There are little nubbies (feet) on the bottom which keep the mat just a smidge off the sink floor, so that water can pass through, around, and down the drain. When I'm done with dishes, I just pick these up, rinse them off, and place them back down. I wipe them with soapy water occasionally, and spray with a disinfectant when needed.
Rubbermaid Rowekamp 1G1706BLA Sink Mat Sm Black 2-Pack