This is stupid I know but in all of my playthroughs, I have never been able to discover the East Pump Station, even after entering the building, circling it about a dozen times it wouldn't register as discovered I'm just wondering if anyone else has had this "problem"

Walk right up to the outside wall in between the front steps of the station and the cistern to the south (i.e. to the right if you're facing the station) and you should "discover" it - you'll almost have to touch the wall to do so.

if you're using PC, open console with (~), type 'tcl', the marker should be almost inside the wall