That is correct, Tableau only reads the data. It will not in any way alter your data source.
Thanks for the super quick response. By chance is their any Tableau documentation stating so? I've been looking at the admin guide and others.
The following links go into detail about how Tableau connects to your data and how to interact with it. They do not explicitly say that Tableau is read-only, but it alludes to the fact that Tableau simply connects with the data without actually editing it.
Hope this helps!