communal tap; shared water faucet
Refers to a water tap shared by multiple households or residents, often in older apartment buildings or communal living areas.
Since this apartment only has a communal tap, the water bill is included in the rent.
Compound of 共同 (shared, communal) and 栓 (tap, faucet). The exact historical derivation is uncertain, but the word is straightforwardly formed from these components.