Water gets dirty although clean water in Sandbox mode is checked

[Lailantie]

I've played this zoo for at least 50 hours. In Sandbox settings, I have electricity and clean water everywhere and that's how it was. Now I did some terraforming including the large river and bigger bodies of water, and suddenly some water places in the habitats turned so dirty that my animals got sick. The water cleanliness is still checked. Is this a new bug?

 

[Lailantie]

It was another confusing setup. The settings say: Water cleanliness. So I had it checked all the time and my water stayed clean all over my zoo without any equipment for more than 50 hours. Suddenly some waters became dirty. I checked again. Water cleanliness. "If this is DEactivated, the water will remain clean." So I unchecked water cleanliness and the water became clean.

I know they just called it that way because it's the settings if you want auto-clean water or not. But it is so very misleading the way it is worded.