> 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/modeling-basics/node-types/water-transport/breaklink-node.md).

# BreakLink Node

## General Description

The **BreakLink node** can be used to reduce the number of routes in a model. 

For instance, in a model with form (3, 1, 3), i.e. 3 (A, B, C) inputs connected to 3 outputs (D, E, F) via a bottleneck (X), there are 3\*3 routes = 9 routes.

```
A -->\ /--> D
B --> X --> E
C -->/ \--> F
```

If X is a storage, there are only 6 routes: A->X\_o, B->X\_o, C->X\_o and X\_i->D\_o, X\_i->E\_o, X\_i->F\_o.

The BreakLink node is a compound node composed of a [Storage](/waterstrategy/modeling-basics/node-types/water-storage/storage-node.md) with zero volume and a [Link](/waterstrategy/modeling-basics/node-types/water-transport/link-node.md). It can be used in place of a normal Link, but with the benefit that it reduces the number of routes in the model (in the situation described above). The resulting LP is easier to solve. [API Reference](https://pywr.github.io/pywr-docs/master/api/generated/pywr.nodes.BreakLink.html#pywr.nodes.BreakLink).

## Primary Attributes

<table><thead><tr><th width="180.33333333333331">Name</th><th width="318">Description</th><th>Required</th></tr></thead><tbody><tr><td>allocation penalty</td><td>The cost per unit flow via the node</td><td>Optional</td></tr><tr><td>conversion_factor</td><td>The conversion between inflow and outflow for the node</td><td>Optional</td></tr><tr><td>max_flow</td><td>The maximum flow constraint on the node</td><td>Optional</td></tr><tr><td>min_flow</td><td>The minimum flow constraint on the node</td><td>Optional</td></tr><tr><td>prev_flow</td><td>Total flow via this node in the previous timestep</td><td>Optional</td></tr></tbody></table>

## Examples


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://water-strategy.gitbook.io/waterstrategy/modeling-basics/node-types/water-transport/breaklink-node.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.