The short answer
Low water pressure at just the kitchen sink in a Northern Virginia house is usually at the faucet, not in the pipes. The common cause is the aerator, the little screen at the tip of the spout, clogged with mineral scale or grit. On a pull-down or pull-out faucet it can be the spray head, or a hose kinked under the sink. Those are ten-minute fixes. If the bathroom sinks and the shower are weak too, it isn’t the faucet. It’s the house’s water pressure, and the usual cause is the pressure reducing valve where the water comes in.
One faucet, or the whole house?
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| What you see | What it usually is | How soon |
|---|---|---|
| The kitchen faucet is weak, everything else is fine | The aerator or the spray head, clogged | Today. Ten minutes. |
| Weak right after water work on the street or in the house | Grit knocked loose and caught in the aerator and the faucet’s cartridge | Today. Clean the aerator. |
| Only the hot side is weak at the kitchen | The faucet’s cartridge, or the hot shutoff under the sink not all the way open | Soon. |
| The side sprayer is weak and the spout is fine | The diverter inside the faucet, or the sprayer hose | When it bugs you. |
| Hot water is weak at every faucet, cold is fine | The valve at the water heater, or a problem at the water heater | Have it looked at. |
| Every faucet in the house is weak | The pressure reducing valve, the main shutoff, or a whole-house filter | This week. Test the pressure. |
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Fix it in this order
- Unscrew the aerator from the tip of the spout. Turn it counterclockwise by hand, or with pliers wrapped in a rag so you don’t scratch the finish. Some faucets hide it inside the spout, and those take the small plastic key that came with the faucet.
- Turn the water on with the aerator off. If it comes out strong, the aerator was the problem.
- Soak the aerator parts in white vinegar for an hour, brush off the scale with an old toothbrush, rinse, and put them back in the same order. If the screen is torn or the scale won’t budge, a new aerator is a few dollars at any hardware store.
- Pull-down or pull-out faucet? Unscrew the spray head from the hose and run the water into a bucket. Strong flow means the spray head is clogged, so clean its screen the same way. Weak flow means the problem is farther back.
- Look under the sink. Make sure the pull-down hose isn’t kinked or snagged on its weight, and that both shutoff valves are all the way open, turned fully counterclockwise. After someone works under a sink, one is sometimes left half closed.
- Check the supply lines from the valves to the faucet for a kink.
- Still weak? Then it’s the cartridge, the valve inside the faucet that mixes hot and cold. Scale and grit clog it, and replacing the cartridge or the faucet is the fix (faucet repair).
Hard water brings it back
Water in much of Northern Virginia leaves white scale on faucets, and that scale is what clogs aerators and cartridges. If you’re cleaning the aerator every few months, the water is the problem, not the faucet (hard water in Northern Virginia). A softener or a scale filter at the main fixes it for every faucet at once (whole-house filter or softener).
When it’s the whole house
Turn on a bathroom sink and the tub. If they’re weak too, test the pressure. A gauge from a hardware store screws onto an outside spigot or the washing machine valve. Normal house pressure is about 40 to 80 psi. Under 40, the usual cause is a pressure reducing valve that’s failing (what a pressure reducing valve does), and replacing one runs $500 to $1,000. Over 80 is a problem of its own: it wears out faucets and supply lines early and can make pipes bang (water hammer).
The other usual causes: the main shutoff left partly closed after work on the house, a whole-house filter cartridge past its change date, or old galvanized supply pipe narrowed with rust inside (low water pressure in the whole house).
When to call
Call when the aerator’s clean and it’s still weak, when one side is weak with the valve under the sink wide open, or when the whole house is low. For one faucet, it’s faucet repair, and you get the price before the work starts. For the whole house, SwiftPro’s whole-house plumbing check is a flat $99: a plumber goes through the valves, the drains and the water pressure and tells you what’s causing it. There’s $50 off any plumbing repair over $400 (every current deal).
Book it
Book the $99 plumbing check. Call (703) 997-9757, or book online from goswiftpro.com/cookiesoffer and a box of warm cookies comes with the visit. Our plumbers work in Vienna, Oakton, McLean, Reston and across Northern Virginia, 24 hours a day. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Questions people ask
Why is the water pressure low in my kitchen sink but fine everywhere else?
Because the problem is in the kitchen faucet: a clogged aerator, a clogged spray head on a pull-down faucet, a kinked hose, a shutoff under the sink left half closed, or a worn cartridge. Start with the aerator.
How do I clean a kitchen faucet aerator?
Unscrew it from the tip of the spout, soak the parts in white vinegar for an hour, brush off the scale, rinse, and screw it back in. Aerators hidden inside the spout need the small key that came with the faucet.
Why is only the hot water low in my kitchen sink?
If it’s only the kitchen, check that the hot shutoff under the sink is all the way open. After that it’s usually the faucet’s cartridge. If hot is weak at every faucet, the problem is at the water heater or its valves.
Why is my pull-down kitchen faucet losing pressure?
The spray head’s screen clogs with scale and grit, or the hose kinks under the sink. Unscrew the head and run the water: if the hose flows strong, clean or replace the head.
What is normal water pressure for a house?
About 40 to 80 psi. Under 40 feels weak, and over 80 is hard on faucets, toilets and supply lines. A pressure reducing valve where the water comes in keeps it in that range.
