Water Supply

How your water gets to you

There is a constant cycle of water being evaporated from lakes and oceans to form clouds which then fall as rain over the land. Rain feeds rivers which return the water back to the ocean. This is known as the "water cycle".

We rely on the water cycle to provide us with the water that is essential for life. Most of Melbourne's water comes from rainfall harvested in forested catchments to the north and east of the city.

Streams from these catchments flow into storage reservoirs including Yan Yean, Maroondah, Upper Yarra and Thomson.

To provide extra storage and ensure supplies are available closer to customers during summer when consumption is higher, water is transferred to seasonal balancing reservoirs such as Greenvale, Sugarloaf, Silvan and Cardinia. These reservoirs do not have catchments of their own. Water flows from seasonal balancing reservoirs to service reservoirs which are located around the suburbs of Melbourne.

The catchments, storages, balancing reservoirs, and transfer pipelines are all owned and operated by Melbourne Water, which supplies bulk water from this system to Yarra Valley Water and Melbourne's other two retail water companies.

Yarra Valley Water owns and operates the distribution network which delivers water to individual customers. The company conducts daily sampling of water at randomly selected customers taps, service reservoirs and other key points in the system to ensure that safe, high quality water is delivered to customers.

On average, two thirds of the water supplied to domestic customers and most of the water supplied to industrial customers ends up being collected by the sewerage system.

Starting with rain

The water that you drink, wash in and water your garden with begins as rain. Unless you have a rainwater tank, this rain probably fell a long way away from your home.

Rain has to be collected from unpolluted rivers and stored in reservoirs for us to have a reliable supply of clean and safe water.

The rain is collected from areas called catchments. Mountains are often found in catchment areas because lots of rain and snow falls on them due to their height and cold temperatures.

For example, the water supplied to the suburbs and towns in the area serviced by Yarra Valley Water falls in the hills to the east of Melbourne. The rainfall in this forested catchment area is between 100 and 140 centimetres a year. This compares with an average rainfall of 65 centimetres a year in Melbourne.

Storing Water

Australia is a very dry continent with low and unreliable rainfall. As a result, there is a need to store water. Water is collected and stored when, as rain or melted snow, it travels down the mountains, in the catchment areas, into creeks and streams and eventually into larger rivers.

By building a dam across these rivers we can create a storage reservoir where we can hold the freshwater for us to use. The Thomson reservoir and Upper Yarra Reservoir are two examples of storage reservoirs.

There are also smaller storage reservoirs, called off-stream storages, in the water supply system. These reservoirs do not have their own catchments and draw water from the other reservoirs or from rivers in other locations.

Water supply and Yarra Valley Water

Each year the volume of water supplied to consumers by Yarra Valley Water is around 170,000 megalitres.

The volume of water supplied varies between a maximum of 1,300 megalitres per day, during peak summer use, and a minimum of 330 megalitres per day in winter.

Storage Reservoir A storage reservoir is used to store the water collected from a catchment area.
Chlorination plant A chlorination plant is a type of treatment plant where small amounts of chemicals containing chlorine are added to purify and disinfect the water.
Fluoridation plant A fluoridation plant is a type of treatment plant where small amounts of chemicals containing fluoride are added to the water.
Standpipe A standpipe is a tall slender steel tank that is full of water and is used to increase the pressure for water supply in high areas.
Elevated tank An elevated tank is a small amount of water stored above ground on a stand. It is used to increase pressures in high areas.
Service reservoir This is an artificial structure made of concrete or steel that stores water for supply in peak demand periods. Service reservoirs are found close to the areas that they supply and are filled with water from a storage reservoir.
Pumping Station A pumping station is a building that houses the equipment used to pump water from a low lying area to a higher area. Pumps are used to fill service reservoirs and to provide higher pressure to customers living on hills.
Pressure reducing valve A pressure reducing valve is a device used to reduce the water pressure in pipes for customers living in lower areas.
Water Mains The final components in the water supply system are the water mains - pipes that carry water underneath most residential streets. There are a number of tapping points along each main. Plumbers attach water pipes that carry water to the taps in your house and garden to these tapping points. Water mains are sometimes found above ground. Here is one at the side of a bridge. A rare event - sometimes a water pipe will burst. This photograph clearly shows the high pressure the water in the mains needs to be kept at to ensure good water flow in the home.	Water mains are sometimes found     above ground.         Here is one at the side of a bridge.
Water Meter Your water meter is used to measure the volume of water used on your property. It is generally located close to the front of your property, often just inside the front fence.