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


First source the problem

Before we begin it’s important to determine if there is a lack of water pressure in your whole house or if a limited flow of water is isolated to your bathroom sink. To see if there is low water 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 flow then you know it’s a bathroom sink specific issue. The next thing to do is determine if the water pressure is low all the time or sporadically.


Next 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 you still have low water flow and your bathroom sink it’s time to get to the specifics.


First check hot and cold water pressure separately

We want to see if the faucets 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 water line.

Test each of them to see if the water flow is the same. You do this by turning the bathroom faucet water on full one at a time, and checking if there is a reduction in water flow and then turning it 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 issue and you can narrow down your issue. At that point it may be a low hot water pressure issue or a water heater leak issue.


Check the cold and hot water shut-off valves are completely open

If you have recently replaced your tabs you will want to check both the cold water valves and the hot water valves.

These knobs are in the sink cabinet and can get bumped and end up partially closing. 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 Faucet Water Aerator

Water Pressure Low in Bathroom Sink (1)

The first thing you can check once you know the shut-off valves are fully open is the faucet water aerator. The water 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. It also filters any dirt or other things in your pipes that are making its way to your sink.

Faucet Water Aerator

Because the water 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 kind of blockage in this will significantly cut down your water flow in your bathroom sink. This is often the source of many water pressure issues.

Parts of a Faucet Water Aerator


How to fix the water aerator

To fix this remove the aerator from the end of the faucet by unscrewing it.  Usually you can do this by hand, but if the 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 aerators holes are plugged 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. This will help to remove any of the hard water buildup that has occurred, then rinse it in the morning and put it back into place.


Check the water flow restrictor

What is a water flow restrictor?


water flow restrictorBefore you can check the flow restrictor you need to know what a flow restrictor is. A water flow restrictor is a small plastic disc that is inserted into the tap just before the 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 water flow restrictor disk

Remove the 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 minerals 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 aerator piece at the end of the 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 build up 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 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.


Clogged Water Supply Lines

If none of the above have worked to improve the flow of your bathroom sink 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 new places.

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.


Here’s how to flush your water 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 off.


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 of 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. The water will start to come out of the supply lines and into the bucket. Let the water flow 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 on to 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.

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.


Lastly call a Plumber

If you try all of these low water pressure fixes in your bathroom sink and nothing works it could be something larger. At that 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.


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