
In the above image, the storage tank was marked for deconstruction before the offshore pump was placed -- yet still ends up being full of water. Furthermore, removing it instantly caused water to go into the adjacent tanks.
In some cases, the fluid may pass through it to other fluid boxes as well:

I believe these are both artifacts of the current fluid handling system: It appears the marked entity does not try to move fluids on its own, but adjacent entities may depending on their location (or build order?)
P.S. Dominik, I'm sorry.