Xiaomi Robot Vacuum S40chat_bubble_outlineFrom real comments

Suction and cleaning power impress most users. Commenters consistently praise the 10,000-15,000Pa suction, noting it pulls up a surprising amount of dust and makes floors feel clean underfoot within days of use. One owner cleared 180 square meters in about 90 minutes using half the battery. It also handles hard fiber carpets well with a boosted suction setting, though soft cloth rugs and runners can tangle it, so several owners simply lift small rugs before each run.

Mopping performance disappoints several buyers. Multiple users say the single included mop pad is thin, gets dirty after just one room, and loses effectiveness quickly, pushing some to buy extra pads and swap them manually between rooms. Others report inconsistent wet mopping between uses, a soaked main roller brush after mop mode, and uncertainty about using disinfectant since soap isn't recommended in the water tank. Hair collecting on the mop was also noted as an issue.

Mapping and hardware reliability are inconsistent. Several owners describe rooms splitting or merging on the map, requiring manual edits, and at least one reported the map distorting entirely after a month of use, losing tracking of the robot's position. Others encountered a torn rubber membrane on the brush holder, a lidar sensor error prompting a return, docking and charging failures, and trouble fitting the mop water tank into the base station.