If you live in a house that is not connected to the main sewer, then chances are that your yard contains an on-site sewage management system. If this is the case then you have a special responsibility to ensure that your system is working well. Poorly maintained systems have the potential to significantly affect you and your family’s health, as well as the local environment.

Living with on-site wastewater

If you already have an on-site sewage management management system, this might be a septic tank, AWTS, or “bio-cycle”, you need to know that you are responsible for making sure it is working properly. You also need to have an Approval to Operate for you system. Depending on the risk category of your system Council will also come and inspect your system between every one to five years.

Check out the other information below on how to keep your system and your family healthy.

Building with on-site sewage management

If you are building a new house that wont be connected to the sewer you will need to apply to install your onsite sewage management system. Our Development Control Plan has information on what Council requires for your application and what is and isn’t allowed. There is also a guide for completing a Wastewater Management Plan and the application form.

Buying a property with on-site sewage management

If you are intending to buy a property not connected to sewer you may wish to find out if the property has a legal on-site sewage management system. You or you solicitor can request Council do an inspection of the system and provide the Approval to Operate. If the system is not up to standard you will be advised that it was unsatisfactory on the day of inspection. The owner will then be advised what needs to be done to get it up to standard.

When you have bought the property you need to apply to transfer the Approval to Operate. You have three months to obtain one but should apply within two months. If you do not apply, Council will send out a form when we are advised of the settlement.

Industrial or commercial site not on sewer

Sometimes industrial or commercial operations need more than just a on-site sewage treatment system. This might be a commercial kitchen, wash bay, oil water separator or a number of other processes that make wastewater.

This sort of wastewater cannot be put into a septic tank or domestic type system. Therefore other provisions will need to be made for its disposal. Please talk to Council about your options.

Council's role

On-site sewage management facilities which are not operating correctly have the potential to create environmental disasters. In recognising this potential, the NSW government has enacted legislation that requires approval not only for the installation of systems, but for their continued operation.

Council’s On-site Sewage Management Strategy (OSMS) details the way in which this environmental issue will be dealt with. The legislation requires systems to be approved by Council before installation and operation of the system.

In 2003 a Shire-wide audit was conducted. Many systems were found to be in less than satisfactory condition. As owners brought their systems up to standard, an Approval to Operate was inferred on the system. These Approvals to Operate are valid for five years and many are due for renewal.

Council is undertaking another Audit throughout 2009 to ensure Council’s records are up to date and Approvals to Operate are current.

When it goes wrong!

If effluent is not being effectively absorbed into the soil, it can temporarily pond on the surface where it is accessible to children and pets, putting them into contact with potentially harmful bacteria and viruses. Rainwater run-off from effluent-saturated areas can reach waterways, carrying the contamination downstream to other users and increasing the nutrient loading. Hence effective monitoring of domestic sewage management treatment systems is vital to community and environmental health.

Muswellbrook Shire Council is in the process of implementing an Approval to Operate procedure for the Shire. This will involve regular inspections of on-site sewage management treatment systems to ensure the protection of community and environmental health.

Do’s and don’ts


  •  Minimise water use in your household.
  •  Select cleaning chemicals and detergents which are gentle on your sewage management treatment system and disposal area.
  •  Minimise the use of antibacterial chemicals and bleaches, which can kill off the bacteria treating your wastewater. Please be aware that antibiotics may reduce the effectiveness of your wastewater treatment system.
  •  Complete regular maintenance checks on your sewage management treatment system. Whether it’s an AWTS or a septic it will still require maintenance. Septic tanks may require desludging every 3 – 5 years to prevent solids clogging the absorption area. AWTS require servicing by a qualified technician every 3 months to ensure everything is working correctly and to ensure adequate disinfection.
  •  Keep a site plan indicating the location of your sewage management treatment system and disposal area.
  •  Keep records of installation, pumping, inspections and other maintenance.
  •  Install an outlet filter to your wastewater treatment system. These are available for septic tanks to protect your absorption area from suspended solids.


  •  Put fats and oils down the sink as they cause blockages when they solidify.
  •  Put foreign materials such as sanitary napkins or other hygiene products, condoms or nappies into the system. These will not break down and will cause on-going problems with blockages.
  •  Switch off power to AWTS. These require a constant power supply to operate effectively.
  •  Drive over the disposal area or erect any structures or paths.
  •  Plant large trees to shade the disposal area as sunlight aids in the evaporation and transpiration of effluent.
  •  Use large amounts of bleach, antibacterial products or chemical cleaning products.
  •  Go all-out and wash everything all at one time! Your wastewater treatment system is designed and has grown to treat a constant flow of wastewater throughout the week. When excess wastewater is put through the system it may not be treated adequately.
  •  Ignore the maintenance requirements of your wastewater treatment system!

Will Council be inspecting my septic tank/on-site sewage management system?

The On-site Sewage Management Strategy outlines a range of risk categories. For any given system the highest risk category for the range of issues will determine the risk category of the system.

The risk categories are high, medium and low risk. High risk systems are likely to be inspected by Council every year while medium risk systems will be inspected every 3 years and low risk, 5 years.

Council may also undertake an inspection if information is requested by a potential purchaser or a complaint is made.

Council inspection will incur an inspection fee as set out in the current Schedule of Fees and Charges.

If I have a septic tank will this need to be replaced by a newer environmentally friendly system?

