If i have External Water Storage (Fluid Tanks) attached to the network and at minimum 1 Fluid Drive it will allow me to store infinite numbers of Fluid in the Fluid Drive.
In my Current Test World im using the variants with highest capacity in case this makes a difference.
The moment i disconnect external fluid storage it respects the capacity limit again, wont remove excess fluids but at least it will stop pumping more fluid in to an already full storage.
If any files or a copy of my save is required i can provide those.