Possibly, as you put your mouth directly on the same part of the
equipment as everyone's hands would go. You may be more
careful with a cup, since from childhood we are aware of drinking from cups and the hazards of sharing. One
would more likely hold a cup by the handle not the lip.
A pump type filter would somewhat more isolate germs carried
by the hands.

Sharing a filter or cup of any kind may actually put one in
more hazard of getting Giardia than drinking straight from
some sources.


Wash your hands in any case.