Many people are concerned that when Council inspects their property that they will have to spend thousands of dollars upgrading their system to a newer environmentally friendly system. This however will not be the case. When Council inspects your system, whatever type of system that it is, if it is found to be in good working order then no upgrade will be necessary. If your septic system or other system is found to have problems you will only need to repair it so that it is working efficiently.

What do I need to do when applying for approval from Council?

There are essentially two types of approvals required for on-site wastewater facilitates. These are approval to install or modify and an approval to operate.

Approval to Install or Modify

You will need to complete and return an application to modify and or operate wastewater treatment system form PART B. An application fee of will include a preliminary inspection and the approval to operate for the first five years.

When lodging your application with Council you need to ensure that the following information is included:

  • An On-site Wastewater Management Plan
  • Details about the dwelling that the systems will serve
  • The site and soil where it will be installed
  • The type of system you plan to install
  • The relevant NSW Health accreditation. NSW Health Waste Water website has all the current accredited systems. The certificate for the proposed system should be supplied and read in full
  • Details of the installer (only persons with the appropriate license from Department of Fair Trading are permitted to install systems)
  • The method of waste water disposal
  • A site map

On-site Sewage Management System Supplementary Information - Part B


Approval to Operate

Upon installation a further inspection will be required to allow for the issuing of the Permit to Operate; a fee will be incurred.

Application for an Approval to Operate requires the Application to operate wastewater treatment system form PART A. Council may request further information to ensure our records are complete and up to date. Information may include house plans and Works and Executed Drawings (to show where the pipes, tanks and disposal area are).

Council strongly advises that applicants seek the assistance of a suitable qualified person with experience with the Environmental and Health Protection Guidelines - On-site sewage management for single households from the Office of Local Government and the standard AS/NZS 1547:2000 On-site domestic wastewater management.


Application for Approval to Install, Modify or Operate an On-site Sewage Management System - Part A


Decommissioning Your Septic System

There are two options available to ensure the safe decommissioning of your on-site sewage management system.

Option 1: Decommissioning septic tanks

This procedure ensures redundant tanks do not cause future public health, safety or environmental problems.

  • Have all effluent and sludge removed from redundant septic tanks by an approved contractor, utilising approved tanker vehicles and approved dump sites.
  • Once tanks are pumped out treat them with agricultural lime to disinfect and neutralise the tanks.
  • Following the lime treatment, make holes adequate for drainage purposes at the bottom of tanks.
  • Break down the concrete lids and a portion of the tank walls to ground level or lower.
  • Fill tanks with solid, non putrescible fill with the ground surface being made good. Fill material may settle over time, requiring more fill.

Option 2: Re-use septic tanks as a storm water storage and irrigation tank

When existing premises are connected to the sewer most redundant septic tanks can be used on-site as storm water storage and irrigations tanks. These converted tanks will be for non-drinking, or non potable uses only.

To ensure that redundant tanks do not cause any future public health or environmental problems, and meet the Department of Health guidelines Council will undertake an audit of the tank conversion.

Refer to Council's adopted fees and charges for the Inspection of On-site Sewer Management fee.


  • Submit to Council an audit application for the reuse of wastewater tanks for water storage purposes.
  • Have all effluent and sludge removed from redundant septic tanks by an approved contractor, utilising approved tanker vehicles and approved dump sites.
  • The tank sides, lid, baffle (if fitted and square junctions) should be hosed down with water as the waste is being removed.
  • Tanks should then be refilled with water and disinfected to a minimum concentrations of 5mg/L of free residual chlorine (refer Table 1).
    Mix the disinfectant in a plastic bucket - in the open air before adding it to the tank.
    Mix it as thoroughly as possible with the tank water and allow it to stand for a minimum of 30 minutes.
    Allow the chlorine to dissipate naturally. Chlorine is readily available from most pool shops.

    Table 1
    Type of ChlorineConcentration of Chlorine RequiredVolume/Weight of Chlorine required per 1000 Litres of Water
    Sodium Hypochlorite (Liquid - 12.5% available chlorine) 5mg/L 40 millilitres
    Calcium Hypochlorite (Granulated - 75% available chlorine) 5 mg/L 7 grams
  • Inlets and outlets may be sealed to utilise additional storage volume. Pumps and other fittings may then be installed and connected to an irrigation system as required.
  • Mosquito proof the tanks and fit with a suitable strainer to prevent coarse materials from getting in.
  • Clearly mark tanks with adequate signage stating “Water unfit for human consumption”.
  • Non-standard water pipe fittings must also be used for the irrigation system. Avoid connections or processes which may contaminate potable water supplies.
  • Direct any overflow to a storm water discharge point or a storm water device constructed in accordance with Council requirements.
  • Call Council's Environmental Health Section on 6549 3700 to arrange for an inspection of your system conversion. Following this inspection Council will advise on the suitability of the conversion in accordance with the department of health guidelines.

CAUTION Care should be taken when using Lime and Solid or Liquid Chlorine. It is recommended that appropriate precautionary steps be taken such as using personal protective equipment (skin protection, eye protection and respiratory protection). A copy of the Material Safety Data Sheet (MSDS) for chlorine should be on hand. It is recommended that only properly qualifi ed persons should be employed to perform any procedures using chemicals.

NSW Government Health Advisory Note 3 - Destruction, Removal or Reuse of Septic Tanks, Collection Wells, Aerated Wastewater Treatment Systems (AWTS) and other Sewage Management Facilities (SMF)


Have the Operational Fee removed from your rates notice

Advice Council when your property has been connected to sewer and the tank has been decommissioned. Council will then remove the operational fee from your rates.


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