The physical supply and use tables (SUT)  for water resources describe the flows of water to and from the environment and the economy. It covers three types of flows:
1. Abstraction of water from the environment into the economy;
2. Flows within the economy;  and
3. Return flows from the economy back to the environment.

The supply table focuses on where the water comes from. The environment provides all water abstracted water to be supplied to the different sectors of the economy, either for own use or for distribution to other economic units. Once water is no longer needed for any economic activity, it is considered supplied back to the environment by the different industries and households.