I had some levels of water that I was letting drain by gravity. After awhile the water was on the floor, but very shallow. When I set the microbe musher to make lice loaf, the dupes kept getting 1 kg at a time from the water and delivering it to the musher. Like all of them for a very long time. I think they should try to grab more water from the next tiles before heading back to drop off.
Steps to Reproduce
Have a shallow long pool of water near microbe musher and set to fabricate a food.
This issue has not been confirmed by a developer yet.