens to the approval after settlement, council by council.
3. When was the last service? Ask for recent service reports. A long gap means nobody has checked the blower, pump or alarms in that time.
4. On a UV unit, does the lamp work? Both panel lights on together meant a UV fault.
5. How old are the blower, pump and controller? Against a five-year expected life, anything original on a 2000s unit is due.
6. How does the irrigation area look? Surface ponding, runoff and excess plant growth are all on the council’s service report form.

A building and pest inspection won’t open the tank. Our pre-purchase septic inspection covers the tank, pipework and irrigation area with a written report, at $250 to $500. To talk it through first, call 0468 278 123 and tell us the model on the plate.

Frequently Asked Questions

How does an Envirocycle work?

An Envirocycle settles and digests solids in a primary chamber, then pumps air into a second chamber where aerobic bacteria break down what is left. The water settles again in a clarifier, is disinfected, and is pumped to an approved irrigation area. The current Oxyfix uses chlorine tablets; older Model 10 NR units used a UV lamp.

Is the Envirocycle Oxyfix accredited in NSW?

Yes. As at 28 September 2026, the NSW Health register lists the Envirocycle Oxyfix AWTS for up to 8 persons under certificate STS-AWTS064, expiring 31 December 2027. Older units such as the Model 10 NR are not on the current register, but an installed one keeps operating under its existing council approval.

How often does an Envirocycle need servicing?

The Oxyfix certificate says four-monthly in clause 3.3 but refers to each three-monthly service in clause 3.5, and the old Model 10 NR handbook set three services a year. The interval that applies to you is the one in your council’s approval to operate. If it isn’t stated, ask your council before signing a service agreement.

Can I service my own Envirocycle?

No. The Oxyfix certificate says the owner must not service the system unless they are an authorised agent of the manufacturer. You can confirm the blower is running, reset a tripped breaker once, and straighten a kinked irrigation hose, but the service and the report to council must come from an authorised agent.

Why is my Envirocycle alarm going off?

The usual causes are a stopped blower or tripped breaker, a restricted air line, a failed or blocked irrigation pump, or a power cut, and on older units a failed UV lamp. Check the blower is running and reset its breaker once only. If the alarm continues, cut water use and call your service agent.

Who can pump out an Envirocycle?

The primary chamber needs desludging every few years like any septic tank, and the Model 10 NR handbook says any approved operator can do it, not only Envirocycle. We desludge AWTS for $450 to $750 and provide a disposal docket for every load.

Sources and further reading

• NSW Health, Aerated wastewater treatment systems (AWTS) register: lists the Envirocycle Oxyfix AWTS for 8 persons, STS-AWTS064, expiring 31/12/2027, under AWTS Maintenance Services Pty Ltd t/a Envirocycle (checked 28 September 2026).
• NSW Health, Certificate of Accreditation STS-AWTS064, Envirocycle Oxyfix AWTS: tank and chamber capacities, blower and pump models, effluent limits, nutrient reduction, service life, servicing interval (clauses 3.3 and 3.5), service agent conditions, part substitution, owner-servicing ban and the council service report form.
• Envirocycle, home page: trading entity, Heatherbrae and Beerwah offices, treatment process description.
• Envirocycle, About Envirocycle: 1982 origin and 1984 Australian Design Award claim.
• Envirocycle, Frequently Asked Questions: high water alarm, low air alarm and irrigation fault checks, reset-once rule.
• Envirocycle, Product Servicing and Maintenance: the manufacturer’s general statement on visit frequency.
• The Envirocycle Handbook 2004 (Model 10 NR owner’s manual; copy hosted by Blackbutt Plumbing): UV disinfection and the earlier use of chlorine, tank size, alarm light codes, four-monthly servicing, 16-month air pump parts, warranty and service life, power-cut reset, desludging, foaming and odour causes, and blower water damage.