Though you can try to install a drop-in sink by under mounting it, it’s not usually recommended. This is because you may find it harder to seal the sides properly and therefore the water will start to spill out over the side of the sink. A gap will be created when you install a drop-in sink this way, and you’ll, therefore, have to find a solution to fill this. So, it’s wiser to select the right type of installation for the area you wish to place your sink in.