Quick answer
A faucet aerator is the small screw-in or screw-on insert at the tip of a faucet spout that mixes air into the water or straightens it, filters out grit with a screen, and limits how many gallons per minute the faucet can deliver.
Its printed gpm rating usually sets the faucet’s real flow. Federal rules cap replacement aerators at 2.2 gpm at 60 psi, and WaterSense labeled bathroom models at 1.5 gpm.
Quick facts
The key facts about Faucet Aerator, with sources:
Key takeaways
- The aerator is the part that decides most faucets’ flow rate; the number is often printed on its side.
- Federal rules cap faucets and replacement aerators at 2.2 gpm at 60 psi; WaterSense bathroom models top out at 1.5 gpm.
- A weak or sputtering stream at one tap is very often a clogged aerator screen, not a pipe problem.
- Cleaning or swapping an aerator is one of the few plumbing jobs most homeowners can do with no tools or a small key.
- After water main or service line work, the screen can trap debris, including lead particles in older systems, so clean it.
What a faucet aerator is and the three jobs it does
Look at the very end of a kitchen or bathroom faucet spout. The round metal or plastic piece that unscrews from the tip is the aerator. Some sit inside the spout and need a small plastic key to remove; these are called hidden or cache aerators.
An aerator does three jobs. It breaks the water into many small streams and pulls in air, so the flow feels full and splashes less.
It holds one or more fine screens that catch grit and scale. And it has a built-in restrictor that sets the maximum flow in gallons per minute (gpm).
Federal rules treat the aerator as part of the faucet: the same 2.2 gpm cap at 60 psi applies to lavatory faucets, kitchen faucets and the replacement aerators sold for them 1.
The product standard behind all of this is ASME A112.18.1/CSA B125.1, which covers plumbing supply fittings. It treats an aerator as an accessory: a part a user can add, remove or replace without stopping the faucet from working 4. That is why you can change your flow rate by changing a two-inch part.
Aerator vs. cartridge
The aerator controls how the water leaves the spout. The faucet cartridge inside the handle controls whether water flows and how hot it is. A drip from the spout with the handle off is a cartridge problem; a weak, spraying stream with the handle wide open usually starts at the aerator.
How water moves through an aerator to the sink
Most aerators follow the same path from the spout to the sink, even though the parts inside vary by maker.
- Water leaves the spout at whatever pressure your home has. Many homes sit well above the 20 psi low-pressure test point WaterSense uses 3.
- The restrictor limits flow. A small disc or regulator inside caps the gpm. Its rating is what the federal and WaterSense limits measure 12.
- Screens catch debris. Fine mesh or a honeycomb grid traps sand, scale and pipe debris. EPA notes aerators have a screen to collect particles and sediment 5.
- Air is drawn in. In an aerated model, side openings pull air into the stream, which softens it. A laminar model skips the air and sends out clear, straight streams.
- A shaped stream exits. You get an aerated, laminar or spray pattern, at a flow no higher than the rating.
- Threaded housingMale or female threads, or a hidden insert
- Flow restrictorSets the gpm rating
- Upper screenCatches grit and scale
- Mixing chamberDraws in air on aerated models
- Outlet screen or gridShapes the final stream
Layer order varies by maker; the restrictor and screens are what clog and what set flow. Source: [4] [5]
Which aerator types exist and what stream each gives
| Type | What the stream looks like | Good fit | Watch for |
|---|---|---|---|
| Aerated | White, soft, air-filled stream | Most bathroom and kitchen sinks | Can mist slightly; screens clog |
| Laminar | Clear, straight streams with no air | Places where airborne spray is unwanted | Fills containers with less splash; still clogs |
| Spray | Many fine jets | Low-flow bathroom faucets | Can feel weak for filling pots |
| Hidden (cache) | Any of the above, inside the spout | Modern designer faucets | Needs the right plastic key to remove |
| Swivel or dual-spray | Adjustable direction or pattern | Kitchen sinks without a pull-down sprayer | More joints that can leak |
Example: measuring your faucet’s flow with a 10-second fill
EPA’s WaterSense home checklist uses a simple timed fill to verify a 1.5 gpm bathroom faucet: no more than 0.25 gallon (32 ounces) collected over 10 seconds 3. You can run the same math at home with a measuring cup and a phone timer.
