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Why Am I Getting Low Water Pressure in My House all of a Sudden?

January 29, 2021


A sudden drop in your home’s water pressure can be an inconvenient issue.

Depending on the details of your situation, a sudden drop in water pressure could indicate any of the following issues:

  • Faulty plumbing fixture
  • Faulty hot water heater
  • Leaking/blocked water supply pipe
  • Shut-off valve partially closed
  • Faulty pressure reducing valve (PRV valve)
  • There’s an issue with the municipal water supply system

To help you identify which issue might be causing your low water pressure, we’ve split them up according to the symptoms you might be experiencing.

Browse the sections below to determine what’s happening in your home and what you should do to resolve your water pressure problem.


Live in the New York City area and need a professional’s help? Just contact Ranshaw. Our skilled plumbers will arrive promptly to diagnose and correct your water pressure issues. Whether you need a pipe leak repair or a single fixture that needs replacing, we can help.


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If you’re suddenly getting low water pressure at only one fixture…

...the issue might be one of the following:

  • Partially closed shut-off valve
  • Dirty/clogged aerator
  • Faulty fixture

Partially closed shut-off valve

If your water pressure is low at one fixture only, the first place you want to check is the water shut-off valve. If it was closed for any reason, it’s possible it wasn’t turned back to the fully open position.

What to do: Underneath your sink, you should have a valve for both your hot and cold water supply lines. Check to make sure both are turned in the open position (counter-clockwise). If both valves are open, you can rule this out as the cause for low water pressure at your faucet.

Dirty/Clogged Aerator

As fixtures age, they often develop scale deposits that can block water flow. Over time, the minerals in the water can cling to and build up on surfaces causing scale deposits.

If the pipe and/or fixture has developed scale deposits, it’s possible that parts of the deposit have broken off and are now blocking the water supply.

What to do: Try unscrewing the faucet aerator or removing the showerhead. Inspect the parts for scale deposits (a white, pink or even brownish crust) and remove deposits if present.

If you don’t see any deposits, can’t remove the deposits or you’ve removed all deposits and the water pressure issue persists, it could be the fixture itself that’s faulty.

Faulty Fixture

There’s a component inside certain types of faucets called a cartridge. The cartridge regulates the flow of water that goes through the faucet. Unfortunately, they can develop build-up and become blocked. They can also become worn/defective with age which requires a replacement of the cartridge or the fixture itself if a replacement cartridge is not available.

What to do: Replacing a faucet cartridge involves the disassembling and reassembling of your faucet. While not impossible for a homeowner to address, you may want to consider contacting a plumber for help with this.

If you’re suddenly getting low water pressure for hot water only...

...your hot water heater could be the culprit.

Is your low water pressure only occurring with hot water? If this is a widespread issue (throughout your entire home, not just one faucet), it usually signals an issue with your hot water heater system.

What to do: Servicing a hot water heater should be done by a trained professional only. If you lost hot water pressure throughout your entire home, contact a qualified plumber for assistance.

If you’re suddenly getting low water pressure in one area of the house…

...the supply pipes to that area may either be corroded, leaking or blocked.

If all the fixtures in an entire bathroom or the entire kitchen are suddenly getting low water pressure, you can trace the issue to the plumbing pipes.

If your home has older pipes, it’s likely that one of the main pipes feeding that particular area of your home is corroded and/or blocked by scale deposits. At some point, a piece of rust or scale could have broken off and is blocking a narrow part of the pipe.

On the other hand, there may be a leak in one of the main pipes feeding that area of the home. A leak will divert water away from the fixtures and cause a sudden drop in water pressure.

What to do: Contact a plumber to diagnose the issue. If the issue is pipe corrosion or scaling, you may need a pipe replacement. If the issue is a leak, you’ll need a pipe leak repair. Both a pipe repair and pipe replacement are jobs that should be left to professionals. Learn more about Ranshaw’s pipe leak repair services.

If you’re suddenly getting low water pressure in the entire house…

...the issue might be one of the following:

  • Your home’s main shut-off valve is partially closed
  • There is a leak in your home’s water main
  • Your home’s PRV (pressure reducing valve) is faulty
  • There’s a problem with the municipal water supply

We’ll explain each of the possible issues above.

Your home’s main shut-off valve is partially closed

Every home has a main shut-off valve that controls the flow of water throughout the home. If this valve was partially closed (i.e. someone bumped it), the water supply throughout your entire home will suddenly drop.

What to do: Find your home’s shut-off valve. In New York City homes, these valves are typically located in a basement or an interior closet/storage space. Some homes have water meters installed, in which case you might see multiple valves (call a plumber if you’re not sure where your shut-off valve is located).

Check that the shut-off valve handle is completely parallel to the pipe on which it’s located. If the handle is slightly misaligned (not parallel to the pipe), it might be decreasing the water flow to your home’s appliances.

If your water shut-off valve is perfectly parallel to the pipe, this is not your issue and you’ll need a plumber to diagnose your water pressure problem.

There is a leak in your home’s water main

Every home has a water main that feeds water to the entire home. If this line suddenly springs a leak, it could result in a sudden drop in water pressure throughout the home.

What to do: Shut off all water fixtures in your home. Check your water meter and make note of the numbers you see. If after 30 minutes the numbers have changed, there’s probably a leak in your water main. Call a plumber immediately as this can become an expensive problem very quickly.

If the numbers have not changed, you likely don’t have a leak in your water main. However, you’ll want to call a plumber to come out and diagnose your water pressure issues.

Your home’s PRV is faulty

Not all residences in the New York City area have a PRV but if your home has one, it could be malfunctioning and causing low water pressure.

The PRV (pressure reducing valve) is responsible for regulating the water pressure throughout your home. When water reaches your home from the municipal water supply, it’s coming in at high speeds and high pressure. The PRV helps lower the water pressure so that it enters your home at a safe speed/pressure that won’t damage your pipes.

However, if the PRV is faulty or needs to be replaced, it can cause a sudden drop in water pressure for the entire home. PRV valves should be replaced every 12 or so years to ensure it’s operating correctly.

What to do: Have a plumber inspect your home’s PRV to see if it’s working properly or if it needs to be replaced.

There’s a problem with the municipal water supply

If your neighbors are experiencing the same whole-house water pressure issues as you, the city is likely to blame.

Sometimes, maintenance on the local water supply system can cause a sudden drop in the water supply.

What to do: Report the issue to the NYC DEP (Department of Environmental Control) here to make sure the city is aware of the problem and to see what they are doing to resolve the issue.

Need an NYC plumber to fix your water pressure issues?

Contact Ranshaw. Our plumbers have provided fast pipe and fixture repairs and replacement to homeowners in the Queens and surrounding area for the past 50 years.

Our skilled plumbers will arrive promptly to inspect your plumbing system and provide a correct diagnosis. They always arrive in a fully-stocked truck so they can typically get the job done that same visit.


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