In the 2018 VAGO Audit – Managing the Environmental Impacts of Domestic Wastewater, Recommendation 7 is to develop a standard risk assessment framework for managing onsite wastewater based on relevant Australian standards, including comprehensive measures to assess land capability, environmental factors and the ongoing performance of systems post-2020.

The risk assessment framework developed jointly by DELWP, DH, EPA and the Onsite Domestic Wastewater Management (ODWM) Steering Committee to implement this recommendation acknowledges that there are several instruments and tools that can be updated to ensure better management of risks associated with the management of onsite wastewater systems. The framework shows:

  • the set of connected instruments/tools that operate together to manage aspects of risk
  • those tools/instruments that include instruction about the way things are or should be done, what you are allowed or are not allowed to do (e.g. legislation)
  • instruction on approaches after considering several possibilities
  • this Risk Assessment Framework aligns with ISO31000:2018.

Section 1: Strategic Context

Onsite wastewater systems (OWS) (treating more than 5,000L/day) are often not used or managed most effectively, both at an individual and regional scale. Many older onsite systems are failing and/or discharging offsite and the scale and cumulative impact of this across Victoria is not known.

The objectives this framework aims to achieve are:

  • protection of human health and enhanced liveability by managing risks posed by OWS
  • prevent the spread of disease by direct exposure/consumption or indirect exposure through the contamination of food, water and the environment
  • prevent adverse effects on amenity, recreational use of the environment
  • maintaining or improving water quality, aquatic ecosystems and terrestrial environments by targeting action towards priority areas
  • effective Government policy, legislation and other management tools to guide local and regional action that reduces threats and maximises improvements to water quality and human health
  • community engagement, empowerment and active involvement in protecting and improving water quality and human health
  • effective and efficient delivery of roles and responsibilities by partners and stakeholders to manage risk

Principles for Onsite Wastewater Management (OWM)

  • Risk-based decision-making and prioritisation that primarily achieves human health and environmental outcomes as well as social and economic outcomes
  • Priorities are set using risk and evidence-based approaches for identification of towns/ areas/sites with public health and environment impacts from wastewater management
  • Community centred approach (communities have a stake in decision making on the level of wastewater services provided)
  • Management tools are up to date and facilitate consistent decision-making that addresses and monitors progress on legacy and future issues
  • Seek innovation in treatment/reuse approaches
  • Focus on the provision of solutions that have the highest net benefit to the community
  • Use an Integrated Water Management approach (collaborative)
  • Equity in addressing the problem (address legacy systems, not just those with a permit).

Section 2: Roles and responsibilities for the management of onsite wastewater

There are many entities/individuals with roles and responsibilities for onsite wastewater management at the state and local level.

Environment Protection Authority

The Environment Protection Authority (EPA) administers the environment protection legislation and is responsible for developing the regulation framework for the construction, installation and alteration of onsite wastewater systems, producing guidance documents for onsite wastewater management, providing advice on and interpretation of the guidance and keeping a web-based list of systems which have a certificate of conformity issued by Conformity Assessment Body in accordance with the relevant Australian Standard. (see

Victorian Building Authority

Victorian Building Authority (VBA) is responsible for regulating Victoria's building industry, including the registering and disciplining of building practitioners and Victoria’s plumbing industry, including registering, licensing and disciplining plumbing practitioners. VBA undertakes inspections, investigations and audits to enforce compliance with relevant regulations, the Plumbing Code of Australia and referenced Australian Standards.

Department of Health

Department of Health (DH) is responsible for administering the Public Health & Wellbeing Act 2008 which aims to protect the health of all Victorians. DH has a role in providing advice on the framework for onsite wastewater systems to minimise the potential impacts on the provision of safe drinking water and public health.


Department of Jobs Precincts and Regions (DJPR) -Local Government Victoria is responsible for overseeing the Local Government Act 2020 and provides business and governance support and advice to the local government sector.


Department of Environment, Land, Water and Planning (DELWP) is responsible for the planning framework for new development, ensuring the VPPs reinforce the importance of managing risks through the planning framework; oversights implementation of the Water Act 1989-sections that provide powers/direction to water corporations associated with sewer connections/provision of services.

Local Government Authorities

Council is responsible for issuing onsite wastewater management system permits (for systems less than 5000 litres per day) with a requirement that sewerage services are provided at the time of sub-division where wastewater cannot be contained within the boundaries of allotment; assessing land development applications to determine the suitability of a site for an onsite wastewater system; assessing onsite wastewater management permit applications; issuing Permits to install/alter and Certificates to Use onsite wastewater systems; ensuring systems are installed in accordance with the conditions on any Planning or septic tank Permit issued for a site and the relevant Australian Standard; ensuring systems are managed in accordance with the septic tank permit, the Code of Practice, the Public Health and Wellbeing Act (2007) and, where applicable, AS/NZS1547 through relevant compliance and enforcement programs; and developing and implementing Domestic Wastewater Management Plans.