| Water caught in 10 seconds | Math | Flow rate | What it tells you |
|---|---|---|---|
| 0.25 gallon (32 oz) | 0.25 × 6 | 1.5 gpm | Matches the WaterSense maximum 3 |
| 0.37 gallon (about 47 oz) | 0.37 × 6 | About 2.2 gpm | At the federal cap 1 |
| 0.20 gallon (about 26 oz) | 0.20 × 6 | 1.2 gpm | A common lower-flow rating 3 |
| 0.08 gallon (about 11 oz) | 0.08 × 6 | About 0.5 gpm | Public restroom range; low for home use 2 |
Flow (gpm) = gallons caught ÷ seconds × 60
gallons caught- 128 ounces = 1 gallon
seconds- Length of the timed fill, such as 10
Open the handle fully. Test hot and cold separately if the faucet has two supplies.
Source: [3]
Worked check: a bathroom tap labeled 1.5 gpm fills only 12 ounces in 10 seconds (about 0.09 gallon, so roughly 0.6 gpm).
That is well under the label, which points to a clogged screen or low pressure, not to the aerator rating. Clean it and test again.
To test the house as a whole, read the pressure at a hose bib with a gauge.
Where aerators are fitted and where the rating is printed
Every modern bathroom and kitchen faucet has one, unless the spout is a pull-down sprayer head, which has its own built-in flow control. Utility tubs and outdoor hose faucets usually do not. ASME A112.18.1 lists separate flow rules for lawn and sediment faucets, laundry tubs and service sinks 4.
The flow rating is usually stamped on the side of the aerator, sometimes in tiny print like “1.5 GPM” or “5.7 L/min.” WaterSense tells home inspectors to check the gpm marking on the faucet or the aerator 3.
A WaterSense label on the box means the model is independently certified for flow and performance 3.
On a plumber’s invoice, aerators often appear as a small line under fixture installation or a faucet repair. Utilities and water conservation programs sometimes hand them out, since they are cheap and quick to fit.
Before you buy a replacement, run through the checklist below with the old aerator in your hand; most wrong purchases come from a thread mismatch, not a wrong flow rate.
- Threads on the outside (male) or inside (female) of the old part
- Thread diameter matched, or the old part taken to the store
- Hidden (cache) type: the faucet maker’s size and key
- Flow rating stamped on the side, such as 1.5 GPM 3
- Bathroom sink: WaterSense label, 1.5 gpm or lower 2
- Kitchen sink: no more than the 2.2 gpm federal cap 1
What an aerator saves and what it can cost you
What a good aerator does
- Cuts water use: WaterSense says swapping older faucets and aerators can save the average family 700 gallons a year 2.
- Saves hot water energy, since less hot water goes down the drain 2.
- Less splashing and a softer stream at the same pressure.
- Catches grit before it reaches your cup or toothbrush 5.
- Costs very little and installs by hand or with a small key 2.
What it can cost you
- Low-flow models fill pots and buckets more slowly.
- Screens clog, so flow drops over time in hard or gritty water.
- Very low flow makes hot water take longer to arrive. WaterSense warns 0.5 gpm models are generally too low for home bathrooms 3.
- Hidden aerators need a matching key; a lost key makes cleaning harder.
- Thread sizes differ, so a new one may not fit without an adapter.
What an aerator will not fix
An aerator limits flow. It cannot add any. If pressure in the whole house is low, a new aerator will make the problem feel worse, not better.
Check pressure at a hose bib first: psi is the push in the pipes, while gpm is how much water comes out, and an aerator only touches the second.
An aerator screen is not a water filter. It stops visible grit, not dissolved metals, bacteria or chemicals. For those, look at certified point-of-use treatment, such as a carbon filter tested to an NSF/ANSI standard, or our water treatment service.
