Ed Huntress fired this volley in
:

We're miscommunicating. The pressure can only drop an addition 0.4 psi
from the pressure with fully-water-saturated "vacuum." That's all the
"overshoot" that's physically possible.

Ok... I understand that is all the overshoot possible, but the absolute
pressure within that vertical pipe can be drawn down by the falling water
TO 0.4 psi (at 'room temperature' theoretically). That's pretty close to
14-1/4 psi of vacuum relative to atmospheric.

LLoyd