Low Water Pressure In Bathroom Sink? 4 Reasons and 8 Fixes

Ugh! You turn on the water in the bathroom sink and a pitiful amount of water flows into the sink. How are you supposed to wash your hands or brush your teeth with such a piddly amount of water?! Luckily, there is no reason to struggle with low water pressure in bathroom sink. It’s easy to diagnose and fix yourself: here are 4 reasons why the water pressure in the bathroom sink might be low, and 8 ways to fix it yourself.

Low Water Pressure in Bathroom Sink

The first thing to check is whether the water pressure is low only in the bathroom sink, or is it low in other areas of the bathroom and rest of the house? Is the shower running at full pressure? What about the kitchen sink? This can help you determine if you have a localized, bathroom faucet water pressure problem, or something more systemic that might need more of a professional diagnosis.

If the kitchen, or other areas of the house also have low water pressure then the best thing to do is call a plumber and see if they can’t diagnose the problem. It could be as simple as an intake valve needing some maintenance, to perhaps the pipes leading to your home needing a thorough cleaning. Best to leave that to the professionals.

But, if it truly is just the bathroom faucet that is suffering from frustratingly low water pressure, there are a few things that can be done about it.

4 Reasons For Low Water Pressure in Bathroom Sink And 8 Ways to Fix It

1. Flow Restrictor In Place

flow restrictor
The white plastic disc is the flow restrictor. Notice how it essentially plugs the faucet with only small holes to let water through.

The first thing to look for if the water pressure in the bathroom faucet is too low is to check to see if there is a flow restrictor in place. These devices are designed to do exactly what they are named for; they restrict the amount of water that is released from the faucet.

What is a water flow restrictor? It’s a small plastic disc with a hole in it that is inserted into the faucet just inside of the aerator mesh. There are a few reasons why this might be a problem in your bathroom faucet:

  • The hole in the flow restrictor may be too small and is not letting enough water flow through
  • The hole in the flow restrictor may be plugged, or partially plugged, further restricting the water flow

Ways to Fix It:

There are 3 ways to fix a low flow restrictor problem:

  1. Increase the size of the restrictor hole. Do this by unscrewing the aerator piece from the end of the faucet. You should be able to do this by hand, but may need the help of a small wrench if it is very tight. Inside the aerator piece is the flow restrictor; remove it and increase the size of the hole by inserting a screwdriver head, or the end of a sharp knife etc and turning to remove some of the plastic. Return the restrictor and the aerator to the faucet and test. Repeat if the water is still not flowing as strongly as you would like.
  2. Clean the restrictor to unplug the hole. Access the restrictor (again, by removing the aerator piece from the end of the faucet). Clean the restrictor first to remove any visible dirt and grime. Oftentimes it is mineral buildup that causes the hole to plug; solve this by dropping the restrictor into vinegar overnight to dissolve the minerals and open up the restrictor hole. Return the aerator/restrictor piece to the faucet and test.
  3. Remove the flow restrictor. While not an ideal solution, it is possible to remove the water saver all together and let the water flow freely.

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2. Plugged Water Aerator

water aerator

The water aerator at the end of the faucet is made of wire mesh and has two functions. First it breaks up the flow of water and aerates it providing a more consistent and comfortable water flow. It also acts as a filter at the end of the faucet; collecting dirt and debris that may be flowing through the pipes to your bathroom sink.

It is, of course, the filter function that can ultimately cause problems regarding water pressure. As the filter becomes plugged with debris, the amount of water that can flow through is decreased. This is noticed by a reduction in water pressure and a less than desirable amount of water flowing from the faucet.

Ways to Fix It:

  1. Clean the aerator. Remove the aerator from the end of the faucet by unscrewing it. You should be able to do this by hand but may need a small wrench if it is screwed on tightly. Clean the wire mesh by rinsing it under the water and brushing with a scrub brush or old toothbrush. This should remove any visible debris and may be enough to improve the water pressure enough. If not, then it may be mineral deposits that are the culprit. Soaking the aerator in vinegar overnight will dissolve any mineral deposits and leave the wire mesh aerator free of any plugging that is causing the issue.
  2. Replace the aerator. If cleaning the aerator and removing the mineral deposits doesn’t work, then it may be time to replace the faucet water aerator. Luckily these are readily available and are inexpensive; you may even want to keep a small stock of them on hand if you live in an area with hard water as the aerator may be prone to clogging with mineral deposits from the water.

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3. Incompletely Opened Shut Off Valves

water shut off valves

A more systemic, but easily solved, reason might be that the water shut off valves located below the sink are not completely open. Perhaps they were not opened properly after closing them to do some regular maintenance, or for winter shut down. If your under-the-bathroom-sink looks anything like mine, then perhaps an errant shampoo bottle or toothpaste stock knocked into the valve taps and partially closed the valve. Either way the fix is super simple.

Ways to Fix It:

  1. Ensure the water supply valves are fully open. The hardest part of this fix might be cleaning out under the sink to get to the valves! Once you have access, simply ensure that both the hot water and the cold water valves are fully opened. I always remember the funny saying ‘lefty loosey, righty tighty’ to remember which way to turn the valves. Open them fully by turning to the left, or counter-clockwise.

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4. Plugged Water Supply Lines

water supply line

This is a bigger issue, but it’s still well within your skill-set to fix it!! In the same way that dirt and debris can plug up the aerator in the faucet, it is possible that the water supply lines could be plugged. This is usually an issue in new home buildings where construction debris may have made its way into pipes clogging them before they are even used. It could also be an issue in older homes, especially those in hard water areas. Over time those mineral deposits can really build up, gradually narrowing the water supply lines causing water pressure issues.

Ways to Fix It:

  1. Flush the water supply lines. Depending on just how plugged the supply lines are, you may be able to simply flush the lines to resolve the pressure issue.
    • Do this by first closing the water supply valves by turning them clockwise (remember ‘righty tighty’?). 
    • Then, open the hot and cold water faucet from above to release the water remaining in the water supply lines.
    • Using a wrench, release the water supply lines from the underside of the faucets – placing the ends into a bucket under the sink.
    • Turn the water supply valves on one at a time and let it run for 10 seconds into the bucket.
    • Return the supply lines to the underside of the faucets, turn the water supply valves back on, and test the water pressure.
  2. Clean the water supply lines. If flushing doesn’t work then it is likely a mineral deposit build up that is causing the problem.
    • Close the water supply valves by turning them clockwise. Turn the faucets on to release the water in the lines.
    • Using a wrench, remove the water supply lines from both the underside of the faucets and from the water supply valves.
    • Place the water supply lines in a bucket filled with a 50/50 solution of vinegar and water. You may need to siphon some of the solution through the lines to ensure that the interior is in contact with the solution. Leave the lines in the solution overnight and then rinse.
    • Attach the water supply lines back to the water supply valves and the undersides of the faucet. Turn the water back on and test.
  3. Replace the water supply lines. It may be possible that the build up is too much and the water supply lines need replacing. As you have already removed the water supply lines to flush and clean them, this is a simple task. Water supply lines are relatively inexpensive to replace and are easy to find.

Final Solution? Call a Plumber

If none of these do-it-yourself solutions result in better water pressure in your bathroom faucet, then your next step should be to call a plumber. They will be able to help you diagnose the problem and hopefully fix it without lightening your wallet too much!

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Low Water Pressure