if the ceiling is above ground/grade, its not groundwater accumulation.
Is your water main/spigot located near? Im having a hard time picturing the area/home ( since i live in SELA and have NO CLUE about basements lol )
keep in mind, the leak could be 20 ft away- water finds its lowest elevation and then pools. So chances are your ceiling isnt "plumb" ( aka level ) and water from either incoming or outgoing ( shower/bath drain ) could most likely be the culprit. Is the area insulated? ( between ceiling and 1st floor )