Dreame X40 Ultra

It empties into a 3.2 L bag and holds 4.5 L of clean and 4 L of dirty water, so most homes go weeks between refills, and the dock cleans its own base.

The robot is 3.8 inches tall, so it slides under most sofas and cabinets, though very low furniture may be tight.

It clears obstacles up to 22 mm, so it handles standard door sills but may stop at taller thresholds.

Yes. The dock automatically dispenses detergent when washing the mop and refills the robot from a 4.5 L clean tank.