Bathroom Faucet Leaking At Base? (We Have a Few Fixes)

Kellan Jansen
by Kellan Jansen

Leaks are never fun. However, it’s important that you deal with them quickly. Fail to do so and you could end up with costly repairs, skyrocketing water bills, and other negative consequences of your inaction.

When diagnosing a leak, it’s helpful to be able to identify where the water is actually coming from. For example, maybe you’ve identified that your bathroom faucet is leaking at its base. If so, you’ve come to the right place.

Shut off the faucet water supply and pull out the faucet handle cap. Loosen the faucet valve with a pair of pliers and find the internal O-rings. Remove and replace the damaged O-rings so that the faucet doesn’t leak at the base.

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What Causes Bathroom Sinks to Leak at the Base?

It’s useful to identify what the “base” of a faucet actually is before diving into this. When we talk about a base leak, we mean to talk about where the faucet meets the sink. Base leaks can sometimes be difficult to spot because they typically only leak when the faucet is on. Additionally, they occur in a spot that we commonly splash water on while using our sink.

That being said, there are really only two culprits that could be causing your sink to leak at its base. The first is the faucet’s O-ring. These can dry up or crack after extended use.

The second potential cause of your problem is a worn-out inner cartridge. Once again, the most common reason for this problem is simply extended use. Read on to learn what you need to do to fix these problems.

How to Fix Bathroom Faucet Leaking at Base

Faulty O-rings are the most common reason why faucets leak at their base. With that in mind, you’ll want to try fixing that first. If, after you try to fix your faucet’s O-ring, the problem still occurs, then you can proceed to replacing its inner cartridge. With that in mind, here are step-by-step guides that you can follow to repair your leaking faucet.

Replace the Faucet’s Internal O-Ring

Materials Needed

Prepare yourself for this project by making sure that you have the right materials for the job. Here’s what you should have on hand:

  • Screwdriver set
  • Replacement O-rings
  • Adjustable pliers or a wrench

1. Shut Off the Faucet’s Water Supply

In most cases, this is done by locating the how and cold water valves underneath the sink. All you need to do is rotate each of them in a clockwise direction. Once you do, turn the faucet’s handles to make sure they release any remaining water.

2. Pop the Faucet Handle Cap Off

You’ll do this with a screwdriver. Take the slotted end of the screwdriver and stick it underneath the center of the handle. Here, you’ll find what’s called a pop cap. You can pop it off with the screwdriver. Doing this will give you access to the screw that connects the valve stem to the handle.

3. Remove the Screw Cap Handle

A Phillips screwdriver is usually the best tool for the job. Once you’ve done this, grab the handle, pull it straight up, and remove it from the valve stem. You may find that your sink has decorative caps blocking you. Just remove these if you need to.

4. Loosen the Valve from the Faucet Body

Do this with the pliers or wrench that you have on hand. Secure your tool of choice around the valve’s base. Then, rotate in a counterclockwise direction. This will loosen the valve from the faucet body. At a certain point, you should be able to just pull up on the base to dislodge the valve.

5. Find the O-rings and Pull Them Off

These should be on the valve body. Once you’ve gotten the old O-rings off, you can go ahead and place the new ones on.

6. Put Everything Back Together

Start by sliding the valve back into the faucet body. As you work, make sure that you align any tabs or grooves that you find to ensure a tight fit. Then, tighten the valve with your pliers or wrench.

Finally, slip the faucet handle over the valve stem, insert the screw in the center of the handle, and pop the handle cap back on.

7. Test the Faucet

If everything worked out, your faucet should be back to normal. You can verify by turning the faucet on and just looking to see if any water leaks out of the base. If you still see a leak, then proceed to the next guide showing you how to replace the faucet’s inner cartridge.

Replace the Faucet’s Inner Cartridge

It’s possible that your faucet’s worn-out inner cartridge is the cause of its leak. This is the part of the faucet that controls the flow of water into the faucet spout. Replacing the inner cartridge with a new one could be just what you need to solve the leaks you’ve been having.

Before starting, it’s important to note that sinks with two handles often have inner cartridges in each handle. If your leak is coming from only one of those handles, then don’t worry about replacing the other handle’s inner cartridge unless you want to be proactive.

Materials and Tools Needed

Here’s what you’ll need to tackle this job:

  • Allen wrench
  • Pipe wrench or tongue-and-groove pliers
  • Phillips and Flathead screwdrivers
  • Replacement cartridge(s)
  • Plumber’s grease

1. Turn Off the Water Supply

This is typically done underneath the sink. You should find two shutoff valves under your sink that have small, football-shaped handles. If you don’t see that, look for a valve that has a lever that you can rotate. You can turn these off by turning them clockwise until you can’t anymore.

If you aren’t able to find shutoff valves under your sink, you’re going to need to turn off your home’s main water valve while you work. This will make sure that water won’t interfere with you while you work.

2. Remove the Faucet Handle

Most handles have screws that you can find pretty easily either on their sides or rears. If you don’t see screws, your handle might have a decorative cap that you need to pop off by wedging a screwdriver underneath it.

Either way, you need to find the screw that attaches the handle to the faucet and remove it. Once you’ve done that, you can pull straight up on the handle to remove it from the faucet entirely.

3. Find the Retaining Nut and Remove it

This is located right on top of the cartridge. You’ll probably need to use either your pipe wrench or tongue-and-groove pliers to loosen it. Be sure to save the screw so that you can use it to secure the new cartridge you’re installing.

4. Remove the Old Cartridge

This is fairly straightforward. However, before you pull the old cartridge out, note the way that it’s oriented. You may even want to take a picture so that you know how to install the new one in the same way.

5. Install the New Cartridge

Start by placing the new cartridge into the slot just like the old one. Then, replace the screw you took out earlier on top of the cartridge to secure it into place. You may need to apply a bit of plumber’s grease to the cartridge’s O-ring with your finger. This will help the cartridge fit into its housing.

6. Put it All Back Together and Test the Faucet

Finish the project by replacing everything that you had to take apart to install a new cartridge. Once you’re done with that, turn the sink’s water supply back on and test it out. If you’ve made it this far, your leaking bathroom faucet should be finally fixed.

Do You Need a Faucet, Fixture, or Pipe Repair or Replacement?

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Bathroom Faucet Leaking at Base and Under Sink

Sometimes bathroom faucets will leak both at their base and under the sink. When this happens, it doesn’t necessarily mean that you have a more serious issue than you would if the leak was isolated at your faucet’s base.

In fact, the leak that’s being caused by a faulty O-ring or worn-out cartridge is almost definitely the same leak that’s happening under your sink. It’s probable that the water is simply making its way from the base of your faucet to the underside of your sink. If anything, you may just have a simple PVC connection underneath your sink that needs to be strengthened.

Related Questions

How do you seal the base of a faucet?

You can seal the base of a faucet by applying a ring of putty around its edges. However, this doesn’t actually stop the leak from occurring. It just means that you won’t notice the effects of the leak for the time being. It’s still important that you eventually fix the leak in a more permanent way.

Should you caulk around a faucet?

You can use caulk around a faucet base but it’s not necessary to do so. Caulking is another way to seal your sink. It’s often used on kitchen faucets that don’t have a rubber gasket to prevent leaks.

Kellan Jansen
Kellan Jansen

Kellan is a content writer who specializes in everything DIY. When he's not behind the keyboard, he enjoys spending time with his pets, playing music, and geeking out about basketball. He hopes to make your home improvement projects a little bit easier to accomplish.

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