What Is An Undermount Sink?

An undermount sink is a sink installed or mounted underneath a countertop. Undermount sinks eliminate the ridge between the counter and the sink edge, creating a smooth line on the kitchen counter. This smooth transition from the counter into the sink makes cleaning a kitchen or bathroom counter easy-peasey.

And, with no lip around the sink taking up room, an undermount sink allows a little more counter space than an overmount sink.


When installing an undermount sink, the sink is supported by something other than the counter top. A sink is very heavy, especially when filled with water. Therefore, an undermount sink must be properly and securely installed to ensure it stays in place.

Because undermount sinks are heavy, they are usually installed under granite or marble counter tops. These materials are often associated with designer or higher value kitchens and baths.

In contrast, the weight of an overmount, or drop-in sink, is supported by the countertop on all sides. Countertops made of laminate and tile usually accompany an overmount sink as these materials aren’t strong enough to support an undermount sink.

There are different types of undermount sinks, based on the spacing between where the sink meets the countertop. Search for undermount sink images to see what you prefer and weigh the pros and cons of each. Visit a showroom to see how they look.

Undermount Tips

Since it’s so easy to wipe everything on the counter into the undermount sink, keep a wire strainer in the drain to catch any debris swept into the sink.

Another undermount tip: The area between the sink and the counter is sealed with silicone caulking. Clean this area regularly as it is prone to develop mold if left unattended. An old toothbrush is a great cleaning tool.

Call Raymark Plumbing & Sewer at (206) 440-9077 for all of your plumbing and sewer needs. We install drop-in (over mount) sinks and we recommend a professional countertop installer for undermount sinks.

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