Why is My Kitchen Faucet Leaking Under the Sink

A leaking kitchen faucet can be a frustrating issue, especially when it’s leaking under the sink where it can cause hidden damage to cabinets, walls, and floors. If you’re dealing with a leak under your kitchen sink, you’re not alone. This is a common problem that can arise due to several reasons, each requiring a different approach to fix. Understanding the potential causes of the leak is the first step toward finding a solution. Why is My Kitchen Faucet Leaking Under the Sink? Let’s explore the most common reasons why your kitchen faucet might be leaking under the sink and how you can address each issue.

Why is My Kitchen Faucet Leaking Under the Sink?

1. Loose or Damaged Water Supply Connections

One of the most common reasons for a leak under the kitchen sink is a loose or damaged water supply connection. The water supply lines that connect your faucet to the water supply valves are often made of flexible hoses or rigid pipes. Over time, these connections can loosen due to normal use, or they may become damaged due to wear and tear.

Solution: To check if this is the cause of the leak, start by turning off the water supply valves under the sink. Once the water is off, inspect the connections. If they’re loose, use a wrench to gently tighten them. Be careful not to over-tighten, as this can cause damage to the fittings or hoses. If you notice any visible damage or corrosion, you may need to replace the supply lines. It’s always a good idea to use high-quality, braided stainless steel supply lines, as they are more durable and less prone to leaks.

2. Faulty Faucet O-Rings or Seals

Faucets have several small O-rings and seals that prevent water from leaking out of the faucet body. Over time, these O-rings and seals can degrade or become brittle, leading to leaks. This is particularly common in older faucets or faucets that are used frequently.

Solution: To determine if faulty O-rings or seals are the problem, you’ll need to disassemble the faucet. Start by turning off the water supply and removing the handle(s) of the faucet. Once you have access to the internal components, inspect the O-rings and seals for signs of wear or damage. If they appear cracked or worn out, they should be replaced. It’s important to use the correct size and type of O-rings or seals for your specific faucet model. If you’re unsure, consult the manufacturer’s manual or take the old parts to a hardware store to find the right replacements.

3. Leaking Faucet Body or Spout

Sometimes, the faucet body or spout itself can develop leaks due to cracks or damage. This is less common than issues with supply lines or O-rings, but it can happen, especially with older or lower-quality faucets.

Solution: To check if the faucet body or spout is leaking, turn off the water supply and thoroughly dry the faucet. Turn the water back on and observe the faucet closely. If you see water seeping from the base of the faucet or around the spout, you may have a crack or defect in the faucet body. In many cases, replacing the faucet is the best solution. However, if the leak is minor and you’re not ready to replace the faucet, you can try applying a waterproof sealant around the leaking area as a temporary fix.

4. Loose Mounting Nuts or Washers

The mounting nuts and washers that secure your faucet to the sink can become loose over time, especially if the faucet is frequently moved or bumped. When these nuts or washers are loose, water can seep under the sink and cause a leak.

Solution: To fix this issue, you’ll need to tighten the mounting nuts that hold the faucet in place. This usually involves accessing the area under the sink, so it may be helpful to have a flashlight and a basin wrench. Tighten the nuts snugly, but be careful not to over-tighten, as this can damage the sink or faucet. If you notice any damaged washers, replace them with new ones.

5. Clogged or Damaged Cartridges

Modern faucets, especially single-handle designs, often use cartridges to control water flow and temperature. These cartridges can become clogged with mineral deposits or damaged over time, leading to leaks under the sink.

Solution: To inspect the cartridge, you’ll need to disassemble the faucet. Turn off the water supply, remove the handle, and then remove the cartridge. Check for signs of damage or clogs. If the cartridge is clogged with mineral deposits, you can try soaking it in vinegar to dissolve the buildup. If it’s damaged, it should be replaced. Make sure to use the correct replacement cartridge for your faucet model.

6. High Water Pressure

Excessively high water pressure can cause leaks in your plumbing system, including under the kitchen sink. High water pressure puts extra strain on faucet seals and connections, leading to leaks over time.

Solution: If you suspect high water pressure is causing your leak, you can test the water pressure with a gauge, which is available at most hardware stores. Ideally, your home’s water pressure should be between 40 and 60 psi (pounds per square inch). If your water pressure is higher than this, consider installing a pressure-reducing valve (PRV) to bring it down to a safe level.

7. Improper Installation

If your faucet was not installed correctly, it could lead to leaks under the sink. Improper installation can involve poorly tightened connections, misaligned parts, or using the wrong components.

Solution: If you suspect that your faucet was installed improperly, it may be best to have a professional plumber inspect and, if necessary, reinstall the faucet. Correcting installation errors can prevent future leaks and ensure that your faucet functions properly.

8. Cracked or Broken Pipes

Although less common, a crack or break in the pipes under your sink can also lead to leaks. This can happen due to freezing temperatures, physical damage, or wear and tear over time.

Solution: If you suspect a pipe is cracked or broken, turn off the water supply immediately to prevent further damage. Inspect the pipes for visible cracks or breaks. If you find any, you will likely need to replace the damaged section of the pipe. For significant damage or if you’re unsure how to proceed, it’s best to call a professional plumber.

Preventing Future Leaks

Preventing leaks under your kitchen sink involves regular maintenance and addressing small issues before they become bigger problems. Here are a few tips to keep in mind:

• Regular Inspections: Periodically check your faucet and plumbing connections for signs of leaks or wear.
• Replace Old Parts: Don’t wait for parts to fail before replacing them. Regularly replacing worn-out O-rings, seals, and supply lines can prevent leaks.
• Check Water Pressure: Ensure your home’s water pressure is within a safe range to prevent stress on your plumbing system.

By understanding the potential causes of a leak under your kitchen sink and knowing how to address them, you can protect your home from water damage and keep your kitchen functioning smoothly. If you’re ever unsure or uncomfortable tackling a plumbing issue yourself, don’t hesitate to contact a professional plumber for help.