There is nothing more frustrating than standing at the sink waiting for a pot to fill or your hands to rinse while water trickles out at the speed of a leaky garden hose. Low water pressure in a faucet is a common problem with a clear list of causes. Most of them are fixable in minutes. Some require a bit more work. And a few point to larger issues in your home’s plumbing that need professional attention.
First: Determine If It Is One Faucet or All of Them
Before diagnosing anything, check other faucets in your home. If the problem is in only one faucet, the issue is localized — likely a clogged aerator, partially closed shut-off valve, or supply line issue specific to that fixture. If multiple faucets in one room are affected, the issue may be with the supply lines to that area or a zone shut-off valve. If pressure is low throughout the whole house, this points to a main supply problem — your pressure regulator, the main shut-off valve, or an issue with your municipal water supply. Narrowing this down first saves significant time and effort.
Cause 1: Clogged Aerator (Most Common)
The aerator is the small mesh screen at the tip of your faucet. It mixes air into the water stream to create a smooth, splash-free flow. Over time, mineral deposits and sediment accumulate in the mesh and reduce water flow significantly. This is by far the most common cause of low pressure in a single faucet.
How to fix it: Unscrew the aerator counterclockwise (wrap with tape and use pliers if needed). Disassemble it — housing, screen, and flow restrictor. Soak in white vinegar for 30 to 60 minutes. Scrub with an old toothbrush to remove loosened deposits. Rinse and reassemble. Reinstall and test. If the aerator is badly corroded, replace it entirely — they are $3 to $10 at hardware stores. Regular aerator cleaning is also covered in our faucet maintenance guide.
Cause 2: Partially Closed Shut-Off Valve
The shut-off valves under your sink control water supply to that fixture. If one is partially closed — even slightly — it restricts flow and reduces pressure. Shut-off valves can get nudged partially closed when you are storing cleaning products under the sink or during any plumbing work.
How to fix it: Turn the shut-off valves counterclockwise until fully open. They should turn freely and stop when fully open (do not force them past that point). Check both the hot and cold valves — a partially closed hot valve will only affect hot water pressure.
Cause 3: Kinked or Restricted Supply Line
Supply lines (the flexible hoses connecting shut-off valves to the faucet) can kink if they are bent at a sharp angle or if something is pressing against them inside the cabinet. A kinked supply line can reduce pressure dramatically — sometimes to nearly nothing.
How to fix it: Open the cabinet and inspect the supply lines visually. They should curve gently without sharp bends. Rearrange any stored items pressing against them. If a line is permanently kinked or creased, replace it — they cost $5 to $15 and take five minutes to swap out. Our tools guide covers what you need for supply line replacement.
Cause 4: Clogged Cartridge or Valve Body
Mineral deposits do not just clog aerators — they build up inside the faucet’s cartridge or valve body too, especially in homes with hard water. This internal clogging restricts flow at the source.
Signs this is the cause: Cleaning the aerator did not improve pressure; shut-off valves are fully open; the faucet has been in service for many years without internal maintenance.
How to fix it: Remove the handle and cartridge. Soak the cartridge in white vinegar for several hours. Rinse it out and inspect the interior of the faucet body (use a flashlight). Flush the faucet body by briefly turning the water on with the cartridge removed (have a bucket ready). Reinstall the cleaned cartridge or replace it if heavily scaled. Cartridge removal steps are covered in detail in our faucet leak guide.
Cause 5: Pressure-Reducing Valve Set Too Low
Most homes have a pressure-reducing valve (PRV) where the main water line enters the house. If the PRV is set too low, or if it is aging and failing, it can reduce household pressure below comfortable levels.
How to diagnose: Purchase an inexpensive water pressure gauge ($10–$15) and attach it to an outdoor hose bib. Normal pressure should be 40 to 60 PSI.
How to fix it: The PRV has an adjustment screw on top. Turning it clockwise increases pressure. Make small adjustments and retest. If the PRV is failing and will not hold proper pressure, it needs replacement — a job for a plumber. Managing pressure well is also important for water efficiency — see our eco-friendly plumbing guide.
Cause 6: Hot Water Only Pressure Is Low?
If only your hot water pressure is low, check the hot water shut-off valve under the sink specifically — it may be partially closed. Also check your water heater. Sediment buildup inside a water heater can restrict flow. Flushing the water heater annually helps prevent this.
Cause 7: Main Shut-Off Valve Partially Closed
If pressure is low throughout the entire house, the main shut-off valve (usually located near the water meter) may be partially closed. This sometimes happens after plumbing repairs when the valve was not fully reopened.
How to fix it: Locate the main shut-off valve and ensure it is fully open. Turn counterclockwise until it stops. Ball valves should be parallel to the pipe when fully open; gate valves should turn counterclockwise until they stop.
Quick Diagnosis Checklist
Work through this list in order — each step rules out the most common causes first:
- Clean the aerator
- Check both shut-off valves are fully open
- Inspect supply lines for kinks
- Check if pressure is low at other faucets too
- Test whole-house pressure with a gauge
- Check PRV setting
- Verify main shut-off valve is fully open
- Call water utility if problem is widespread and sudden
Frequently Asked Questions
What is considered normal water pressure for a home faucet? Normal household water pressure runs between 40 and 60 PSI. Below 40 PSI feels noticeably weak. Below 20 PSI is considered very low and significantly impacts usability. Above 80 PSI is too high and can damage faucets and appliances.
Will a new faucet improve my water pressure? Only if the current faucet has internal clogging or a restrictive flow design. The best new faucet cannot compensate for low supply pressure — if the pressure at the shut-off valve is low, the faucet downstream will be low too. Our durability buying guide explains what to look for in a faucet for maximum flow performance.
Can a flow restrictor cause low pressure? Yes. Many new faucets and aerators include a flow restrictor to comply with water conservation standards. You can remove it to increase flow — locate the small rubber disc inside the aerator and pull it out. Note that this will increase water usage. For the balance between pressure and conservation, read our water-saving faucets guide.
My pressure is fine in the morning but low in the evening. What is causing this? This pattern typically indicates a municipal supply issue or very high neighborhood demand during evening hours. Contact your water utility to report it.
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