It also cannot stop a leak. A drip from the spout with the handle closed is a worn cartridge or seat, and a leak under the sink is a supply line or drain connection.
What drives the cost of an aerator job
We do not list prices; fair numbers need dated local quotes. WaterSense describes a new aerator as costing “as little as a few dollars,” which is why this is mostly a do-it-yourself part 2.
What changes the bill: whether the aerator is standard or a branded hidden type that only the faucet maker sells, whether threads are stripped or seized with scale, whether a matching finish is needed, and whether the real problem turns out to be the cartridge or the supply valves.
If a plumber is already on site for other work, an aerator swap adds little. For how full faucet jobs are priced, see our plumbing cost guide.
Aerators do not carry a set lifespan in any federal source we found. They last until the threads wear or scale makes cleaning pointless. The faucet’s own warranty sometimes covers the original aerator; check the maker’s terms.
How to clean or replace a faucet aerator
This is a homeowner job. No permit is involved. Close the sink drain first so small parts cannot fall in.
- Unscrew it. Turn the aerator counterclockwise by hand. Wrap it in a cloth before using pliers so the finish is not scratched. Hidden aerators need their key.
- Note the order. Lay out the washer, screens and insert in the order they came out, or take a phone photo.
- Rinse the debris. EPA’s instruction is simple: unscrew the aerator and remove any debris that has collected there 5.
- Soak off scale. Mineral crust comes off in a short vinegar soak; scrub with an old toothbrush, then rinse well.
- Flush the line. With the aerator off, run the faucet for a moment to push out loose grit.
- Reassemble and test. Hand-tighten, then run the 10-second bucket test above to confirm flow.
- Buy the right replacement. Take the old one to the store, or match thread type (male or female), size and gpm. Choose a WaterSense label for bathroom sinks 2.
How often to clean aerators and why
- Clean aerators on a regular schedule; ask your water supplier how often it recommends for your system.
- Clean right after any water main break, meter swap, or service line work nearby, when debris is most likely.
- In hard water areas, scale builds faster. Our water hardness tool shows how hard your water is.
- During EPA’s 2016 response in Flint, the agency told residents to clean aerators once a week until the system recovered 5. That was an emergency setting, but it shows how fast screens can load up.
- Keep the hidden-aerator key in a drawer near the sink.
One slow tap or every tap?
If one faucet is weak and the rest are fine, start with its aerator. If every fixture is weak, the cause is upstream: the main valve, a pressure-reducing valve or the supply pipes.
Which faucet flow problems need a plumber
- Flow stays weak after a clean aerator and a flush: look at the cartridge, the stop valves or the supply line.
- Black, orange or green flakes keep showing up in the screen: that can be pipe corrosion or failing fittings.
- Gritty debris returns within days of cleaning, which can point to a failing water heater dip tube or pipe scale.
- The aerator threads are cracked or the spout leaks around them.
- Low pressure at every fixture, or pressure that swings.
Debris after pipe work in older homes
When a lead service line or old galvanized pipe is disturbed, particles can lodge in the aerator screen. EPA has told residents in affected systems to clean aerators to remove trapped particles 5.
Do not test or drink from a tap with a visibly dirty screen; clean it, flush the line, and follow your utility’s lead guidance. Ask your utility how to get water tested.
A plumber can trace a debris or pressure problem through the whole system. Our leak detection and repair team covers hidden leaks that also cut flow.
Which federal and EPA rules set aerator flow
Federal (U.S. DOE), 10 CFR 430.32(o): lavatory faucets, lavatory replacement aerators, kitchen faucets and kitchen replacement aerators may not exceed 2.2 gpm (8.3 L/min) at a flowing pressure of 60 psi, for products made after January 1, 1994. Metering faucets are limited to 0.25 gallon per cycle 1.
