This just started happening today out of nowhere. When I open the kitchen faucet halfway the water pressure is ok. When I open the faucet fully the water pressure drops dramatically. Any ideas as to what the problem would be and would I be able to fix it myself or do I need to call a plumber? I’ve attached a video of me opening the faucet halfway and then fully, and also another video of the under side of the sink while opening the faucet halfway then fully. Thanks so much in advance for any help.



  • 1
    The aerator at the open end of the faucet - take it off and try again. Oct 15 '20 at 4:55
  • 1
    The previous comment suggests a simple test to see if the problem is in the aerator. If the problem does not occur with the aerator removed, then the aerator is clogged. Oct 15 '20 at 11:39
  • Is this when set purely to hot or cold water, and does this happen for any other faucet or feed (e.g. shower) in the house? If this is the only place,then you've narrowed it down to the faucet or the length of pipe to the faucet from the last junction. Oct 15 '20 at 14:30

You have a problem with the faucet valve. Those single-handle faucets have a valve that incrementally increases flow whilst also mixing hot and cold, depending on handle position.

There are various types of mechanisms to accomplish this, but a common one is the use of a hollow or solid ball with holes/ports that line up with the incoming water ports to varying degree, and lead to the spout (I mention this because your looks like that type, common manufacturer is Delta). Nevertheless, you need to turn off the water supply, remove the handle, and do some investigating. it could be as simple as a blockage that needs to be cleared, could be a new valve assembly, or could be a new faucet. We will need to see the guts...

  • 2
    Maybe the fault is in the aerator which would be a simple fix. Rule the aerator out before proceeding to test the valve. Oct 15 '20 at 11:41
  • An issue with the aerator would affect flow regardless of valve position. If you watch the linked video, flow increases and decreases in inappropropriate ways during valve manipulation. Oct 15 '20 at 17:59
  • You are probably right, but these modern aerators have more parts and it is conceivable that high flow could have this effect in an aerator. It is so simple to test by seeing if the problem persists with the aerator removed that I think it is advisable eliminating a fault in the aerator before messing with the cartridge. Oct 15 '20 at 18:53

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.