If you’ve noticed water collecting in the cabinet below your sink or dripping from the plumbing connections, your faucet is leaking under the sink. This type of leak is often hidden, which makes it especially dangerous—it can lead to mold growth, warped cabinets, and costly water damage if not addressed quickly. The good news is that most under-sink faucet leaks are easy to identify and fix with some basic troubleshooting.
Common Causes of a Faucet Dripping Under the Sink
Leaks beneath the sink can come from several different sources. Identifying the exact cause is the first step toward fixing it.
- Loose Supply Line Connections: The hot and cold water supply lines may have loosened over time.
- Worn Supply Hoses: Flexible braided hoses can develop pinhole leaks or cracks.
- Leaky Shut-Off Valves: The valves connecting your faucet to the main water supply may drip.
- Faulty Faucet O-Rings: Internal seals may allow water to escape down into the cabinet.
- Drain Assembly Issues: Sometimes what looks like a faucet leak is actually a leaking drain pipe or P-trap.
How to Diagnose the Leak
Follow these steps to locate the exact source of the dripping:
- Dry the area: Wipe down all plumbing parts under the sink with a towel.
- Turn the faucet on: Run both hot and cold water for a few minutes.
- Observe carefully: Look for fresh water forming on supply lines, valves, or fittings.
- Check the drain: Fill the sink partially, then let it drain. If water appears only then, the leak is in the drain, not the faucet.
Fixes for a Faucet Dripping Under the Sink
1. Tighten Loose Connections
Using an adjustable wrench, gently tighten the nuts that connect supply lines to both the faucet and shut-off valves. Avoid overtightening to prevent damage.
2. Replace Supply Lines
If the hoses are old or cracked, replace them with new braided stainless steel lines. They’re affordable, reliable, and easy to install.
3. Repair or Replace Shut-Off Valves
If water is seeping from a shut-off valve, tightening the packing nut may help. If not, the valve may need to be replaced.
4. Replace Faucet O-Rings
Water inside the faucet body can leak downward if internal O-rings are worn. Many manufacturers sell inexpensive repair kits for this issue.
5. Fix the Drain Assembly
If the leak is from the drain, reseal the flange with plumber’s putty or silicone and tighten the locknut. Replace gaskets if worn.
Estimated Costs of Repairs
- Replacement supply lines: ₦3,000–₦12,000 ($10–$30 internationally).
- Shut-off valve replacement: ₦8,000–₦25,000 ($20–$60 internationally).
- Faucet repair kit (O-rings, seals): ₦5,000–₦15,000 ($15–$40 internationally).
- Professional plumber service: ₦10,000–₦40,000 ($80–$200 in the US).
How to Prevent Future Leaks Under the Sink
- Inspect supply lines every 1–2 years and replace if worn.
- Turn shut-off valves occasionally to keep them from sticking.
- Clean mineral deposits from faucet connections to protect seals.
- Place a drip tray or mat under the sink to catch minor leaks before they spread.
FAQs
1. Is a faucet drip under the sink dangerous?
Yes. Even slow drips can cause significant water damage, mold growth, and cabinet warping if ignored.
2. Can I use plumber’s tape to stop the leak?
Yes, Teflon tape can help seal threaded connections, but if a hose or valve is damaged, replacement is the better fix.
3. How long do faucet supply lines last?
Braided stainless steel lines last about 10 years. Rubber lines should be replaced every 5 years or sooner if cracks appear.
4. Do I need a plumber to fix a drip under the sink?
Not always. Tightening connections and replacing hoses are DIY-friendly. But if the shut-off valve or faucet body is damaged, hiring a plumber is wise.
5. Can I still use my sink if it’s dripping underneath?
It’s best to turn off the water and fix the issue immediately. Continued use risks worsening leaks and property damage.
Conclusion
If your faucet is dripping under the sink, don’t ignore it. Most of the time, the problem is a loose connection, worn supply line, or faulty shut-off valve—all of which are quick and affordable to repair. By diagnosing the source early and making the right fix, you can protect your cabinets, floors, and wallet from costly water damage.