A basement bathroom, laundry room, or wet bar below the sewer line relies on an ejector pump to push waste up into the main line. A pump that hums but does not run, a basin that fills without draining, or a sour smell nearby usually means a stuck float switch, a jammed impeller, or a vent not clearing air pressure from the tank.
If a fixture backs up, stop using that drain until the pump is checked, since more water into a full basin can push sewage back through the trap. Do not open the basin lid to investigate; sealed lids keep sewer gas out of the house.
An alarm sounding, sewage odor indoors, or a backup reaching the floor drain means it is time to call rather than wait. Smart Pro Plumbers connects Chula Vista, CA households with a plumber who services and replaces ejector pumps, basins, floats, and check valves. Call (844) 898-0295 for a referral.