Developers and individual landowners

Developers or individual landowners are responsible for engaging a suitably qualified soil science professional to undertake an assessment of the capability of the site, land and development proposal (a land capability assessment) to sustainably contain and manage wastewater on their property. Before installing an onsite wastewater system (treatment unit and land application), a property owner must arrange for a site assessment to be completed by a suitably qualified consultant and apply to Council for a Planning Permit (where required) and permit to install the treatment and disposal/recycling system.
Suitable competent professional contractors can install on or in the ground onsite wastewater systems. Professional service technicians must be suitably trained in the installation, operation and service requirements of the system.

Water Corporations

Water Corporations have a major interest in the correct functioning of onsite wastewater systems under the Water Act 1989, the Water Industry Act 1994 (for Melbourne metropolitan water retailers), the Planning and Environment Act 1987 and the Catchment and Land Protection Act 1994. The key area of concern is failing onsite wastewater systems which may impact water quality in waterways, channels and reservoirs especially in special water supply catchments as this may result in increased health risks to customers and increased operational costs to manage the problems associated with additional treatment of that water. Water Corporations lead the provision of sewerage services and enforcing connection to the sewer mains within the sewerage district.


Manufacturers and importers of onsite wastewater systems who sell and install individual treatment system brands and models in Victoria, must have each system certified as conforming to the relevant Australian Standard by a JAS – ANZ accredited Conformity Assessment Body.

Section 3: Risk Assessment Framework Structure

Public Health

  • Prevent the spread of disease by direct exposure /consumption or indirect exposure through contamination of food, water and the environment
  • Prevent the adverse effect on recreational use


  • Prevent the pollution of waterways, including surface and ground water
  • Prevent reduced amenity & property values
  • Consider climate change impacts and adaptation methods

Social considerations

  • Where managed appropriately wastewater to be seen as a resource- (Shift the paradigm of the social perception of wastewater being seen as a nuisance)
  • Requires active community interest and participation

Economic considerations

  • Considers costs of treatment options, land requirements, construction costs, O&M costs, personnel, energy, equipment, approval and
    compliance costs and affordability of technology.
  • Desired economic growth of towns and relationship with cost benefit of servicing options.

Infrastructure considerations

  • Considers system type, design, and impact such as loss of wildlife habitat/energy required/adjacent property values

State level leadership functions and ODWM risk management tools

Leadership roles and responsibilities for onsite domestic wastewater management at the state level lie primarily with the Environment Protection Authority, DELWP, DH, and VBA. The governance roles performed by these agencies include setting and administering the legislative framework, including articulating strategic objectives for managing risks associated with wastewater management, and providing strategic direction to reviews of the state-scale levers below that can drive better management of risk.

DELWP and EPA will strengthen existing guidance by ensuring consistency with:

  • General Environmental Duty (GED): The GED requires that ‘any person who is engaging in an activity that may give rise to risks of harm to human health or the environment from pollution or waste must minimise those risks, so far as reasonably practicable’. Doing what is reasonably practicable means that proportionate controls to mitigate or minimise the risk of harm are employed.
  • Implementation of the Environment Protection Regulations 2021 provide that: A permit from
    council is required to construct, install or alter an OWMS with a design or actual flow rate of sewage not more than 5000L on any day.
  • EPA publication 1976: Guidance for owners and occupiers of land with an OWMS ≤ 5000 litres on any day (including septic tank systems).
  • EPA publication 1974: Regulating onsite wastewater management systems.

Implementation of the Environment Protection Transition Regulations 2021. The Regulations provide that certain clauses in SEPP (Waters) will be saved for a period of 2 years to allow more time for DELWP and EPA to consult with duty holders and identify the most suitable replacement instrument to address the issues in these clauses. In response to the 2018 VAGO audit, DELWP and EPA will improve the accuracy and comprehensiveness of catchment risk assessment processes by strengthening information in the 3 key existing guidance documents (Figure 1) or their equivalent, in terms of defining:

  • minimum standards of data to inform plan/risk assessment, to understand the physical environment and provide base level of information required to assess existing/future risks
  • minimum risk factors to be considered in any risk assessment: (existing and future risks)
  • minimum standards for analysing risk: standardised risk ratings across all risk assessments for likelihood and consequence.
  • updated treatment options for addressing risk
  • determining effectiveness of controls at modifying this risk

Key guidance documents

MAV Victorian Land Capability Assessment (LCA) framework (2nd Edition 2014)

An LCA is required for most unsewered developments, prior to the development proceeding. It may be also be required to determine whether an existing development can sustainably contain all treated wastewater onsite. As the timing and the level of detail of the assessment can vary this document provides guidance to land capability assessment professionals in undertaking LCAs for a range of development types and provides the framework to assess a site’s suitability to support an onsite wastewater system. Land capability assessments are used by Councils and water corporations.

EPA Code of Practice – onsite wastewater management (Publication 891.4, July 2016)

This code provides standards and guidance to ensure the management of onsite wastewater (up to 5000 L/day), protects public health and the environment and uses our resources efficiently. It has been written to support the onsite wastewater industry, regulators and premise owners design, install and/or manage sustainable sanitation and re-use systems in accordance with environment protection requirements.

MAV Domestic wastewater management plan model 2005

This outlines and explains a model for local government to use when developing a domestic wastewater management plan (DWMP).

Page last updated: 19/05/23