Granite is a hard-wearing material that can be used for kitchen worktops and sinks. Its scratch-resistant surface is long-lasting and, although granite sinks can be more expensive than other kitchen surface materials, they can also last longer if treated properly. Like most household items, granite sinks require maintenance, otherwise they might start to leak. If your sink has a leak, this is usually due to a problem with the sealant. You can attempt to fix it without asking for help, however, if the problem persists you might want to consult a professional.
Detect the source of the leak. Look under the sink for the exact location where the water appears. This will help you fix the leak with more accuracy and, if most of the sealant around the sink appears to be intact, you can decide whether to reseal the whole sink or just the affected area.
Remove any dirt from the sealant around the edge of the sink's underside where it meets the granite worktop. Use warm, soapy water or a stronger cleaning product if necessary. Dry the area using a cloth or kitchen towel.
Open the silicon caulk. Place the nozzle where you want to begin resealing. If the caulk comes with a gun, start squeezing the gun gently until a bead of caulk appears on the container's nozzle, otherwise squeeze the end of the tube gently by hand.
Move the caulk container along the edge of the sink and worktop, squeezing continuously to create a line of silicon sealant. Stop when you have applied sealant to the area you want to treat.
Smooth the caulk where necessary. Use the flat edge of a spatula or knife so it creates a seal that completely covers the joint between the sink and the worktop. If there are any gaps, apply more caulk where needed and wait for the silicon to dry. Refer to the packaging for estimated drying times and don't use the sink until the sealant is completely dried and solidified.