Water catchments

Melbourne’s protected water catchments are the reason why most of our drinking water needs little treatment and tastes great from your tap. Defending and safeguarding these vital assets is one of our most important activities. 

Photograph of a natural weir in one of the catchments

Our catchments include:

  • 56,300 hectares state forest: 
    managed by DELWP
  • 90,800 hectares national park: 
    managed by Melbourne Water and Parks Victoria
  • 7,500 hectares Melbourne Water land
  • 2,100 hectares private land

mw01106-catchment.jpg

 

First, what are protected catchments?

Bottled water is often marketed on the basis of its pristine origins. Melbourne Water sources the majority of Melbourne’s water from remote, forested mountain streams  for a very small fraction of the cost of bottled water.

This is because Melbourne is one of the few cities in the world with protected catchments, which help to produce high-quality water.

Our protected catchments:

  • are located north and east of our city, often in national parks and state forests with limited public access to minimise water quality risks at their source
  • are a fantastic legacy of our city's planners. This approach to managing drinking water quality has a long history in Melbourne, dating back to the late 1800s when it was recognised that public access to water supply catchments — then allowed at the time — was a key contributor to poor drinking water quality
  • help us deliver safe, affordable water and we expect they will continue to be a major source of water for Melbourne and the surrounding region into the future. 

Melbourne Water shares catchment management responsibilities with Parks Victoria and DELWP. Together, we will continue to manage and protect our forested water supply catchments for current and future generations.

So what are open catchments then?

A small amount of our water comes from open catchments, including farmland, rural properties and state forests that are open to activities like camping, four-wheel driving and — in about 0.2% of catchments — timber harvesting from December to April.

Tarago catchment

The Tarago water supply catchment contains land that is privately owned, with a variety of agricultural uses. We have worked with stakeholders, including the Baw Baw Shire Council and the Neerim District Landcare Group, to develop a Tarago Catchment Management Plan.

Mid-Yarra River catchment

The open mid-Yarra River catchment feeds into Sugarloaf Reservoir, where it mixes with water from the protected Maroondah catchment before being treated at the Winneke Treatment Plant.

Water from open catchments is fully treated before it is supplied to you, so it meets the same quality requirements as water from protected catchments. Water from Sugarloaf and Tarago reservoirs is more costly to supply than water from our forested water supply catchments.

If it rains, do our reservoirs 'catch' it?

Answer: In short, not all of it. 

To start with, some of the rain that falls on Melbourne's water catchments is used by vegetation, evaporated into the atmosphere and stored in the soil as groundwater.

Only around 30% to 50% of the rain that falls on our catchments each year ends up in waterways.

This changes from season to season depending on how wet the soil in the catchment is. For example, only about 10% of rainfall during summer turns into runoff because the dry soil acts like a sponge, soaking up the rain before it can flow into streams. 

Watch this video to find out more about 'the sponge effect':

How we defend our catchments

We invest a lot of effort protecting our catchments from the following threats to our drinking water:

Threat 1: Bushfires

Smoke from fire over Thomson Reservoir
Smoke from fire over Thomson Reservoir in a previous fire season

Bushfires impact the quality and quantity of our water:

  • Ash and sediment washed into reservoirs means they can’t be used for many months
  • Less water enters reservoirs while forests recover — which can take over a century.

We’re often the first to respond to fires in the catchments with our seasonal firefighters, and try to stop them spreading by:

  • grass-cutting more frequently in summer
  • strategic planned burns that reduce the risk of intense bushfires
  • maintaining more than 600 kilometres of fire breaks and 1,860 kilometres of roads for firefighters
  • identifying fires as soon as they start — using a lightning tracker tool, fire towers and firefighter patrols.

Threat 2: Human and animal contamination

We restrict access to our protected catchments to avoid contaminating our drinking water. Security teams perform regular patrols, and serious offences like camping, fishing, motorcycle riding or shooting may be dealt with in court.

To prevent disease, pests like wild dogs, feral cats, deer and foxes must also be controlled. Parks Victoria lead an annual trapping and baiting program.

Erosion

Roads allow firefighters to quickly get to bushfires, but also cause sediment to enter the waterways feeding our reservoirs. To minimise this, we make sure catchment roads are properly maintained and have appropriate drainage.

 

Next: water storage reservoirs

Last updated:
29 March 2020