This final zone handles the construction of the waterfall chart.

![Waterfall Zone.png](B6vNQkqXSk9z)

The Waterfall chart is generated from the [Project Setup](article:13) and creates a chart that is updated in the Waterfall Dashboard.

To achieve that, the reports are first processed to extract only the last run for each configuration. Then, in the [prepare recipe](recipe:compute_waterfall_preparation), the watefall configuration set in the Project Setup is input through the project variables. This configuration is a json containing a list of dictionaries and each of these dictionaries is a configuration that needs to be run. So first, the array is folded to extract all the individual configurations. The configurations are unnnested and finally, using a formula, only the configurations that match the needed ones for the waterfall are kept.

To build the waterfall chart, we need to compute the ECL difference between configurations. This is done in the following [windows recipe](recipe:compute_waterfall_preparation_change). Finally the prepare recipe just fills in the missing cell with the initial ECL value, in the column that was created just before.

The last [python recipe](recipe:compute_gLrPKkLQ) builds the waterfall chart, it saves it as a picture in the final folder and also directly as an insight that is published in the [dashboard](dashboard:hb4XA9U).