Why Does Only One Faucet in My House Have Low Water Pressure?

When a single faucet in your home suddenly has low water pressure but everything else works fine, it’s usually a sign of a localized issue—not a problem with your entire plumbing system. This actually makes troubleshooting easier because the problem is almost always isolated to that specific fixture or the piping feeding it. Here are the most common causes and what they mean.

1. A Clogged Aerator

The aerator is the small screen attached to the tip of the faucet. Over time, minerals from hard water, sediment, and tiny debris can build up inside it. When the screen becomes partially blocked, water flow drops dramatically, especially with older faucets.

Quick fix: Unscrew the aerator, clean it with vinegar, rinse it, and reinstall it. If pressure returns, the aerator was the issue.

2. Sediment Buildup Inside the Faucet

If cleaning the aerator doesn’t help, the clog may be deeper inside the faucet body. Old cartridges, mixing valves, or internal passages can develop blockages, especially in homes with scale-heavy water.

What to do: The faucet may need to be disassembled, cleaned, or have its cartridge replaced.

3. Partially Closed Shut-Off Valves

Every faucet has two small shut-off valves—one for hot, one for cold—usually located under the sink. If someone recently worked under the sink or bumped the valve, it might be partially closed, restricting water flow.

Check this: Make sure both valves are fully open by turning them counterclockwise.

4. A Faulty Faucet Cartridge

For single-handle faucets, the internal cartridge controls both flow and temperature. When it gets worn out or clogged with sediment, it can reduce pressure on one or both sides.

Signs: Low pressure only on hot or only on cold water often means a cartridge issue.

5. A Supply Line Kink

The flexible supply lines that connect the shut-off valves to the faucet can become kinked or twisted—especially after someone stores items under the sink or moves the plumbing during repairs.

Fix: Inspect the lines. If they’re kinked or collapsing, replacing them is inexpensive and fixes the pressure immediately.

6. Corroded or Damaged Pipes Feeding That Fixture

If your home has older galvanized steel pipes, corrosion can slowly choke off water flow in certain sections. When only one faucet is affected, that branch line may be deteriorating.

This is likely if:

• The faucet is in an older part of the home
• Water appears rusty or discolored when first turned on
• Pressure has slowly declined over months or years

This requires a plumber to inspect the lines and possibly replace the affected section.

7. A Problem With the Faucet Itself

Sometimes the faucet is simply failing. Cheap or aging fixtures can develop internal blockages or mechanical failure. In these cases, replacement is often cheaper and easier than repair.

8. Hot Water Issues Coming From the Water Heater

If the faucet has low pressure only on the hot water side, sediment buildup inside the water heater or along the hot water lines may be restricting flow.

Clues:

• Hot water pressure is low at only one faucet
• Other fixtures have normal hot water flow

The heater may need to be flushed or have the hot-side piping inspected.

When to Call a Plumber

If cleaning the aerator and checking the shut-off valves don’t fix the issue, the cause is likely deeper in the faucet assembly or the piping. A professional plumber can identify whether the problem is a failing fixture, internal clog, or pipe issue and get your pressure back to normal quickly.

A single low-pressure faucet is usually a simple fix—but ignoring it can lead to bigger plumbing issues later on.