From Combine OverWiki, the original Half-Life wiki and Portal wiki
The Healing Chamber, also known as the Healing Station and the Healing Cubicle, is an upright healing device seen on Xen. It is similar in appearance and functionality to a shower.
The Healing Chamber is only seen occasionally, usually in hidden areas in the mines during the Half-Life chapter Interloper. It is used by the Vortigaunts working there to heal themselves of possible injuries. Any Vortigaunt damaged by the player will run to the nearest Healing Chamber to restore its health. It appears to use the same healing water as that of the Healing Pool, healing the same amount of player damage per second, and with a seemingly limitless supply of healing power as well, but here it is suspended in midair.