I set bottle emptier to empty water. Then my colony "discovered" polluted water, and they started emptying polluted with THE SAME bottle emptier. I never set polluted water it just AUTOCHECKS UPON DISCOVERY? Instant Ragequit mode.

The issue here is that the game doesn't distinguish between "this category is enabled" and "every currently discovered resource in this category is enabled". If you do the latter — say, when you only "know" about Water and not PH2O — then when the filter options are expanded, the game sees that the category is enabled and that the new fluid is in said category, and enables it.

To prove this: discover H2O and PH2O, enable one of them, then discover a third fluid (salt water, perhaps). Notice that your settings do not change. If, however, you have a different emptier on which both were enabled, it will be automatically enabled for the new fluid.

This same behaviour actually applies to all storage with filters, but it's particularly noticeable with bottle emptiers because everything assignable to them is already in the same category, this being "liquids".

Edited October 14, 2020 by Darael
formatting and expanded example

If you select a single element inside a category that contains only that element, it checks the category as whole. Its a known issue, and it happens also with sand/regolith a lot of times, because untik you discover regolith, sand is the only "filtration medium". 

Yes its annoying. But now you know about it, and you can check it wont happen again. 

This is present for years now, so dont keep your hopes up, this will be fixed.

Guess it could be handy if there was a sort of "Unknown" in each category, that you could uncheck, that would affect all future discoveries.

This is probably more of a design issue than a bug

There is a mod to fix it:

https://steamcommunity.com/sharedfiles/filedetails/?id=1863598374

It is not really much of a problem, once you kow what is going on.