The Drawing Center
35 Wooster St, New York, NY
100% positive
Directions: two unisex single-stall bathrooms. downstairs behind the reception desk, there are stairs and an elevator.
Comments: admission into the further-back main part of the gallery is $5, but I believe you could browse their book area (in the reception lobby) for a bit or just come in and ask about information/hours etc, and then ask to use the bathroom, and they wouldn't give you any grief about not paying.