Why Is Water Flow From My Faucet Low?
Low water flow at a faucet is almost always caused by something restricting flow somewhere between the wall and the spout: a limescale-clogged aerator, a valve that isn't fully open, a blocked inline filter, a kinked or degraded supply hose, or a worn cartridge inside the faucet body. Less often, the real cause sits outside the faucet entirely, in low building or municipal water pressure. Working through these causes in order, starting with the aerator, usually finds the culprit in minutes.
Is the Aerator Clogged with Limescale or Debris?
The single most common cause of low flow at a faucet is a clogged aerator, the small mesh screen at the very tip of the spout. Mineral deposits from hard water, along with grit and sediment, build up in its tiny holes over weeks or months, gradually choking off flow until the stream turns weak or uneven. Unscrewing the aerator, soaking it in vinegar or a descaling solution, and brushing out the mesh resolves this in most cases within minutes.
Most aerators unscrew by hand or with pliers wrapped in a cloth to avoid scratching the finish. Soak the aerator in white vinegar, or a store-bought descaler, for 30 to 60 minutes, then scrub the mesh with an old toothbrush or a pin to clear individual holes. If flow is still weak after cleaning, run the faucet without the aerator screwed back on: if flow is strong, the aerator itself was the problem and may need replacing rather than just cleaning.
Are the Supply Valves Fully Open?
Every faucet has shutoff valves, usually under the sink, that can end up partially closed after a repair, a house move, or routine maintenance. A valve left even slightly closed noticeably reduces flow, and if only the hot or only the cold side is affected, that valve is the first place to check. Turning both valves fully counterclockwise, to the open position, often restores flow immediately with no parts needed.
Check the angle stops beneath the sink and, if accessible, the main shutoff for the fixture line. Valves that haven't been touched in years can also seize partway open due to mineral buildup inside the valve body; working the handle back and forth gently can free it. If only one side, hot or cold, runs weak, the problem is almost always isolated to that line's valve or filter, not the faucet itself.
Could an Inline Filter or Screen Be Blocked?
Many faucets and supply lines include a small inline filter or screen at the connection point to catch sediment, rust flakes, or grit before they reach the cartridge. Municipal water main work, recent plumbing repairs, or an older supply line can send debris through the pipes that clogs these screens over time, cutting flow well before it reaches the aerator. These filters are inexpensive and straightforward to remove, rinse, or replace.
Look for a small mesh screen where the supply hose connects to the faucet or shutoff valve; it's easy to miss because it's often hidden inside the fitting. If flow doesn't improve after cleaning the screen, or if it's visibly corroded or crushed, replace it rather than reinstalling it. A damaged screen can also let debris straight through to the cartridge, causing further problems downstream.
Is a Flex Hose Kinked or Deteriorating?
The flexible supply hoses connecting the shutoff valves to the faucet can get kinked in the cramped space under a sink, physically pinching off flow at the bend. Over years, the inner lining of braided hoses can also degrade and collapse inward, narrowing the passage even when the hose looks fine from the outside. Straightening a kink costs nothing; a hose with internal wear needs to be replaced rather than repaired.
Open the cabinet and trace both supply hoses from the valve to the faucet, looking for sharp bends, especially where a hose is squeezed against the cabinet wall or another pipe. If the hose is straight but flow is still weak, disconnect one end and check whether water flows freely from it under pressure; if not, the hose's internal lining has likely narrowed and the hose should be replaced.
Could a Worn Cartridge Be Restricting Flow?
The cartridge is the internal valve, typically a ceramic-disc type in most modern faucets, that controls how water passes through the faucet body. Over years of use, wear, mineral scale inside the cartridge, or tiny cracks can narrow the water's path even when everything upstream, the aerator, valves, and hoses, is clear and functioning. If flow is still low after ruling out the other causes, the cartridge is the most likely remaining culprit and usually needs replacement rather than cleaning.
