How to Fix Low Water Pressure in a Faucet
Updated September 18, 2026
Can I do this myself?
Safe to DIY
Yes, fixing low pressure at a single faucet is safe and usually takes minutes. If the pressure is low everywhere in the house, the cause is likely outside your fixtures and needs a plumber or your water utility.
When one tap/faucet slows to a trickle while the rest of the house flows normally, the problem is almost always at that fixture. The most common culprit is a clogged aerator, the small screen at the tip of the spout that mixes air into the stream. Grit, rust flakes and mineral scale build up on it, especially after work on the water mains or in hard-water areas.
The first thing to figure out is how widespread the problem is. Check the other faucets, the shower and the toilet fill speed. If only one fixture is weak, you can almost certainly fix it yourself. If only the hot side is weak everywhere, the cause is likely at the water heater. If everything in the house is weak, the problem is in the main supply, a pressure regulator or the utility's supply, which is a job for a plumber or your water provider.
This guide works from the quickest fixes (aerator and valves) to the more involved ones (cartridge and supply line), in the order a plumber would check them.
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Signs of the problem
- One faucet flows weakly while others in the house are normal
- The stream sprays sideways, splutters or is uneven
- Flow is weak on hot only, or cold only
- Pressure dropped suddenly after plumbing work or a water supply interruption
- White or green crust around the spout tip
Common causes
Clogged aerator
Most commonThe aerator screen at the spout tip catches sediment, rust and mineral scale. It is by far the most common cause of a weak single faucet, and it takes minutes to clean or replace.
Partly closed shut-off valve
Most commonThe supply valves under the sink may have been partly closed during a repair, or bumped. A valve that is only a quarter open will noticeably cut flow at that faucet.
Blocked cartridge or debris in the valve
SometimesGrit that gets past the supply line can lodge in the faucet cartridge's inlet ports or screens. This often happens after mains work or water heater servicing.
Kinked or failing supply line
SometimesA braided or plastic supply hose that is kinked, crushed by items in the cabinet, or collapsing inside with age restricts flow to one faucet.
Whole-house issue
Less commonIf every fixture is weak, the cause may be a failing pressure-reducing valve, a partly closed main valve, corroded galvanised pipes, a leak in the service line, low municipal supply, or a problem with a storage tank or booster pump. These need a plumber or your water utility.
Safety first: before you start
- Critical:Close the hot and cold shut-off valves under the sink (clockwise) and open the faucet to relieve pressure before removing the cartridge or disconnecting a supply line.
- Plug the sink drain with a stopper or rag so the aerator parts and small screws cannot fall in.
- Let hot water cool before working on the hot side. Water from the heater can scald.
- Wrap the aerator in a cloth or masking tape before gripping it with pliers so you do not scratch the finish.
- Critical:Do not adjust or remove a pressure-reducing valve, water meter or anything on the utility side of the main valve. That work belongs to a licensed plumber or the water provider.
Tools & materials
Tools
- Adjustable pliers or aerator key (some recessed aerators need one)
- Cloth or masking tape
- Old toothbrush
- Small bowl
- Adjustable wrench
- Screwdrivers and Allen (hex) keys for the handle
- Flashlight and bucket
Materials
- White vinegar
- Replacement aerator (matched to thread size: male or female)
- Replacement cartridge, if needed
- Replacement braided supply line, if needed
Step-by-step fix
- 1
Check how widespread the problem is
Run the other faucets and shower in the house, both hot and cold. If only this one faucet is weak, continue. If only hot water is weak everywhere, the water heater may be full of sediment or its valve partly closed. If everything is weak, skip to the call-a-pro section.
- 2
Remove and inspect the aerator
Plug the drain. Unscrew the aerator from the spout tip by hand, turning it clockwise when viewed from above (counter-clockwise when you look up at it from below). If it is stuck, wrap it in cloth and use pliers gently. Some modern aerators are recessed and need a small plastic key that often comes with the faucet.
