> For the complete documentation index, see [llms.txt](https://water-strategy.gitbook.io/waterstrategy/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://water-strategy.gitbook.io/waterstrategy/tutorials/creating-a-reservoir-system.md).

# Modelling basin reservoir systems

In this tutorial you will learn how to add new infrastructure to a model including a reservoir, treatment plant and a groundwater source that will supply a demand.

Please note that there are two nodes in WaterStrategy and Pywr that represent reservoirs. The first is a **storage** node and the second is a **reservoir** node.

Both nodes store water. The reservoir node works just like a storage node, however it has built in parameters allowing you to define *evaporation* and *precipitation* directly on the node. To represent *evaporation* and *precipitation* with a storage node, a catchment and output node are required.


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