About groundwater

Groundwater is water that collects or flows beneath the surface of the soil. It fills the porous spaces in soil, sand, clay, and rocks. Groundwater is accessed using a bore. Groundwater quality varies across Victoria.

Depending on the quality of groundwater, it can be used for a variety of purposes, such as:

drinking water
irrigation of crops (including domestic gardens) and parks
livestock water supply
commercial and industrial purposes
recreational purposes (such as filling swimming pools)
geothermal heating and energy.

In some areas, groundwater is not suitable for human use.

Drinking water and groundwater

Most of Victoria’s drinking water supply is sourced from surface water such as rivers, streams and reservoirs. Mains water is reliable and treated to a level that is safe for human use. Around 50 towns across Victoria are reliant on groundwater for drinking water. In towns where groundwater is used for drinking, the water is treated to a drinking water standard under the requirements of:

the Safe Drinking Water Act 2003, and

the Safe Drinking Wat er Regulations 2015.

In some parts of rural Victoria, private groundwater bores are used as sources of drinking water. Households drinking groundwater should undertake regular management and maintenance of their bores. Households drinking groundwater should undertake regular management and maintenance of their bores. The Department of Health hasguidance on groundwater.

All businesses and community groups that rely on a private water supply for drinking (potable) water must take all reasonable steps to ensure the water is safe for human consumption. Businesses that use water for:

food preparation (including cleaning), or
to supply water to customers (e.g. accommodation / caravan parks etc.),

must, by law, ensure that the water used is potable.

The Department of Health has guidelines that can assist food and accommodation businesses to ensure that their water supply is safe for food preparation and human consumption.

Groundwater contamination

Groundwater contamination is usually the result of poor environmental care and practice. It is identified through a range of activities and programs that EPA regulates. This includes Victoria’s environmental audit system.

Once contaminated, groundwater is very difficult to clean up. It usually becomes a long-term environmental legacy. The General Environmental Duty (GED) requires people undertaking activities that may contaminate groundwater to minimise the risk of this occurring.

Poor practices that have resulted in groundwater contamination include:

poor storage, or disposal, of liquid to land
leaking underground storage tanks.

Over time these contaminants have mixed with the groundwater.

Contamination can occur at the surface when rain mixes with chemicals, which moves through the soil into the groundwater. What causes contamination provides more information about activities that can contaminate groundwater.

It may not be practical to clean up groundwater to the level needed to restore it to its original condition. A good analogy is a sponge dipped in oil and then squeezed out and cleaned. There will still be residual oil present in the sponge. So, groundwater is often cleaned up so far as reasonably practicable. This means that some contamination remains in groundwater. There may be ongoing management needed or restrictions on its use. This contamination requires management under the duty to manage.

Where we become aware of contaminated groundwater we may identify a “Check Your Groundwater” (CYG) area. A CYG area is used to inform the Victorian community about known groundwater quality issues.

Groundwater clean up that involves a discharge to an aquifer (e.g. the injection of remedial chemicals) will need to comply with Permissions under the Environment Protection Regulations 2021.

Check your Groundwater (CYG) Areas

For EPA's guidance on CYG areas refer to

Refer to Victoria Unearthed website.

For a map of all CYG areas identified by EPA, refer to the Victoria Unearthed website

You can also visit Visualising Victoria’s Groundwater to look at IGAs spatially, with other information on groundwater.

Victoria Unearthed

Victoria Unearthed has information about potential and existing contaminated land. It includes data about:

groundwater quality
check your groundwater (CYG) areas
groundwater quality restricted use zones (GQRUZ)
environmental audits
EPA’s priority sites, where we have issued notices relating to contamination
location of ‘Environmental Audit Overlays’. These are tools councils and other planning authorities use to assess land contamination
historical business listings
past and present landfills.

Bore water testing

Bore owners are responsible for making sure the bore water they use is fit for the intended use.

It is important for users of groundwater to understand the risks associated with the intended use of the groundwater supply. Before use, groundwater may need to be disinfected and treated. This is to remove things that may be present, like:

harmful microorganisms,
chemicals,
algal toxins, or
radiological contaminants.

To get your water tested, you should consult:

a suitably qualified environmental consultant or
a NATA (National Association of Testing Authorities) accredited chemical analysis testing laboratory.

For information on engaging an environmental consultant, refer to EPA publication 1702 or speak to your local Water Corporation.