If every tap in your home seems fine except one, you probably don’t have a whole-house water-pressure problem. The trouble is usually somewhere inside that faucet: a clogged screen, a partly closed shutoff valve, a blocked supply line, or a worn faucet part. The good news is that several of the most common causes are simple to check, and you can often narrow things down before calling a plumber.
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First, Check Whether It’s Low Pressure or Low Flow
People often say “low water pressure” when they mean the faucet releases less water than usual. The difference matters. Pressure is the force pushing water through the plumbing. Flow is the amount of water that comes out over time.
A faucet can have normal pressure in the pipe but poor flow because something is restricting the water at the outlet. A clogged aerator is a common example: water reaches the faucet, but mineral deposits or debris block the small openings where it exits. From your perspective, the stream looks weak either way, so the best approach is to check the faucet from the outlet backward toward the pipes.
Common Causes of Low Water Pressure in One Faucet
1. A clogged aerator
The aerator is the small fitting at the tip of many faucets. It mixes air into the water and shapes the stream. Because water passes through its fine mesh, bits of mineral scale, rust, or sediment can collect there over time.
If the stream sprays sideways, looks uneven, or has gradually weakened, the aerator is a good first suspect. It’s especially likely if the faucet is used often or your home has hard water. A clog can affect only that faucet because debris may settle in one small screen rather than blocking the plumbing throughout the house.
2. A partly closed or blocked shutoff valve
Most sinks have two small shutoff valves underneath: one for hot water and one for cold. If a valve is not fully open, it limits how much water can reach the faucet. This can happen after plumbing work, a repair, or even an accidental bump while storing cleaning supplies.
A valve can also become restricted inside as it ages. Turning an old, stiff valve too forcefully may cause it to leak or fail, so don’t muscle it. If you can see that a valve is partly closed, turn it gently counterclockwise until it stops. If it resists, drips, or feels brittle, leave it alone and get advice from a plumber.
3. A kinked or clogged supply hose
Flexible hoses connect the shutoff valves to the faucet. If a hose is sharply bent, squeezed against the cabinet, or twisted, water can’t pass through as easily. This is common after someone moves items under the sink or after a faucet has been installed or replaced.
Look at the hoses without pulling on them. They should curve naturally rather than fold over on themselves. A hose can also collect debris or deteriorate internally, even if its outer surface looks fine. If straightening a visible kink doesn’t help, replacing the hose may be needed.
4. A clogged faucet cartridge or valve
Inside many faucets, a cartridge or valve controls the amount and temperature of water. Sediment and mineral deposits can build up inside it, restricting the flow. Wear can cause similar problems, particularly in a faucet that has been used for years.
A cartridge problem may affect both hot and cold water, or just one side. You might also notice a handle that has become stiff, a temperature that’s hard to control, or a faucet that drips. The repair varies by faucet model, so check the manufacturer’s instructions before taking the handle apart. A cartridge that looks similar may still be the wrong fit.
5. A problem with the faucet’s internal screens or spray head
Some faucets have more than one screen or flow-control part. Pull-down kitchen faucets, for example, may have a removable spray head with a small screen inside. Debris can lodge there, or in the hose connection, and reduce flow even when the main faucet body is clear.
If the faucet has a spray setting, compare the regular stream with the spray function. If one works much better than the other, the issue may be in the spray head or diverter rather than in the home’s supply pipes.
6. A local plumbing blockage or leak
Less commonly, a pipe serving that faucet may be blocked by scale, rust, or debris. A leak in the same branch can also reduce the water reaching the faucet, though leaks often leave other clues, such as damp cabinet surfaces, stains, or the sound of running water.
If you find moisture under the sink, don’t assume it’s harmless condensation. Dry the area, run the faucet briefly, and check whether water appears around a connection or hose. A hidden leak or a blockage inside a fixed pipe is a good reason to call a licensed plumber.
Use the Symptoms to Narrow It Down
What you notice | Possible cause | What to check first |
|---|---|---|
Weak, uneven, or spraying stream | Clogged aerator or spray-head screen | Clean the removable screen or spray head |
Only hot or only cold water is weak | One shutoff valve, supply hose, or cartridge side is restricted | Compare the hot and cold flow, then inspect the matching valve and hose |
Flow is weak from both hot and cold | Aerator, faucet cartridge, or shared faucet passage is blocked | Start at the aerator, then check the faucet parts |
Problem began after plumbing work | Partly closed valve or debris moved into the faucet | Check the shutoff valves and clean the aerator |
Other taps are weak too | A wider supply, pressure, or plumbing issue | Check several fixtures and contact your water provider or a plumber if needed |
How to Troubleshoot the Faucet Safely
1. Compare hot and cold water
Turn on cold water, then hot water, and notice whether one side is weaker. If only one side has low flow, you’ve narrowed the search to that side’s shutoff valve, supply hose, or the corresponding part of the faucet cartridge. If both sides are weak, the aerator or a shared faucet component is more likely.