- 3
Test the flow without the aerator
With the aerator off, turn the faucet on. If the flow is now strong, the aerator was the problem. If the flow is still weak, the restriction is further back in the faucet or supply.
- 4
Clean or replace the aerator
Take the aerator apart, noting the order of the screen, flow restrictor and washer. Rinse out grit, scrub with an old toothbrush and soak the metal parts in white vinegar for 30 minutes to an hour to dissolve scale. Reassemble in the same order and screw it back on hand-tight. If it is badly corroded, replace it with one of the same thread size and flow rating.
- 5
Open the shut-off valves fully
Under the sink, turn each supply valve counter-clockwise until it stops. Some quarter-turn valves are fully open when the handle lines up with the pipe. While you are there, check the supply hoses for kinks or crushing.
Warning: If a valve leaks from its stem or will not turn, do not force it. Old valves can break. Leave it and call a plumber.
- 6
Check the supply line
Shut off the valve, put a bucket under the connection and disconnect the supply hose from the faucet. Point it into the bucket and briefly open the valve. A strong flow means the line is fine and the restriction is in the faucet. A weak flow means the valve or hose is restricted. Replace the braided hose if it looks bulged, kinked or rusty.
- 7
Clean or replace the cartridge
With both valves closed and the faucet opened to relieve pressure, remove the handle and the retaining nut or clip, then pull out the cartridge. Look for grit in the inlet holes or in any small screens at the bottom of the faucet body. Rinse the cartridge and clear debris. If it is worn or the flow is still weak, replace it with an exact match for your faucet model.
- 8
Flush and reassemble
Before refitting the aerator, open the supply valves slowly and run the faucet on hot and cold for a minute to flush loose debris. Then refit the aerator and check for leaks under the sink.
Stuck on a step?
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How to check it's fixed
- The faucet runs with a strong, even stream on both hot and cold
- Flow matches other faucets in the house
- No drips at the supply connections or valves
When to stop and call a professional
- Low pressure affects every faucet and shower in the house
- Hot water pressure is low everywhere (possible water heater sediment or valve issue)
- The shut-off valves are seized, leaking or crumbling
- You have old galvanised steel pipes and pressure has gradually fallen over years
- You notice damp patches, a running water meter with everything off, or unexplained high water use (possible hidden leak)
- Neighbours also have low pressure: contact your water utility
How to prevent it
- Clean aerators every few months, especially in hard-water areas.
- After any mains work or water outage, remove aerators and flush the lines before using the faucets normally.
- Keep the cabinet under the sink organised so supply lines are not crushed or kinked.
- Consider a sediment filter or water softener if you often find grit or heavy scale.
Frequently asked questions
Why is only one faucet in my house low pressure?
Almost always because of something at that faucet: a clogged aerator, a partly closed supply valve, debris in the cartridge, or a kinked supply line. Start by removing and cleaning the aerator.
Why is my hot water pressure low but cold is fine?
If it is only at one faucet, the hot side of the cartridge or hot supply valve is likely blocked. If it is everywhere, sediment in the water heater or a partly closed valve at the heater is more likely. Water heater work is best left to a pro if you are unsure.
Can I remove the flow restrictor from my aerator?
Flow restrictors help meet water efficiency rules in many places, and removing them may not be allowed. If your aerator is clogged, clean or replace it rather than removing the restrictor. A clean restrictor still gives good flow.
What causes sudden low water pressure throughout the house?
Common causes are work on the water mains, a partly closed main valve, a failing pressure-reducing valve, a leak in the supply line, or a problem with a storage tank or pump. Check with neighbours and your water utility first, then call a plumber.
This guide is general information, not professional advice. Homes differ, so follow your product manuals and local codes. If anything looks different from what's described, or you feel unsure, stop and call a qualified professional. In an emergency, leave the area and call your local emergency number.
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