The most under-utilized storage space in any bathroom is the back of the door. Small home expert Emma Healey ... Store them under the sink, if there’s room, or in the bedroom or linen closet ...

Sink manufacturers offer multiple bathroom sizes ... sizes for top-mount and undermount sinks. Small: From 15 to 20 inches long and nine to 12 inches wide, with a depth between 5-3/4-in.