How to Fix Low Water Pressure in a Sink

That frustrating trickle. You turn on your kitchen or bathroom sink expecting a steady stream, but instead, you get a weak, sputtering flow that makes washing hands, doing dishes, or even filling a glass a time-consuming chore. Low water pressure in a single sink is a common household annoyance, but the good news is that you can often fix it yourself without calling a plumber. The cause is frequently a simple clog of mineral deposits and sediment that has built up over time in a very specific, and very accessible, part of your faucet. This comprehensive guide is designed to walk you through the entire process of diagnosing and resolving the issue, starting with the most common culprit: the faucet aerator.

In this article, you will learn the step-by-step method to inspect and clean your faucet's aerator, a fix that resolves the problem more than 80% of the time. We’ll cover the tools you’ll need, how to safely remove the components, the best methods for cleaning out stubborn grime, and how to put it all back together for a perfectly restored flow. Furthermore, if that initial step doesn’t solve the problem, we won’t leave you hanging. We will explore the next logical steps in troubleshooting, including checking the water supply valves, inspecting the supply lines, and tackling a potentially clogged faucet cartridge. By following these instructions, you’ll not only learn how to fix low water pressure in your sink but also gain the confidence to handle one of the most frequent plumbing issues in any home.

Understanding the Common Causes of Low Water Pressure in a Single Sink

Before you start unscrewing parts, it's helpful to understand what might be causing the problem. When the low pressure is isolated to just one sink, it's almost certainly a problem with the faucet itself or the immediate pipes leading to it, rather than a major plumbing issue with your whole house. This is actually great news, as it means the fix is likely localized and manageable.

The Number One Suspect: A Clogged Faucet Aerator

The aerator is the small, screened cap at the very tip of your faucet spout. Its job is to introduce air into the water stream, which creates a smoother, non-splashing flow and conserves water. Because it has a fine mesh screen, it acts as a final filter for any sediment, mineral scale (like calcium and lime), or tiny debris that might be traveling through your pipes. Over months or years, this material builds up and physically blocks the water from passing through freely, resulting in a significantly weaker stream. This is by far the most common reason for a sudden or gradual drop in water pressure at a single faucet and is always the first thing you should check when you need to fix low water pressure.

The Second Possibility: A Clogged Faucet Cartridge

Inside the body of a modern faucet is a component called a cartridge. This is the mechanism that controls the flow and temperature of the water when you move the handle. It has small internal channels and rubber O-rings that can become clogged with the same sediment and mineral deposits that block an aerator. If cleaning the aerator doesn't restore your water pressure, a blocked cartridge is the next most likely cause. This fix is a bit more involved as it requires partially disassembling the faucet handle and body, but it is still a very achievable DIY project for most homeowners.

Other Potential Issues

While less common, a few other issues could be at play. The shut-off valves under the sink could have been accidentally turned partially closed, restricting the flow. In rarer cases, the flexible supply lines connecting the valves to the faucet could be kinked or internally clogged. We will explore how to check for these issues after addressing the more frequent causes.

Step-by-Step Guide: Cleaning the Faucet Aerator to Fix Low Water Pressure

This is the first and most important step in your troubleshooting journey. It's easy, requires minimal tools, and is highly effective. Don't be tempted to skip this and assume the problem is more complex until you have given the aerator a thorough cleaning.

Step 1: Gather Your Tools and Materials

You won't need much for this task, which is part of what makes it such a great starting point.

Pliers or an adjustable wrench: For providing the grip needed to unscrew the aerator housing. It's crucial to use them carefully to avoid scratching the faucet's finish.
A thick rubber band or a rag: This is your secret weapon against scratches. You’ll wrap this around the aerator housing before applying the pliers.
A small bowl: To hold the parts and for soaking.
White vinegar: This is excellent for dissolving mineral deposits like calcium and lime scale.
An old toothbrush or a small scrub brush: For physically removing stubborn debris.
A paperclip or safety pin: Useful for poking out debris from the individual screen holes.

Step 2: Carefully Remove the Aerator Housing

The aerator assembly is the threaded piece at the end of the faucet. Most screw on and off with a standard counter-clockwise motion.

Inspect the Aerator

First, try to unscrew it by hand. If it's on tight, which is common, it's time to use your tools. Wrap the rag or a thick rubber band around the metal aerator housing. This will protect the chrome or other finish from being scratched by the teeth of your pliers.

Use Your Pliers

Grip the covered aerator housing firmly with your pliers or wrench. Apply slow, steady pressure in a counter-clockwise direction (remember: "righty-tighty, lefty-loosey"). It shouldn't require extreme force. Once it breaks free, you should be able to finish unscrewing it by hand. Be prepared for a small amount of water to drip out.

Step 3: Disassemble and Clean the Components

Once you have the housing off, you'll see the components inside. Typically, there's a screen, a rubber washer, and a flow restrictor. Carefully lay these parts out in order on a towel so you remember how they go back together.

Initial Rinse and Inspection

Run the parts under a gentle stream of water from another sink if possible, or use the bathtub faucet. You will likely see a surprising amount of black, white, or brown grit come loose immediately. Look closely at the screen; you'll probably see that many of the tiny holes are completely blocked.

