Biosolids are nutrient-rich solids created during the treatment of wastewater.

Wastewater from homes and businesses flows through sewerage networks to GWMWater’s wastewater treatment plants. During treatment, solids are separated from the water and broken down into a stable material known as biosolids. These biosolids are then removed, dried and stored ready for safe reuse.

Biosolids mainly consist of:

• Inactive, naturally occurring microorganisms
• Small amounts of sand and grit
• Other harmless materials removed during treatment.

The quality of biosolids depends on what enters the sewerage system and how the wastewater is treated.

Before any reuse, biosolids are carefully tested to check they meet strict safety standards.

This diagram shows how wastewater is treated and how biosolids are produced during the process.

Biosolids are managed under strict environmental and public health regulations. This helps ensure they are safe for reuse and do not harm people, land or waterways.

All biosolids reuse activities involve regular testing and oversight to protect the environment and our communities.

Landfilling biosolids is not considered acceptable and is only used as a last resort.

Once tested and approved, biosolids can be reused in ways that benefit both the environment and the community.

We follow the waste hierarchy when managing biosolids:

Avoid → Reuse → Recycle → Dispose

Biosolids may be used for:

• Improving soils in agriculture, gardens and parks
• Supporting crops such as cereals, vines, olives and pasture
• Land rehabilitation and landscaping
• Forestry applications
• Composting and topsoil production
• Energy recovery and fuel substitution (such as cement kilns)
• Lower-grade construction materials, including road base
• Emerging technologies being explored across industry, including biofuels, oil extraction, glass roducts.

Biosolids are used to boost soil and crop performance.

Our biosolids are available to GWMWater customers to 'take and use' for free. If you’re interested in using biosolids on your property, we can help you understand your options.

We can provide advice on:

• Whether biosolids are suitable for your land
• Availability and storage locations
• Handling and management requirements
• Any associated costs.

Please contact our Program Lead-Wastewater Quality Management on 1300 659 961 or find out more here.

In Victoria, the use of recycled water is regulated by the Environment Protection Authority (EPA) Victoria and must comply with established guidelines. These are designed to work alongside the Australian Guidelines for Water Recycling, which serve as the national reference for the safe supply, use, and management of recycled water schemes.

The guidelines outline the minimum water quality treatment objectives required for different classes of recycled water. GWMWater supplies Class C recycled water, which meets the following standards:

- < 1000 E. coli organisms/100 mL 

- < 20 mg/L Biochemical Oxygen Demand (BOD) 

- < 30 mg/L Suspended Solids (SS) 

- pH range: 6–9

Class C recycled water is suitable for a range of non-potable applicationsand can be safely used when managed appropriately.

Approved Uses

Irrigation of:

• Public open spaces with controlled public access e.g. municipal parks, gardens, sport ovals, golf courses, and racecourses. These sites are to be clearly signposted and access managed to avoid contact with recycled water, particularly during and immediately after irrigation when surfaces are not dry.
• Human food crops which are cooked/processed before consumption such as vineyards and olive plantations.
• Pastures for beef cattle, sheep, horses and goats grazing
• Non-food crops, woodlots, turf, flowers, etc.
• Dust suppression
• Industrial wash-down (non-food contact surfaces)

Non-Approved Uses

• Drinking, including livestock
• Uses inside the home
• Cooking
• Personal hygiene (e.g. showers, handwashing, etc.)
• Filling swimming pools or spas
• Swimming, bathing, or wash-down water
• Irrigation of edible crops consumed raw
• Irrigating public open space with unrestricted access
• Irrigating pasture for dairy cattle grazing/fodder

To ensure safety and compliance with EPA Victoria regulations, access to sites using Class C recycled water must be restricted as follows:

1. Grains refer to the dry, harvested grain – not grain crop residue with should be treated as direct grazing or harvested fodder.
2. Human food should not be directly exposed to recycled water and should be cooked or processed be before consuming.
3. Helminth control is 25 days of lagoon detention or an equivalent filtration process such as sand or membrane filtration.

To ensure safe and responsible use of Class C recycled water, the following controls must be applied to all irrigated crops:

Source: Publication 1911-Technical information for the Victorian guideline for water recycling

Reach out to our Recycled Water Systems Officer on 1300 659 961 during business hours or email This email address is being protected from spambots. You need JavaScript enabled to view it.