Skip to Content

What Causes Low Water Pressure in Bathroom Sink? 5 Ways to Fix It

What causes loss of water pressure in bathroom sinks?

Low water pressure in your bathroom sink faucet can be a huge pain. Luckily it’s a pretty common problem and the solution is usually pretty easy to trace and can be fixed by most homeowners. Here are the frustrating causes of low water pressure in your bathroom sink and how to fix them.

What Causes Low Water Pressure in Bathroom Sink

Source the low-pressure problem

Before we begin it’s important to determine if there is a lack of water pressure in your whole house (which is a bigger issue) or if a limited water flow is isolated to your bathroom faucet.

To see if there are low flow issues in the rest of the house, go and turn on other faucets one at a time in different rooms to see if the water pressure is the same as it’s always been or if the flow of water is slowing down.

If the rest of the house has comfortable water pressure, you know it’s a bathroom faucet sink-specific issue. The next thing to do is determine if the water pressure is low all the time or sporadically.


Determine if it’s a temporary issue

The reason for checking this is because water can be used in other parts of the house at the same time. When that happens, it can cause a decrease in water pressure.

For example, if your whole family gets up at the same time, you could have multiple faucets running all at once, not to mention showers and toilets flushing as well.

All these fixtures running together can be the reason for weak water pressure in your house. But if you are just using your bathroom sink, you may think that it’s specific to that one spot, when in fact, it’s just a timing issue.

Assuming you have checked these two things and still have low hot water pressure in your sink, it’s time to get to the specifics.


Click Here to Find a Local Plumber



Check hot and cold water pressure separately

We want to see if the bathroom faucet’s water pressure is conditional on the cold water faucet or the hot water faucet. It could be that there is a water pressure issue with just the hot water or just the cold line.

Test each of the water supply lines to see if the water pressure is the same. You do this by turning on each bathroom sink faucet water to full one at a time, checking if there is a reduction in flow and then turning the bathroom faucets off.

If you find that the hot water pressure is weak, but the cold water pressure is strong, you know that there is a hot water pressure issue in the hot water supply line.

This is great because you are narrowing down your issue. At that point, it may be a low hot water pressure issue or a water heater leak issue.

Inspect your water heater and make sure there are no wet spots around the tank or that the water heater isn’t leaking from the bottom. 

The more you can narrow down the source of the low hot water pressure in your water system lines, the easier it will be to fix the water pressure in the bathroom sink. 


Check the cold and hot water shut-off valves are fully opened

bathroom sink shut off valve

If you have recently replaced your taps, you will want to check both the cold water valves and the hot water valves are fully open.

When the taps are replaced the ball valves get turned to the off position. Once the new taps are on they aren’t fully opened (meaning the valves are partially closed) and are the culprit for bathroom sink water pressure issues.

These knobs are in the sink cabinet and can get bumped and end up being partially closed.

Inspect the cold water and hot water shut-off valves to see if they are fully open. To see if they are fully open, turn them completely until you know the water flow is open.


Check the Bathroom Faucet Water Aerator

Water Pressure Low in Bathroom Sink (1)

The first thing you can check once you know the shut off valve is fully open is the bathroom sink faucet water aerator. The aerator on a bathroom sink is made of metal or plastic and is a mesh that is designed to aerate the water, giving it a better flow and is located on the end of the faucet. It also filters any dirt or other things in your pipes making their way to your sink.

Faucet Water Aerator

Because the aerator serves as a filter, it can become plugged over time. Take a look at the aerator and see if the mesh is plugged at all. Any blockage in this will significantly cut down the water pressure in your bathroom sink. This is often the source of many low water pressure issues.

Parts of a Faucet Water Aerator


How to fix the water aerator

To fix this low water pressure issue, remove the aerator from the end of the bathroom faucet by unscrewing it.  Usually, you can do this by hand, but if the mineral deposits and build-up is old, you may need a wrench. Never use pliers as they can bend the plumbing fittings. If you need to understand the parts of a faucet aerator, see the image.

Inspect the aerator to see if there is an issue with the holes. If the aerator’s holes are plugged from mineral deposits, you can scrub it with a cleaning toothbrush while running it under water. Alternatively, you can try to clear out the holes with a safety pin as well if you prefer.

If there is excessive hard water buildup, you can put the wire mesh in a vinegar and water solution overnight. Leaving it in vinegar overnight will help break down the mineral buildup and remove any of the hard water buildup that have occurred. Once you have done that, rinse it in the morning and put it back into place.


Check the water flow restrictor

What is a water flow restrictor?


water flow restrictor

Before you can check the flow restrictor, you need to know what that is. A flow restrictor is a small plastic disc inserted into the tap just before the faucet aerator. It has a hole or many holes in it, and it regulates the flow of water from the tap by restricting how much water can come through at any given time.