The Vinegar Soak

Place all the small parts of the aerator into your small bowl and pour in enough white vinegar to completely submerge them. Let them soak for at least 30-60 minutes. For very heavy mineral buildup, you can leave them for a few hours. The acetic acid in the vinegar will work to dissolve and loosen the calcium and lime deposits. You may even see some fizzing as it works.

Scrubbing and Final Cleaning

After the soak, use your old toothbrush to scrub every part, especially the fine mesh screen. Gently scrub both sides to dislodge all the softened gunk. If any holes in the screen are still blocked, use the tip of a paperclip or safety pin to carefully poke them clear. Rinse everything thoroughly with clean water to remove all traces of vinegar and debris.

Step 4: Reassemble and Test

Now it's time to put everything back together. Reassemble the aerator components in the reverse order you took them apart. Ensure the rubber washer is seated correctly, as this is what creates the seal and prevents leaks. Screw the aerator housing back onto the faucet by hand, turning it clockwise until it's snug. For the final tightening, you can use your pliers and rag again for a gentle quarter-turn, but do not overtighten, as this can damage the washer.

Turn on the water. In most cases, you will be rewarded with a strong, full, and perfectly aerated stream. You have successfully managed to fix low water pressure in your sink.

What to Do If Cleaning the Aerator Doesn't Work

If you've cleaned the aerator thoroughly and the pressure is still low, it's time to investigate a little further. The next logical step is to check the faucet's cartridge. This process is more involved but still well within the scope of a determined DIYer.

Step 1: Checking the Water Supply

Before you take the faucet apart, perform two quick checks under the sink.

Check the Shut-Off Valves: Under the sink, you'll find two valves (one for hot, one for cold) that control the water flow to that specific faucet. Make sure both valves are turned fully counter-clockwise, which is the fully open position. Sometimes they can get bumped or were never fully opened after a previous repair.
Inspect the Supply Lines: Look at the flexible tubes running from the shut-off valves to the faucet. Ensure they are not bent or kinked in a way that would restrict water flow.

Step 2: Cleaning or Replacing the Faucet Cartridge

If the valves and lines look good, the problem is likely a clogged cartridge.

Tools and Preparation

You will need a few more tools for this job: a hex key set (Allen wrenches), a Philips head screwdriver, and potentially a special cartridge puller depending on your faucet model (though often not necessary). First and foremost, you must turn off the water using the shut-off valves under the sink. Turn them fully clockwise until they stop. Turn the faucet handle on to drain any remaining water from the lines.

Removing the Faucet Handle

How the handle comes off varies by faucet type. Look for a small set screw. It's often hidden behind a small decorative cap (which can be pried off with a small flathead screwdriver) on the side or back of the handle. Use the appropriate hex key to loosen this set screw, and the handle should lift straight off.

Accessing the Cartridge

With the handle removed, you'll see the top of the cartridge. There may be a decorative cap and a retaining nut or screws holding it in place. Unscrew these carefully. Take a photo with your phone at this stage so you remember how it all goes together. Once the retaining hardware is off, you should be able to see the cartridge itself.

Removing and Cleaning the Cartridge

Grip the top of the cartridge with your pliers and pull it straight up and out of the faucet body. It might be snug, so a gentle wiggling motion can help. Once it's out, inspect the small inlet and outlet holes on the cartridge. Use your paperclip to poke out any visible sediment. You can also soak the cartridge in vinegar for about an hour, just as you did with the aerator, and then use your toothbrush to scrub it clean. Rinse it thoroughly. Also, take a moment to look down into the empty faucet body and wipe out any sediment you see in there with a rag.

Reassembly and Testing

Carefully re-insert the clean cartridge, making sure it's aligned correctly (there's usually a tab or notch to guide it). Reassemble the retaining nut, cap, and handle. Turn the water back on at the shut-off valves and test your faucet. This procedure will often fix low water pressure when the aerator isn't the cause.

When a Single Faucet Problem Might Point to a Bigger Issue

What if you've cleaned the aerator and the cartridge, and you're still experiencing low pressure? At this point, you should determine if the problem is truly isolated. Check the water pressure in other faucets in your home, both hot and cold. If every faucet is exhibiting low pressure, the problem is not with the individual sink but with your home's entire plumbing system. This could be due to a partially closed main water valve or, more likely, a failing Pressure Reducing Valve (PRV). The PRV is a bell-shaped device located where the main water line enters your home, and its job is to regulate the water pressure from the municipal supply. Adjusting or replacing a PRV is typically a job best left to a professional plumber.

Conclusion: Restoring Flow and Gaining Confidence

Dealing with low water pressure in a sink can be a real nuisance, but it rarely requires an expensive call to a plumber. By following a logical troubleshooting process, you can identify and solve the problem yourself. Always start with the simplest and most common fix: a thorough cleaning of the faucet aerator. This single step, which requires little more than vinegar and a toothbrush, will restore flow in the vast majority of cases. If that doesn't work, you now have the knowledge to confidently check your supply lines and tackle a clogged faucet cartridge. By methodically working through these steps, you not only fix low water pressure and bring your sink back to full functionality, but you also build valuable DIY skills and a better understanding of how your home's plumbing works. Enjoy your newly restored, powerful stream of water.