Overflow tubes are used in sinks and toilets to help keep water where it’s supposed to be without making a mess. With an overflow tube in place you don’t have to worry about your bar or back line sink overflowing and spilling onto the floor. These convenient little tubes fit inside your sink’s drain, and the top of the tube sits a little lower than the sink lip. When water reaches the top of the tube it starts draining instead of continuing to fill the sink and overflowing. Find the right size, and be sure your overflow tubes are in place if you plan to leave a sink unattended for more than a few minutes.