EPA WaterSense High-Efficiency Lavatory Faucet Specification (released October 1, 2007): labeled bathroom faucets and accessories, including aerators, flow no more than 1.5 gpm at 60 psi and no less than 0.8 gpm at 20 psi. Kitchen and public lavatory faucets are outside its scope 43.
Proposed changes: EPA’s March 2024 Notice of Intent considered lowering the maximum to 1.2 or 1.0 gpm and adding kitchen faucets 4. A December 2024 draft Version 2.0 proposed 1.2 gpm, but a February 2025 EPA note says work on it is paused 2. Treat 1.5 gpm as current until EPA says otherwise.
State rules: EPA notes several states require 1.5 gpm or less on private bathroom faucets, and four states set 1.2 gpm 4. Check your state’s appliance rules before buying for a remodel.
Product standards: ASME A112.18.1/CSA B125.1 sets the test method and lead-free life-cycle rules; WaterSense also points to NSF/ANSI 61 for drinking water components 43.
How an aerator compares with the cartridge, PRV and filters
| Part | Where it sits | What it controls | Main difference |
|---|---|---|---|
| Faucet aerator | Tip of the spout | Stream shape and max gpm 1 | Removable, cheap, easy to clean |
| Faucet cartridge | Inside the handle body | On, off and mix of hot and cold | Fixes drips, not stream shape |
| Showerhead flow restrictor | Inside the showerhead | Shower gpm; federal cap 2.5 gpm at 80 psi 1 | Different limit and test pressure |
| Pressure-reducing valve | Where water enters the house | Pressure (psi) for every fixture | Lowers pressure; aerator only caps flow |
| Sediment filter | On the main line or under a sink | Removes particles before fixtures | Protects all taps, not one |
What people get wrong about aerators
- Myth Lower gpm means lower water pressure.
- Reality Flow and pressure are different. A 1.5 gpm aerator lets out less water at the same psi; WaterSense still requires 0.8 gpm at 20 psi 3.
- Myth The lowest-flow aerator is always the greenest choice for a home.
- Reality EPA says 0.5 gpm models are meant for public restrooms and generally do not give enough flow at home 3.
- Myth A weak faucet means the pipes are failing.
- Reality A clogged aerator screen is the first thing to check; EPA notes the screen collects particles and sediment 5.
- Myth Aerators are not regulated.
- Reality Replacement aerators carry the same 2.2 gpm federal cap as the faucet 1.
- Myth The aerator screen filters the water.
- Reality It stops visible grit only; it is not certified to remove dissolved contaminants.
How your state and your water change aerator choice
Two things vary by where you live. First, the legal flow cap: the federal ceiling is 2.2 gpm, but EPA reports four states set 1.2 gpm for private bathroom faucets 4, so a store in one of those states may not stock higher-flow aerators.
Second, water hardness: in hard water regions, mineral scale clogs aerator screens faster, so cleaning moves from an every-few-months job to a frequent one.
Private wells can also carry sand that loads screens quickly, and wells often run at lower pressure, which is why WaterSense kept a 0.8 gpm minimum at 20 psi 23.
When the aerator matters to you and what to try first
It matters when one tap turns weak or sputters, when you are cutting water and hot-water use, after water main or service line work, and when you buy faucets for a remodel in a state with a lower cap.
The next step is usually free: unscrew it, clean it, and time a fill. If flow is still low, or debris keeps coming back, a plumber should check the valves and pipes behind the wall.
- If One faucet sputters or sprays sideways
- Then Clean the screens and remove scale 5
- If Flow is fine but you want to save water at the bathroom sink
- Then Fit a WaterSense labeled aerator, 1.5 gpm or lower 2
- If Hot water takes forever at a low-flow tap
- Then Avoid going below the 0.8 gpm at 20 psi floor in a home 3
- If Every faucet is weak
- Then Test house pressure; call a plumber
- If Debris returns after pipe work
- Then Clean often and follow utility lead guidance 5
Questions about Faucet Aerator
Do all faucets have aerators?
