Wastewater Information

How is domestic wastewater managed on property (sewerage or onsite)?

Reticulated sewerage is when your domestic wastewater is piped to a central treatment facility. In Baw Baw Shire, South East Water and Gippsland Water provide this service. You are likely to have access to reticulated sewerage if you are in a town and have a property of less than 4,000m² in area.

Even if you live near one of the more developed towns in Baw Baw you may still be in an area (usually on the out skirts of these towns with a larger property size) that is not covered by a reticulated service and will need to treat and dispose of your wastewater on your property.

To determine how much wastewater you produce, your plumber will count the number of bedrooms in the house. They won't use the current number of occupants in the house to size the system because your septic system must be designed to cope with the occupancy potential of your house, to cover things like growing families, new owners etc.

There are a number of different ways to treat your domestic wastewater on site.

Types of systems and their maintenance requirements

Of the many different methods of treating domestic wastewater onsite the main difference is the designed level of treatment, either primary or secondary treatment.

Primary Treatment

Primary treatment standard is achieved by one round of treatment before the effluent is applied to the soil. Waste water goes into a septic tank where the solids settle out and are partially broken down by bacteria that can survive in airless environments.

Primary treatment is generally suited to properties without many constraints (ie. good soil, large property, not near waterways) and lower numbers of septic systems in the area.

Due to their simplistic nature, primary treatment systems usually require less maintenance.

Secondary Treatment

Secondary treatment systems involve two stages. After the septic tank effluent is moved to an aerobic environment that allows a different set of bacteria to further treat the waste.

The higher quality of treated effluent is more suited to distribution on more constrained properties ie. Small property size, poorer soil, high density of septics in a small area, proximity to drinking water supply etc.

Sand filter and aerated wastewater treatment systems are two common methods used in Baw Baw to achieve secondary treatment standard. 

Secondary treatment systems generally require more maintenance. The more advanced aerated treatment systems require 3 monthly servicing due to their highly calibrated nature.

Declared Water Supply Catchments

What are they?

The Victorian State Government declares these areas in order to protect drinking water supply. If you are on town water your water comes from these catchments. As the majority of these catchments in Baw Baw Shire have people living in them (including houses, septic tanks, farms etc.) it is important we manage our source catchments to protect public health.

Human infectious pathogens from septic tanks survive in water and can therefore reach our waterways via water flowing over land and in the soil profile.

Drinking water is treated for pathogens and bacteria but because infection can be caused by the smallest amount of live organisms we need to make sure we are all doing what we can to stop wastewater entering the drinking water supply.  

Gippsland Water have an interactive catchment map on their website that will assist you in finding out if your property is in a catchment.

Please note, the interactive map doesn’t include the Tarwin River catchment that supplies the South Gippsland region.

Click here to learn more about Victorian Declared Water Supply Catchments.

Domestic Wastewater Management Plan


The plan has been developed to help us not only carry out our legislative duty with regard to onsite wastewater management but to also allow us to better identify risk and target our resources to ensure the most optimal outcomes for public health and the environment are achieved.

A key priority of the plan is to raise landowner and community awareness of the impact septic systems can have on public health and the environment.

We are working closely with the Water Corporations in our Shire to protect the quality of drinking water they deliver to our residents.

Property risk ratings and requirements

As part of the Domestic Wastewater Management Plan each property in the Shire has had a desktop assessment of constraints to wastewater treatment, resulting in a risk rating.

Properties in a Declared Water Supply Catchment have a higher risk of negatively impacting public health, it is important wastewater systems in these areas are adequately designed and maintained.

Properties with a risk rating of Medium and above may require a Land Capability Assessment to show that wastewater can be retained on site.

Who should I talk to, what should I ask?

Public Health Department

We can let you know the risk rating for your property and what documentation you will need to submit for your application.

We can’t design the required system for you, this is what your plumber or land capability assessor will do.

Although we can’t recommend contractors, below are a few professionals you may need to speak to and some notes that may help you choose a competent contractor.


A plumber is your first port of call, they will let you know what system is suitable for your house and often they will submit applications to council on your behalf. Some questions that might help you choose a plumber.

  • Are you a registered plumber?
  • What experience in wastewater do you have?
  • Will you complete all council required applications?
  • What are the ongoing maintenance requirements?

Pumpout Contractor

These contractors remove the material that accumulates (sludge) from your system. Keep the receipt and mail to Council as record of desludge.

Your Permit to Use will tell you how often to desludge (clean) your septic tank. As a general rule a septic tank should be inspected and desludged every 3-5 years. 

Land Capability Assessors

A land capability assessor s someone with soil science qualifications and experience, with specific knowledge in soil hydrological and soil chemical processes in relation to domestic wastewater management. They will assess the soil type at your property and will develop design specifications to deal with the specific constraints to wastewater management on your property. 

They will require a description (usually in the form of building plans) of the proposed development so a wastewater system can be designed that meets your needs and complies with public health and environmental regulations. 

Systems Larger than 5,000L a day 

If you require a large system (>5,000L/day), more likely to be a commercial premises as opposed to a domestic dwelling you will need to contact the Victorian Environment Protection Authority.