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Water terms explained

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A layer of fractured rock, sand or limestone below the ground that is porous enough to hold groundwater and allow it to flow.


A layer of rock or clay that may hold some groundwater but is not porous enough to allow it to flow significantly.

Bundled and Unbundled

All water entitlements in regulated systems in Victoria are unbundled. This means they are separated into three parts:

  • Water Shares (high and low reliability)
  • A Delivery Share
  • A Water Use Licence

Other diversion licences, groundwater licences and recycled water remain bundled – that is, they are not separated into different parts.


A catchment is an area of land where run-off from rainfall goes into one river system.


An upper limit for the amount of water that can be taken from a waterway, catchment, basin or groundwater area.

Environmental water reserve

The Environmental Water Reserve is the legal term which describes the water set aside by law to meet environmental flows in creeks and rivers.


Groundwater happens when rain seeps into the soil and down into aquifers – nature’s way of storing water under the ground.

Groundwater can vary in yield and quality. It is usually contained in layers of sands, gravels, clays, limestones and other materials above bedrock.

Groundwater is part of the water cycle. It flows into and out of rivers, streams, estuaries and wetlands.

Measuring water volumes

We measure water in litres. Larger volumes of water are described as megalitres (ML) which means one million litres, or gigalitres (GL) which is a thousand million litres.

Regulated and unregulated systems

A regulated water system is one where the flow of the river is controlled through a large dam or weir.

An unregulated system has no large dams or weirs to regulate flow.

Surface water

Surface water is created by rain that falls on river catchments.

It collects and flows into creeks, rivers, dams and estuaries.

Where else can water come from?

Other water sources include:

  • run-off from irrigation areas
  • recycled water
  • stormwater (run-off from urban areas)