Reasons for Low Water Pressure at Your Sink

Turning on your kitchen or bathroom sink faucet expecting a steady, vigorous stream of water for washing dishes or brushing your teeth, only to be met with a weak trickle is not just inconvenient, but a plumbing problem that requires attention.

Low water pressure from your sink faucet can make daily faucet, cleaning and hygiene tasks difficult. Determining the causes and restoring proper water flow and pressure keeps your plumbing functioning smoothly.

Causes of Low Water Pressure at the Sink

There are several common reasons you may experience a sudden drop in water volume and pressure from your sink faucet:

• Clogged aerator or strainer
• Partially closed shut-off valves
• Old galvanized pipes
• Mineral buildup and corrosion

Clogged Aerator or Strainer

The aerator on the end of your faucet regulates water flow and prevents splashing by mixing air into the stream. Over time, small mineral deposits, sediment and debris can collect in the aerator's flow restrictor and screen, limiting water output.

Likewise, old sinks have a strainer basket in the drain to catch food scraps. A clogged strainer basket also obstructs water flow down the drain, manifesting as back pressure that limits faucet water volume.

Partially Closed Shut-off Valves

Most sinks have hot and cold water shut-off valves under the sink or behind the faucet body. These valves allow you to turn off water to the sink for repairs. If the valves are not fully open, they restrict flow.

Partially closed valves are a common oversight when turning the water back on after plumbing work. Even valves that appear to be in the open position may not be allowing full water flow.

Old Galvanized Pipes

Older homes often have galvanized steel pipes that connect the water supply to sinks. Over decades of use, these pipes corrode and accumulate mineral deposits inside, substantially reducing flow.

Replacing galvanized with copper or PEX piping restores volume and pressure. Repiping an entire house is costly, but just replacing the affected sink's supply lines may resolve low pressure.

Mineral Buildup and Corrosion

Hard water high in mineral content like calcium and magnesium contributes to scale accumulation in pipes and plumbing fixtures. The deposits grow over time, shrinking pipe diameter and impeding water flow.

Likewise, corrosion and rust buildup on the inside of pipes has a similar effect, eventually requiring pipe replacement. Installing a water softener system or whole house filter can help prevent these issues.

Diagnosing the Source of Reduced Sink Water Flow

Determining why your sink's water pressure is low requires a process of elimination to check each potential cause:

• Inspect the sink's aerator and strainer
• Check shut-off valves under the sink
• Test water pressure at other faucets
• Inspect supply lines for leaks or crimps

Check Aerator and Strainer

Unscrew the aerator from the faucet spout and the strainer basket from the sink drain. Rinse both under running water to wash away any visible debris. If the water pressure improves after removing the aerator, it confirms the flow restrictor was clogged. If food particles empty from the strainer, a clogged drain is the culprit.

Inspect Shut-off Valves

Shut-off valves under the sink connecting to the hot and cold supply lines may not be fully open. Try opening them another half or full turn to see if it increases water volume. Older valves are prone to clogging from mineral deposits, requiring replacement.

Test Water Pressure at Other Faucets

Check if other nearby faucets, like the kitchen, bathroom or outside hose bibs, have adequate pressure. Low water flow from all faucets indicates a problem with incoming household water pressure. Call your local water company if they all exhibit low flow.

Check for Leaks or Crimps in Supply Lines

Inspect the exposed water supply tubes and valves under the sink for water leaks. Leaks reduce volume. Also look for kinks and bends in the supply tubes that crimp flow. Straighten or patch any damaged sections of supply line.

Fixing a Clogged Faucet Aerator or Strainer

A clogged aerator or sink strainer basket are easily cleaned to restore full water flow:

• Unscrew aerator and remove debris
• Soak in vinegar and scrub with brush
• Replace strainer screen if damaged
• Reattach aerator when clean

Unscrew Aerator and Remove Debris

Use pliers or a specialized aerator key wrench to unthread the aerator from the faucet spout. Inspect the flow restrictor, screen and other internal components for mineral deposits or sediment. Rinse debris away under running water.

Soak in Vinegar and Scrub with Brush

For stubborn deposits clogging the aerator, soak it in white vinegar overnight to dissolve minerals. Gently scrub with an old toothbrush to dislodge remaining particulates.

Replace Strainer Screen if Damaged

While the strainer basket can be washed in soapy water, the screen itself may be excessively corroded or torn, requiring replacement. Unscrew the strainer from the sink drain and examine the screen.

Reattach Aerator When Clean

Once all debris is cleared from the aerator and strainer components, reassemble and screw the aerator back onto the faucet. Test water flow before using the sink to ensure pressure is restored.

Opening Partially Closed Shut-off Valves

If shut-off valves under the sink are limiting water flow, opening them fully reestablishes full pressure:

• Locate hot and cold water shut-off valves
• Turn valves counterclockwise to open fully
• Test water flow after adjusting valves
• Replace old valves if necessary

Locate Hot and Cold Water Shut-off Valves

The hot and cold water supply lines that run under the sink connect to shut-off valves. These valves allow you to turn off water for repairs. There is one valve for hot and one for cold.

Turn Valves Counterclockwise to Open Fully

Use a wrench or pliers to turn the shut-off valves counterclockwise. Turning beyond what seems fully open gives the valves extra turns to make sure water is unobstructed.

Test Water Flow After Adjusting Valves

After opening the valves further, turn on the faucet to check if water pressure and volume improved. The valves may need additional adjustments or replacement if flow is still lacking.

Replace Old Valves if Necessary

Extremely old shut-off valves with corroded internal components may not completely open. Replacing them restores water flow control when repairs are needed.

Replacing Old Galvanized Pipes

Switching out galvanized supply pipes for new piping restores water pressure:

• Determine scope of galvanized piping replacement
• Consult plumber for repair or repipe project
• Install new copper or PEX piping
• Restore water supply and check pressure