How to check the flow restrictor disk

Remove the clogged aerator and inspect the plastic disk known as the flow restrictor. Check the flow restrictor to see if there is a big enough hole for the water to be coming through and make sure there are no clogged holes. If there is any build-up on the restrictor, you can clean it. 

Over time mineral deposits from your water can build up on the aerator and begin to clog the holes. As this happens, your water pressure will become less and less.


How to fix the water flow restrictor disk

The easiest way to fix the low flow restrictor issue is to remove the clogged aerator piece at the end of the bathroom faucet. Usually, you can unscrew this with your hand, but depending on the faucet you may need a wrench.

Remove the plastic disk inside the aerator and clear the holes using a safety pin. You can also widen the holes using a screwdriver or a sharp knife if you believe that is the issue.

Alternatively, if there is some buildup on the flow restrictor, you can remove the mineral buildup by soaking it in vinegar overnight and putting it back in place in the morning.

The question that often comes up is, “Should I remove the flow restrictor disc completely?”

While this is an easy way to increase water flow, it can also significantly increase the water usage of a bathroom faucet and end up costing you money. When it all possible, it is best to slightly widen the holes or remove the build-up, as we previously mentioned.


Click Here to Find a Local Plumber



Clogged Water Supply Lines

If none of the above have worked to improve your low water pressure, you may have a plugged water supply line. This happened to us when we built our house, there was a bit of dirt and debris in the water lines, and it needed to be flushed out. Apparently, it’s pretty common in building new houses.

It’s a fairly simple thing to fix but sounds a lot more complicated. So let’s break down what you need to do to flush your water supply line and restore water pressure.


Here’s how to flush your water lines

Flushing your water lines is a great way to ensure thorough cleaning of your supply lines. 

Step 1: Turn off the shut off valves

First, turn off the shut-off valves located under your bathroom sink. Turn them both clockwise until they are completely turned to the off position. You can also turn off the water at the main shut-off valve, but that turns off water to the whole house. 


Step 2: Check the water is off and drain the lines

Next, turn on the hot and cold faucets. We do this to remove any water that is still in the line after the water drains out of the lines. Once they have been drained, turn the faucets off again.


Step 3: Remove the water line from the faucet

Next, you will want to remove the water supply line from the faucet. Use a wrench and remove the water lines from underneath your faucet in the sink cabinet. These can be in a hard-to-reach area, and you may need a different type of wrench to do this.


Step 4: Flush the lines.

Get a bucket and put your water supply valves into the bucket. Next, turn on the water shut-off valves to the on position. The water will start to come out of the supply lines and into the bucket. Let the water run for about 30 seconds. This should remove anything in the plugged water supply lines.


Step 5: Reattach the water lines to the faucet

Turn off the shut-off valves again and reconnect the water lines back onto the faucet.
You will want to make sure you tighten them with a wrench; they don’t need to be super tight (like we did when replacing the water supply line). Lastly, reopen the shut-off valves and turn on your faucets to see if the water pressure has improved. If you opted to turn off the main shut off valve, instead turn it back on too. 

Check underneath your sink to make sure everything is connected properly and not leaking. A great way to make sure you detect any leaks is to use a wifi water sensor, we have one, and it’s caught several leaks for us in the past year.

Turn on the water and see if your water pressure has improved. 


Check for water leaks

Another reason for low water pressure is that there is a water leak somewhere. Over time water will wear down parts of your plumbing, and it could be that you have a leak somewhere. 

Inspect your bathroom fixtures to see if there are any water leaks under the countertop.

We recently had a flexible hose leak under our kitchen sink, and it was an easy fix. Depending on where the leak is coming from, you may be able to fix it yourself, or you may need to call a plumber.

Check the hot water heater

If you just have no hot water pressure you should check the hot water heater. There could be a few reasons. First, check the pilot light on the hot water tank to make sure it is on. Then look around the water tank to see if there is any water coming out of the unit. Water heaters can leak from the bottom or from the top of the water heater, either way this is the source of your low hot water pressure problem. 

Your water heater has a limited lifespan. If it starts to break down it could leak and then the water will be all over the basement. 

If your hot water heater is leaking you will have low pressure in the bathroom sink and likely everywhere in the house. Turn off the water to the unit and the power, next you will need to flush the hot water heater so that you can remove it and replace it. 


Lastly, call a plumber

If you try all of these low water pressure fixes in your bathroom sink faucets and nothing works, it could be something larger. At this point, you should contact a professional plumber. You have done everything you can, and by calling in a professional, they can assess the issue and fix it quickly.


Click Here to Find a Local Plumber



Looking for more repairs and maintenance? Read this:


This post may contain affiliate links which go towards keeping this site running. Please see our Disclaimer and Privacy Policy for more. We are a member in the Amazon Affiliate Program. Thank you for your support!