The water sector's greenhouse gas emissions

Direct, or ‘scope 1’, emissions are greenhouse gas emissions released into the atmosphere as a direct result of the processes or activities owned or controlled by the water corporation. In essence, these are the emissions produced by activities on-site, or under your direct control.

Whether a water corporation emits more direct or indirect emissions depends on its functions. Most of the water sector’s direct emissions result from the on-site treatment of wastewater. Another example is the greenhouse gas emissions which result from the use of a vehicle which belongs to the water corporation.

Photo: Melbourne’s Western Treatment Plant (credit: Melbourne Water)

After you flush your toilet or take a shower, the water used can be recycled for non-drinking purposes. Through a treatment process, the water is returned to a safe standard. It can then be returned to the environment or used to water your local sports field or park. This process of recycling water can result in the release of a large amount of greenhouse gases.

As part of the wastewater treatment process, friendly bacteria work to break down organic material and remove nutrients. As they do this, and depending on the type of bacteria, they produce either methane gas or nitrous oxide. Both are strong greenhouse gases.

Many water corporations capture and burn these 'biogases' to generate electricity.

For example, Melbourne Water generate enough electricity from biogas at its Western Treatment Plant to meet nearly all its electricity needs. While it is not always technically possible or cost-effective to capture all the gases from wastewater treatment across the state, more and more Victorian water corporations are capturing and re-using these biogases.

Photo: A Wastewater Treatment Facility (Credit: Gippsland Water)

Indirect, or ‘scope 2’ emissions are the greenhouse gas emissions released into the atmosphere as a result of the indirect consumption of energy by the water corporation. In essence, these are the emissions which result off-site, or by another entity, due to your actions or activities.

Whether a water corporation emits more direct or indirect emissions depends on its functions. Most of the water sector’s indirect emissions result from the use of electricity generated from the burning of fossil fuels, such as brown coal.

It can take a lot of electricity to treat drinking water and move it around the state to where it is needed most. A large amount of electricity is also needed to return sewage and wastewater to a safe standard. Once this is done, the water can be released into the environment or used for non-drinking uses - like the irrigation of your local sports field or park.

If the electricity used to treat or move this water is generated by burning a non-renewable resource such as coal, it can result in a lot of greenhouse gas emissions being released into the atmosphere.

When households, industry, and businesses use water, they are also using energy. When that energy is generated from non-renewable sources, such as fossil fuels, this results in greenhouse gases being emitted into the atmosphere.

In fact, it’s likely that the total emissions generated by Victorians through their water use is much higher than the emissions generated by the water sector to deliver and treat water. This represents a real opportunity for the Victorian water sector and Victorians to take real climate change action to reduce their emissions by focusing on how they heat, and use, water.

By using renewable energy to power your home, fixing that leaky tap, or installing a solar hot water system, rainwater tank, or more efficient showerhead or toilet, you are doing your bit to tackle climate change, save water, and even save money too.