What Causes Low Water Pressure in Only One Faucet?

Clogged Aerator

The aerator at the faucet’s tip is designed to mix air with water to create a smooth flow. However, it can also act as a trap for tiny particles like sediment and mineral deposits, which can accumulate over time. This buildup restricts the water flow, reducing pressure at that faucet. 

The Solution: Unscrew the aerator from the faucet and soak it in vinegar to dissolve mineral deposits. Use a small brush or needle to remove debris, then rinse and reattach it. If it’s too clogged, consider replacing the aerator.

Partially Closed Shut-Off Valve

Each faucet typically has a dedicated shut-off valve under the sink, which controls water flow to that fixture. If this valve is not fully open—whether due to recent plumbing work, accidental bumping, or gradual loosening—it can limit the water supply to the faucet.

The Solution: Turn the shut-off valve beneath the sink counterclockwise to ensure it’s fully open. This adjustment should help restore normal water flow to the faucet.

Clogged or Damaged Cartridge

Many faucets, particularly single-handle models, contain a cartridge inside the fixture that helps regulate water flow and temperature. Over time, this cartridge can become clogged with mineral deposits or debris, especially if your area has hard water. A clogged cartridge restricts water flow, leading to lower pressure. 

The Solution: Shut off the water supply and remove the faucet handle to access the cartridge. Clean or replace it as needed. If cleaning, soak the cartridge in vinegar to dissolve buildup. If damaged, replace it with a new one compatible with your faucet model.

Build-Up in Pipes

Pipes that feed water to individual fixtures can accumulate scale, rust, and mineral deposits, particularly in older plumbing systems. Over time, these deposits can narrow the pipe’s interior, restricting water flow and reducing pressure at the affected faucet. 

The Solution: This type of buildup may require flushing the pipe. Turn off the water, disconnect the faucet, and briefly turn the water back on to flush out any debris. For more significant buildup, a plumber may need to inspect and clean the pipes to resolve the issue fully.

Leaks in the Faucet or Supply Line

Small leaks in the faucet or the supply line connecting it to the main water line can lead to a gradual loss of water pressure. Even a minor leak can cause water to escape before it reaches the faucet, resulting in lower flow at the fixture.

The Solution: Inspect the faucet and supply line for visible leaks. Tighten any loose connections or replace damaged parts if necessary. If you cannot locate the leak or need further repairs, a plumber can help fix the issue.