The more you know!

https://memory-alpha.fandom.com/wiki/Bathroom

The head was visible in a few episodes, but while the doorway was initially labeled "CONFERENCE" in "Gambit, Part II", it was relabelled "HEAD" by "Emergence". In addition, in episodes throughout the seventh season, multiple crew members can be seen simultaneously entering the bridge via the head. It is unclear how many toilets are available for use in the head on the main bridge.