Our emissions

Our emissions

Delivering safe water and treating wastewater takes energy – and energy produces emissions. 

We measure, model and manage our greenhouse gas emissions across all major operational sources. These emissions are reported in tonnes of carbon dioxide equivalent (tCO₂-e), allowing us to compare methane, nitrous oxide and carbon dioxide on a common basis using their global warming potentials. 

From 1 July 2025, all electricity used across our operations is matched with renewable energy generation. That means our grid electricity use is offset by wind, solar and hydro generation through power purchase agreements and renewable energy certificate retirement. 

With electricity decarbonised, our focus now turns to where emissions are harder to eliminate – biological treatment processes and operational fuels. 

Annual emissions

We report our emissions in accordance with the Greenhouse Gas Protocol and Australia’s National Greenhouse and Energy Reporting framework.

In 2024-25 

• Gross Scope 1 and 2 emissions were recorded across water treatment, sewage recycling and transport.
• 29,420 Large-scale Generation Certificates (LGCs) were surrendered to offset our Scope 2 emissions. 
• Net Scope 1 and 2 emissions were 13,454 tCO₂-e, representing a 45% reduction from our 2016 baseline. 

Gross emissions show what we physically generate. Net emissions show the remaining footprint after renewable energy certificate retirement. 

Both matter. 

With Scope 2 emissions addressed through renewable electricity, our emissions profile has fundamentally shifted. 

Where our emissions come from

Now that electricity is matched with renewables, most of our remaining emissions come from: 
 

• Methane (CH₄) produced during wastewater treatment 
• Nitrous oxide (N₂O) formed during biological nitrogen removal 
• Fuel combustion in vehicle and equipment 

Methane has a global warming potential 28 times that of carbon dioxide over 100 years. Nitrous oxide is 265 times more potent. 

Even small releases can have an outsized climate impact.

We’re investing in direct emissions monitoring at Mt Martha and Lang Lang Water Recycling Plants – installing sensors to measure methane and nitrous oxide more accurately, rather than relying solely on emission factors. 

Emissions trajectory

As Melbourne grows, so does the volume of water we treat. That means electricity demand and biological treatment activity increase. 

Our strategy is not only to reduce absolute emissions, but to reduce emissions intensity – lowering greenhouse gases per unit of water supplied and wastewater treated.  

We are doing this by: 

• Optimising energy-intensive assets 
• Increasing biogas utilisation 
• Expanding on-site solar generation 

Where residual emissions remain after reduction efforts, Australian Carbon Credit Units (ACCUs) may be used as a transitional measure under schemes administered by the Clean Energy Regulator.  

Our target is net-zero Scope 1 and Scope 2 emissions by 2030. 

Engineering the carbon curve 

Delivering essential water services means operating large-scale infrastructure every day regardless of weather, demand or population growth. 

Our challenge is to keep that infrastructure reliable while steadily lowering its carbon intensity. 

That means: 

• Designing future assets with lower embodied emissions 
• Operating existing plants more efficiently 
• Integrating renewable energy into core operations 
• Embedding carbon performance into long-term planning 

Net zero is not a single milestone. It is a shift in how we design, invest and operate over decades. 

Related information

If this isn’t what you were looking for, see the following links for more information:

• Climate change
• Climate mitigation
• Reaching net zero together
• Climate adaption