A failing cartridge often shows other symptoms alongside low flow: a stiff or gritty-feeling handle, drips when the faucet is off, or hot and cold water mixing unevenly. Replacement requires matching the cartridge to the faucet's exact brand and model, since cartridges are not universal; an incorrect one can leak or restrict flow just as much as the worn original did.
Is the Problem Really Building or Municipal Water Pressure?
If every faucet and the shower in the home run weak at the same time, the cause is very likely outside the faucet entirely: a building pressure-boosting pump, a low water tank, or reduced pressure from the municipal supply. In this case, no amount of cleaning or part replacement at the faucet will fix it. Checking whether neighbors or other units in the building have the same complaint is the fastest way to confirm this.
In apartment buildings, a malfunctioning booster pump, a low rooftop tank, or scheduled utility maintenance can drop pressure across every unit at once. If the low flow is isolated to a single faucet while others in the house run normally, the cause is local to that fixture, not the water supply, which points back to the aerator, valve, filter, hose, or cartridge for that faucet specifically.
Should You Clean It Yourself or Call a Plumber?
Cleaning an aerator, checking valves, straightening a hose, and rinsing a visible inline filter are all safe, tool-free tasks most people can do in a few minutes. Cartridge replacement, a suspected blockage inside the wall plumbing, or a pressure issue affecting the whole building are better handled by a licensed plumber or reported to building management. Any sign of leaking, dampness, or discoloration near a connection is worth flagging to a professional early, before it becomes a bigger repair.
As a rule of thumb, if the cause is mineral buildup or loose debris, cleaning solves it; if a part is physically damaged, worn, or collapsed internally, it needs replacing rather than cleaning. If you've worked through the aerator, valves, filter, and hoses without success, that's the point to call a plumber rather than guessing at a cartridge replacement, since an incorrectly matched part can create a leak. If the issue affects multiple units in a building, start with building management rather than a private repair.
Frequently Asked Questions
Why did my faucet suddenly lose water pressure?
A sudden drop usually follows recent plumbing work, a water main repair, or a temporary shutoff in the area, which stirs up debris in the pipes that lodges in the aerator or an inline filter. Unscrewing and cleaning the aerator first usually fixes a sudden change within minutes.
Why is only my hot water weak, while cold water is fine?
When only one side is affected, the cause is almost always specific to that line: a partially closed valve, a clogged filter on that supply line, or a restriction in the water heater itself. Check the hot-side shutoff valve and any filter near the water heater before assuming the faucet is at fault.
I cleaned the aerator and flow is still low. What's next?
Work through the other likely causes in order: confirm both shutoff valves are fully open, check the supply hoses for kinks, and inspect any inline filter for buildup. If all of those check out, a worn cartridge or a building-wide pressure issue is the most likely remaining cause.
Why is water pressure low in my new house or apartment?
In a home you've just moved into, the most common cause is a shutoff valve that was never fully reopened after the previous occupant moved out or a maintenance visit. Sediment that built up while the unit sat unused can also clog aerators quickly once the water runs again.
Does vinegar or descaler damage a faucet finish?
A diluted vinegar soak or a commercial descaler used as directed and rinsed promptly is safe for most aerators and won't damage the faucet body if you only soak the removed aerator, not the whole fixture. Avoid leaving acidic solutions on polished or coated finishes for extended periods.
How do I know if low flow is a building issue and not just my faucet?
Check another faucet or the shower in the same unit, and ask a neighbor or building management whether they're experiencing the same thing. If multiple fixtures or multiple units are affected at once, the cause is upstream of your faucet, most likely the building's pressure system rather than a part that needs cleaning or replacing.
I replaced the cartridge but flow is still low. What went wrong?
This is usually caused by an incompatible cartridge that doesn't match the faucet's exact brand and model, or by trapped air left in the line after the swap. Confirm the replacement part number matches the faucet, then run the water for a minute to clear any air before judging the flow.