2. Remove and clean the aerator
Protect the faucet finish with a cloth, then unscrew the aerator by hand if possible. If it’s stuck, use a tool carefully and pad the surface to avoid scratches. Keep track of the order of the small pieces so you can put them back correctly.
Rinse the screen and remove loose particles with a soft brush. If mineral scale remains, soak the removable parts in white vinegar, then rinse them thoroughly. Don’t soak decorative or delicate faucet parts unless the manufacturer says it’s safe. With the aerator removed, briefly run the faucet into a bowl or sink. If the flow is strong now, the clog was likely in the aerator. Keep a hand over the opening or use a container, since the stream may splash.
3. Check the shutoff valves and hoses
Look beneath the sink for the hot and cold valves. Check that neither is obviously turned partly off, and inspect the hoses for sharp bends or pinches. If a valve moves freely and appears partly closed, open it gently. Don’t force a stuck valve, and watch for drips afterward.
If the hose looks damaged, leaks, or remains restricted after you correct a kink, it may need replacement. Replacing a supply line means shutting off the water and making secure connections. If you’re unsure how to do that, a plumber can handle it quickly and help prevent water damage.
4. Check the faucet model before opening it
If cleaning the aerator and checking the supply don’t solve the issue, the cartridge or another internal part may need attention. Find the faucet’s brand and model if you can. The manufacturer’s guide can show how to remove the handle, where the cartridge is located, and which replacement part fits.
Before disassembly, shut off both water valves under the sink and open the faucet to release pressure. Put a plug or cloth over the drain so small screws don’t disappear. If the faucet is old, the parts are corroded, or you can’t shut off the water reliably, it’s safer to stop and call a plumber.
When the Problem May Be Bigger Than One Faucet
Run water at a few other fixtures. If they all have normal flow, the issue is probably local to the faucet. If several taps have weakened, or the pressure changed suddenly throughout the home, look beyond that one fixture.
A whole-home problem could involve a main shutoff valve that isn’t fully open, work on the water supply, a pressure-reducing valve, or an issue on the utility’s side. Ask a neighbor whether they’re experiencing the same problem, and contact your water provider if the change is sudden or affects the neighborhood. If only your home is affected, a plumber can check the main supply and pressure-regulating equipment.
How to Help Prevent Low Flow
Clean faucet screens periodically. If you have hard water or notice scale, checking the aerator every few months can prevent buildup from becoming a stubborn blockage.
Keep the area under the sink clear. Stored items can press on hoses or knock shutoff valves partly closed.
Watch for early changes. A stream that becomes uneven over several weeks may be easier to fix than a faucet that stops flowing well altogether.
Use the right replacement parts. A cartridge or aerator designed for your faucet is more likely to restore normal flow without causing leaks or poor temperature control.
Read more related posts:
- 10 causes of low water pressure in bathroom showers what to do
- Rainfall Shower Head for Low Water Pressure: Fix Your Flow
- Why Is the Water in My Toilet Low: Simple Fixes That Work
Frequently Asked Questions
Why is only one faucet in my house running slowly?
A restriction near that faucet is the likeliest reason. Check its aerator, shutoff valves, supply hoses, and cartridge before assuming there’s a problem with the home’s main water supply.
Can a clogged aerator make water pressure seem low?
Yes. The aerator can restrict the water leaving the faucet, making the stream look weak even when the supply pressure is normal. Removing and cleaning it is a simple first test.
Why is the hot water weaker than the cold at one faucet?
The hot-side shutoff valve or supply hose may be restricted, or debris may be affecting one side of the faucet cartridge. If other faucets have normal hot water, the issue is probably local to that fixture.
Should I replace the faucet if cleaning it doesn’t help?
Not necessarily. A worn cartridge, blocked hose, or faulty shutoff valve may be repairable. Check the faucet model and the condition of its parts; replacement makes more sense when the faucet is badly corroded, repeatedly failing, or difficult to repair.
Conclusion
When just one faucet has low water pressure, start with the simplest explanations: a clogged aerator, a partly closed valve, or a bent supply hose. Compare hot and cold flow, clean the faucet screen, and inspect the connections under the sink. If those checks don’t restore the stream—or you find a leak, damaged valve, or stubborn internal blockage—bring in a plumber rather than forcing old parts.
