**EDITED**
From what I understand, UP notoriously had "bad water". That could have been anything from high suspended solids to high calcium content. Chemicals are typically added to encourage precipitation of these solids aka "mud". The solids end up on the bottom of the boiler. They (most) flushed out with the bottom blow.
The Wilson Blowdown Separator centrifugally separated the "mud" from the water. Going out on a limb here, I would expect that this device would be more efficient use of water.
I have a few questions:
Does UP use municipal potable water? Perhaps the water used today is inherently "better".
Is there a Zeolite water softener anywhere in the system?
Do UP boilers get an intensive wash-down after each excursion?
