Why Does My Kitchen Faucet Have Low Water Pressure?

When the kitchen faucet trickles but the bathroom faucets run fine, the problem is almost never your home’s water pressure — it is something choking flow at that one fixture. In most cases the culprit is a clogged aerator (the little mesh screen at the tip of the spout), and the fix takes five minutes with no tools. Work through these checks in order, from easiest to hardest.

Quick diagnosis: isolate the problem

• Only the kitchen faucet is weak (hot and cold both) → clogged aerator or blocked faucet supply lines. Start with Step 1.
• Only the hot water is weak at the kitchen sink → the problem is on the hot side: check the hot supply valve under the sink, or sediment in the water heater. See Step 3.
• All faucets in the house are weak → this is a whole-house issue (main shutoff partially closed, pressure regulator failing, or a municipal supply problem). Skip to the whole-house section.
• Pressure starts strong then fades → a flow restrictor or cartridge issue inside the faucet, or a kinked supply line. See Step 4.

What you will need

• Adjustable wrench or channel-lock pliers
• Old toothbrush
• Small bowl + white vinegar
• Towels and a small bucket
• Plumber’s tape (Teflon tape)
• Optional: a pressure gauge that screws onto a hose bib ($10)

Step 1: Clean the aerator (fixes most cases)

The aerator mixes air into the water stream — and its fine mesh screen catches every bit of sediment, mineral scale, and debris in your water. When it clogs, flow drops dramatically.

1. Unscrew the aerator. It is the small cap at the very tip of the faucet spout. Most unscrew by hand (counterclockwise looking up). If it is stuck, wrap a cloth around it (to protect the finish) and use pliers gently.
2. Note the order of parts. Tip the parts out onto a towel in order: rubber washer, mesh screens, flow restrictor, housing. You will reassemble in reverse.
3. Turn the faucet on briefly with the aerator off, holding a cup over the spout — this flushes loose debris out of the spout. You will often see grit spit out; that grit was your problem.
4. Soak the parts. Drop the screens and housing into a bowl of white vinegar for 30–60 minutes to dissolve mineral scale. Scrub with the old toothbrush afterward.
5. Reassemble and test. Put the parts back in the same order, screw the aerator on hand-tight (plus a tiny snug with the cloth-and-pliers if it drips at the threads), and run the water. In the majority of cases, full pressure is back.

If the aerator is corroded beyond cleaning, replacements cost $3–$8 at any hardware store. Bring the old one to match the thread size (most are 15/16-inch male or 55/64-inch female — the two standard US sizes).

Step 2: Check the supply valves under the sink

If the aerator is clean and pressure is still low, look under the sink. Each faucet has two supply valves (hot and cold) where the supply lines meet the wall or floor pipes.

1. Make sure both valves are fully open. Turn each counterclockwise until it stops. Valves get bumped half-closed during cleaning or past plumbing work — it happens more often than you would think.
2. If a valve is stuck or crusty, do not force it (old gate valves snap). Turn it gently; if it will not budge, that valve may need replacing — a 30-minute job for a plumber, or a confident DIYer with the main water shut off.
3. Check the supply lines themselves for kinks — flexible braided lines can get pinched when things are shoved under the sink.

Step 3: Hot-water-only pressure loss

When only the hot side trickles:

1. Check the water heater’s shutoff valve — make sure it is fully open.
2. Sediment in the water heater is the usual suspect, especially with hard water. Sediment collects at the tank bottom and gets drawn into the hot lines. Flushing the water heater once a year prevents this (attach a hose to the drain valve, run it to a floor drain, and flush until the water runs clear).
3. Check the faucet’s hot supply line for a clogged inlet screen — some faucets have small screens where the supply lines connect to the faucet body. Shut the valves, disconnect the line, and rinse the screen.

Step 4: Clean or replace the faucet cartridge

If pressure is low on both hot and cold and everything above checks out, debris may be lodged in the faucet cartridge (the internal valve that mixes hot and cold).

1. Shut off both supply valves under the sink and open the faucet to release pressure.
2. Remove the handle (usually a small Allen screw or a cap covering a Phillips screw), then unscrew the retaining nut and pull the cartridge straight out.
3. Rinse the cartridge under running water and pick out any grit from its inlet ports with a toothpick. Soak in vinegar if scale is visible.
4. Reinstall (or replace — cartridges run $15–$40; bring the old one to match) and test.

Whole-house low pressure

If every fixture is weak, the problem is upstream of any single faucet:

1. Check the main shutoff valve (where water enters the house, often near the water meter or in the basement). Make sure it is fully open — a valve left half-open after plumbing work throttles the whole house.
2. Test with a pressure gauge. Screw a $10 gauge onto an outdoor hose bib. Normal residential pressure is 40–80 psi. Below 40, something is wrong; above 80, you have a different problem (and need a regulator).
3. Find the pressure regulator (a bell-shaped device on the main line, usually near the shutoff). These fail after 10–15 years. A plumber can test and replace it — this is not a beginner DIY job since it involves the main line.
4. Ask a neighbor. If their pressure is also low, it is a municipal supply issue — call the water utility.

What this costs

Mistakes to avoid

• Scratching the faucet finish with bare pliers. Always wrap the aerator in a cloth first. A scratched chrome spout is a permanent eyesore.
• Losing the aerator parts order. The screens, restrictor, and washer only work stacked correctly. Lay them out in order on a towel as they come out.
• Overtightening the aerator. Hand-tight plus a hair more. Cranking it with pliers deforms the washer and can crack the housing.
• Forcing a stuck supply valve. Old valves break off in your hand and then you have water spraying under the sink. Gentle pressure only; replace stubborn ones with the main water off.
• Ignoring the hot-side-only pattern. That pattern points at the water heater or hot supply — cleaning the aerator twice will not fix it.

Keeping the pressure up

• Clean aerators once a year — it takes five minutes and prevents the slow decline you stop noticing.
• If you have hard water, a whole-house sediment filter ($50–$150) catches the grit before it reaches your faucets and appliances.
• Flush the water heater annually to keep sediment out of the hot lines.

Frequently asked questions

Why is my kitchen faucet pressure low but the bathroom is fine? Because the restriction is at that fixture — almost always the aerator. Whole-house problems affect every faucet equally. One weak faucet means one local clog.

Can a clogged aerator affect only hot or only cold water? No — the aerator is downstream of where hot and cold mix, so it affects both equally. If only one side is weak, the blockage is upstream: supply valve, supply line screen, or (hot side) the water heater.

How do I know if my water pressure is actually low or just feels low? Screw a pressure gauge onto the outdoor hose bib. 40–80 psi is normal. Modern faucets also have flow restrictors (max 1.8–2.2 gallons per minute by law), so a new faucet can feel weaker than a 1990s one even at perfect pressure — that is by design, not a defect.

The aerator is clean but pressure is still low. What next? Check the under-sink supply valves (fully open?), then the faucet cartridge for debris. If hot-only, look at the water heater. Work the list in order — each step eliminates one suspect.

When to call a plumber

• A supply valve that will not turn or starts leaking when you touch it — old valves fail, and replacing one means shutting off the main.
• Pressure below 40 psi at the hose bib with the main valve fully open — likely a failing pressure regulator or a supply-line problem.
• Galvanized steel pipes (common pre-1970): they corrode from the inside, and low pressure at multiple fixtures often means the pipes themselves are closing up. Repiping is a pro job.
• Any sign of a leak you uncover while working under the sink — water stains, mold, or a musty smell deserve professional eyes.