Start with the aerator — the quickest fix

The aerator is the small screen at the tip of your faucet. It mixes air into the water stream and is the most common reason for low pressure in a single sink. Debris, mineral buildup, or a clogged screen blocks water flow without affecting pressure elsewhere in your home.

Unscrew the aerator by hand (turn counterclockwise). If it is stuck, wrap a cloth around it for grip. Hold it up to the light — you should see clear holes. If you see white or brown sediment, mineral deposits are blocking the screen. Rinse it under hot water and use an old toothbrush to scrub away buildup. For heavy deposits, soak the aerator in white vinegar for 30 minutes, then scrub again. Screw it back on and test the pressure.

If the aerator is already clean or cleaning it did not help, move to the next step.

Key Takeaways

  • The aerator (screen at the faucet tip) is the most common cause of low pressure in one sink and takes two minutes to clean.
  • Mineral deposits and debris block the aerator screen; vinegar soak and a toothbrush usually clear them.
  • If one sink has low pressure but others do not, the problem is in the faucet itself, not your main water line.
  • Shut-off valves under the sink can get stuck or partially closed; turning them fully open often restores pressure.
  • If pressure is low everywhere in your home, the issue is in your main supply line or meter, and you need to contact your water company.

Check the shut-off valves under the sink

Below your sink are two shut-off valves — one for hot water, one for cold. These are small knobs or levers on the pipes coming from the wall. Over time they can get stuck or someone may have closed them partially without realizing it.

Turn both valves fully counterclockwise (or pull levers all the way out if yours are lever-type). Turn slowly and stop if you feel strong resistance — forcing a stuck valve can break it. Once both are fully open, test the pressure at your sink. If pressure jumps back to normal, a partially closed valve was the problem. If pressure is still low, both valves are open, move to the next step.

Flush the supply lines to clear sediment

Sediment can build up inside the flexible supply lines that connect the shut-off valves to your faucet. This is especially common in older homes or after work on the water main. Flushing the lines often clears the blockage.

Turn off both shut-off valves (turn clockwise). Disconnect the supply lines from the faucet by unscrewing the nuts where they attach — you may see a small amount of water drip out. Place a bucket underneath. Turn the shut-off valves back on for 10 to 15 seconds to let water flush through the open lines into the bucket, then turn them off again. This pushes out sediment. Reconnect the supply lines, turn the valves back on, and test pressure. If this does not work, the problem is inside the faucet body itself.

Replace the faucet cartridge or valve

If the aerator is clean, shut-off valves are open, and supply lines are flushed, the restriction is inside the faucet. Most kitchen faucets use a cartridge — a removable part that controls water flow and temperature. Cartridges can wear out or develop internal blockages.

The steps vary by faucet brand, so look for the model number on the faucet body or underneath the sink, then search online for "[brand] [model] cartridge replacement." Most cartridges cost $20 to $60 and take 15 to 30 minutes to swap. You will need a cartridge puller tool (usually $10 to $15) or you can rent one from a hardware store. If you are not comfortable opening the faucet, a plumber can replace the cartridge in under an hour.

Distinguish between one sink and the whole house

Before you spend time on repairs, figure out whether the problem is only at this sink or everywhere in your home. Low pressure at one sink points to the faucet, aerator, or supply lines. Low pressure everywhere — kitchen, bathroom, outdoor hose — points to your main water line, meter, or water company supply.

If pressure is low everywhere, check with your neighbors to see if they have the same problem. If they do, contact your water company — the issue is on their side of the meter and they will investigate at no cost to you. If only your home is affected, you may have a leak in the main line or a problem at your meter, and you should call a plumber to diagnose.

When to call a plumber

Call a plumber if the aerator is clean, shut-off valves are fully open, supply lines are flushed, and pressure is still low. At that point the problem is inside the faucet body or in the main supply line, and opening the faucet requires tools and knowledge most homeowners do not have. A plumber can diagnose the issue in one visit and replace a cartridge or faucet the same day.

You should also call a plumber if you feel strong resistance when turning a shut-off valve — forcing it can break the valve seat and cause a leak. A plumber can replace a stuck valve without damaging the pipes.

Frequently Asked Questions

Why is pressure low only in my kitchen sink and not the bathroom?

The problem is in the kitchen faucet or its supply lines, not your main water line. Start by cleaning the aerator, then check the shut-off valves under the sink. If both are fully open and the aerator is clean, the cartridge inside the faucet is likely blocked or worn.

Can I clean the cartridge instead of replacing it?

You can try. Turn off the shut-off valves, remove the cartridge (this requires a puller tool), and soak it in white vinegar for one hour to dissolve mineral deposits. Rinse it thoroughly and reinstall. If pressure does not improve, the cartridge is worn and needs replacement.

What if I turn the shut-off valve and nothing happens?

The valve may be stuck. Stop turning and do not force it — forcing can break the valve seat and cause a leak. Leave it as is and move to the next step. If you need to shut off water later, you can turn the main shut-off valve for your whole house (usually near the meter or where the main line enters your home).

How do I know if my supply lines are clogged?

Disconnect them from the faucet and turn on the shut-off valves briefly. If water flows out slowly or with sediment, the lines are clogged. If water flows freely, the lines are clear and the problem is in the faucet itself.

Is low water pressure a sign of a leak?

Not always. A leak usually shows up as wet spots under the sink or in the cabinet. Low pressure without visible water is more often a clogged aerator, stuck valve, or worn cartridge. If you see water pooling, turn off the shut-off valves and call a plumber.