I know I've seen this referenced in another episode, but in Episode 21
Also because of the events in episodes 19 - 20
(and of course, vise versa...)
But I'll have to look again, because I could have sworn that
Washu explicitly states that she's only taking favors from Pretty Sammy. Sasami storms out of Washu's "Lab" and transforms in the hallway. Then comes back in. It's obvious that Washu clearly knows Sasami is Pretty Sammy.
Also because of the events in episodes 19 - 20
Misao definitely knows Sasami's secret.
(and of course, vise versa...)
But I'll have to look again, because I could have sworn that
Mihoshi also knows.