Nearly every modern kitchen and bathroom faucet has one, either screwed onto the spout tip or hidden inside it. Pull-down sprayer heads use their own built-in flow control instead. Utility tubs, laundry faucets and outdoor hose bibbs usually have none, and the ASME faucet standard gives those fixtures separate flow rules.
Why is my faucet suddenly low pressure?
If only one faucet is weak, a clogged aerator is the most common cause. Grit and mineral scale collect on the screen and cut the flow.
Unscrew the aerator, rinse the screens, soak off scale and test again. If every fixture in the house is weak, the problem is upstream, such as a valve or pressure regulator.
How do I clean a faucet aerator?
Unscrew it counterclockwise by hand or with a cloth-wrapped pliers, keeping the sink drain closed. Lay the parts out in order, rinse off debris and soak scaled parts in vinegar. EPA’s instruction is to unscrew the aerator and remove the debris that has collected there. Flush the faucet, reassemble and test the flow.
What gpm aerator should I buy?
For a bathroom sink, a WaterSense labeled aerator at 1.5 gpm or lower is a sound choice, and lower-flow models are sold. Kitchens are capped federally at 2.2 gpm. Avoid 0.5 gpm models at home; EPA says they generally do not give enough flow for home bathrooms.
How do I know what size aerator I have?
Check whether the threads are on the outside (male) or inside (female) of the old aerator, then match the diameter. Hidden aerators sit inside the spout and need a matching key; makers name these sizes differently. The easiest route is to take the old aerator to the store and match it in person.
Does a low-flow aerator lower water pressure?
It lowers flow, not pressure. Pressure is the push in your pipes, measured in psi. Flow is how much water comes out, measured in gpm. A low-flow aerator lets out less water at the same pressure. WaterSense requires labeled bathroom models to still give at least 0.8 gpm at 20 psi.
Can I remove the aerator to get more water?
You can, but federal rules treat the aerator as part of the faucet’s 2.2 gpm limit, and running without it removes the screen that catches grit. The stream will also splash more. If flow is too low with a clean aerator, check house pressure or fit a model with a higher allowed rating.
What is the difference between an aerated and a laminar aerator?
An aerated model pulls air into the water for a soft, white stream. A laminar model sends out clear, parallel streams with no air mixed in. Both can be made at any legal flow rate. Laminar streams splash less when filling containers, and some buildings prefer them where spray in the air is unwanted.
How much water does a WaterSense aerator save?
EPA says replacing older faucets and aerators with WaterSense labeled models can save the average family 700 gallons of water a year. That figure comes from cutting the flow from the standard 2.2 gpm to 1.5 gpm or less. It also saves energy because less heated water goes down the drain.
Should I clean my aerator after lead pipe work?
Yes. Pipe and service line work can shake loose particles that collect in the aerator screen. During the 2016 Flint response, EPA told residents to clean aerators weekly until the system recovered. Follow your utility’s flushing guidance after work on a lead service line, and ask it how to test your water.
Sources
- 10 CFR 430.32(o) and (p), Energy and water conservation standards: faucets and showerheads (Legal Information Institute copy), retrieved .
- U.S. EPA WaterSense, Bathroom Faucets, retrieved .
- U.S. EPA WaterSense, Technical Reference Manual: Bathroom Sink Faucets fact sheet (EPA-832-F-23-016, July 2023), retrieved .
- U.S. EPA WaterSense, Notice of Intent to Revise the High-Efficiency Lavatory Faucet Specification (March 2024), retrieved .
- U.S. EPA news release, EPA reminds Flint residents to take steps to reduce potential lead contamination (February 1, 2016, archived), retrieved .
Expert review
Written by the HyrePlumber Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Flow limits are quoted from 10 CFR 430.32 and EPA WaterSense documents (the faucets page, the 2023 technical fact sheet and the March 2024 Notice of Intent).
Cleaning guidance is EPA’s 2016 Flint release; No fixed cleaning interval is given because no federal source sets one. The bucket-test table is arithmetic on EPA’s 0.25-gallon-in-10-seconds check. No prices are given.
Suggest a correction. We fix errors and say what changed.