The short answer
Check the Seal First
The most common cause is a broken or missing bead of caulk where the sink rim meets the countertop. Over time, that seal dries, cracks, or pulls away, leaving a gap. Water sitting on the counter then seeps through that gap and drips down the sides of the sink, appearing as a leak from the rim.
To test, dry the rim completely and run water along the counter edge. If you see drips underneath, the seal is the problem. Remove the old caulk with a putty knife, clean the area, and apply a fresh bead of silicone caulk. Let it cure fully before using the sink.
Look at the Sink Clips
Under-mount sinks rely on clips or brackets to hold them tight against the countertop. If a clip loosens or breaks, the sink can drop slightly, creating a gap at the rim. Water then finds that gap and leaks below. You may also hear a slight movement when you press on the sink.
Inspect the clips from inside the cabinet. Tighten any loose screws, but avoid overtightening, which can crack the sink or countertop. If a clip is rusted or missing, replace it with the same type. A plumber can handle this if you are not comfortable working under the sink.
- Dry the rim and countertop completely before testing
- Run water along the edge and watch for drips underneath
- Use a flashlight to inspect the caulk line for cracks
- Press gently on the sink to feel for movement
- Check under the cabinet for water stains or dampness
Consider the Sink Basin
Sometimes the leak is not from the rim seal but from the sink basin itself. A hairline crack in the porcelain or stainless steel near the rim can let water escape. These cracks often start at corners or where heavy pots have dropped. Water then runs down the outside of the basin and looks like a rim leak.
Run water into the sink and watch the underside carefully. If you see a drip coming from a specific point on the basin, that indicates a crack. Small cracks might be patched temporarily with epoxy, but a cracked sink usually needs replacement. Until then, avoid using that area.
Inspect the Countertop Edge
The countertop itself can be the culprit. If the counter is not sealed where it meets the backsplash or the edge is worn, water can run underneath and drip down at the rim. This is more likely with laminate or tile counters where seams are exposed. Check the entire counter perimeter, not just the sink rim.
Look for gaps in the counter seams and reseal them with caulk. Also check the faucet base, as a leak there can run along the counter and appear at the rim. Wipe the counter dry after each use to reduce the amount of water that can seep into small gaps.
When to Call the Pros
If the leak continues after resealing and tightening clips, the problem may be deeper. Water that has soaked into the countertop or cabinet can cause swelling, warping, or mold. You might also notice a musty smell or soft spots in the wood. At that point, it is worth having a professional inspect the area.
Local water damage pros can check for hidden moisture behind the counter and under the sink. They use moisture meters to find the extent of the damage and can help dry out the structure. If you live in Layton, keep your shutoff valve location written down so you can stop the water quickly in an emergency.
- Water stains on the cabinet floor or walls
- A musty odor coming from under the sink
- Soft or spongy wood near the sink base
- The leak returns after you reseal the rim
- Visible mold growth on the counter or cabinet
Water damage does not wait
Water keeps spreading into floors and walls, so it is worth acting early. Calls are answered 24/7.
Call Now (801) 383-0232Frequently asked questions
How do I know if the leak is from the rim or the pipes?
Dry the rim and the pipes completely, then run water. If the dripping comes from the top edge, it is the rim. If it comes from the pipe connections, it is a plumbing leak. Use a flashlight and a mirror to see the exact source.
Can I just put more caulk over the old caulk?
No, you should remove the old caulk first. New caulk will not stick well to old, cracked caulk, and the gap will remain. Clean the area with a scraper and rubbing alcohol, then apply a fresh bead. Let it dry completely before using the sink.
What if the leak is causing damage to the cabinet?
Stop using the sink and dry the area as much as possible. Remove any wet items and place a fan to circulate air. If the cabinet is swollen or mold appears, you may need to replace the damaged wood. Consider calling the pros for a thorough drying and inspection.