Faucet aerators: standard M24x1 / M22x1
How to clean or replace a faucet aerator
When a kitchen or bathroom faucet sputters, sprays sideways or runs weak on both hot and cold, the aerator at the tip of the spout is usually clogged with grit or scale. Cleaning it takes ten minutes. Replacing it means matching the thread size, and some Moen and Delta faucets hide the aerator inside the spout.
- Standard sizesM24x1 male, M22x1 female
- US threads15/16"-27 male, 55/64"-27 female
- Federal max flow2.2 gpm at 60 psi
- WaterSense bath1.5 gpm or less
Which kind of aerator do you have?
- Exposed, female
- The aerator is a ring screwed over the outside of the spout tip. Threads are inside the aerator.
- Exposed, male
- The aerator screws up into the spout. Threads are on the outside of the aerator shell.
- Hidden (cache)
- You see only a small screen or flat face flush with the spout and nothing to grip. Moen says a concealed aerator will need a tool: for round ones with indentations the tool is supplied with the faucet or a service kit; oval styles take a 1/8, 5/64 or 7/64 inch hex wrench, or needle-nose pliers for a press-fit version. Delta's RP52217 wrench removes cache aerators on its Innovations, Leland, Lahara, Addison, Dryden, Linden and Classic bathroom faucets.
- Tamper-proof
- Some housings are made to need a special key. If yours has slots or notches and will not turn by hand, it may be one of these.
Clean first, replace if damaged
Most aerators only need cleaning. Replace one if the housing is cracked or bent out of round, the threads are damaged, or the screen is torn. EPA's lead guidance also recommends cleaning the faucet screen regularly, since particles collect there.
If the flow is weak on only hot or only cold, the aerator is not the cause: both sides pass through it. Look at the faucet cartridge instead, such as the Moen 1225.
| Item | Part | Number |
|---|---|---|
| 1 | Spout tip | faucet |
| 2 | Housing, threaded male or female | match thread size |
| 3 | Insert with screens | match insert size |
| 4 | Rubber washer (often sticks inside the spout) | comes with a new aerator |
Hidden aerators: Moen tool supplied with the faucet or a service kit; Delta wrench RP52217 for listed collections.
Tools and supplies
- Cloth or masking tape to protect the finish
- Slip-joint or channel-lock pliers if it is stuck
- White vinegar and a small bowl
- Old toothbrush
- Hex key or aerator tool for hidden aerators
Aerator thread sizes
An aerator with a housing has three parts: the housing, the insert and the washer. The housing screws onto the spout with either a male thread (threads on the outside of the aerator shell) or a female thread (threads inside it). These are the housing sizes Neoperl, a major aerator maker, lists for each insert size:
| Insert size | Female housing | Male housing |
|---|---|---|
| Standard / Regular | M22x1, 55/64"-27 | M24x1, 15/16"-27 |
| Junior | 3/4"-27 | 13/16"-27 |
| Tiny Junior | M19x1 | M20x1 |
| Tom Thumb | M16x1, 3/8" | M18x1 |
A female aerator screws onto a spout with threads on the outside; a male aerator screws into a spout with threads on the inside. The easiest match is to take the old housing to the store.
Flow rate
Federal rules (10 CFR 430.32) cap kitchen and bathroom faucets, and their replacement aerators, at 2.2 gallons per minute at 60 psi. EPA's WaterSense label for bathroom sink faucets and accessories requires 1.5 gallons per minute or less. A 1.5 gpm aerator on a bathroom sink saves water without changing anything else.
Remove, clean and refit the aerator
Close the faucet and plug the drain
Turn the faucet fully off and put the stopper in the drain so small parts cannot fall in. Delta says you do not need to shut off the water supply to clean an aerator. If the faucet itself drips, close the stop valves under the sink first, turning each clockwise until snug.
Safety: If a stop valve under the sink will not turn or leaks when you move it, leave it alone and work with the faucet closed.
Unscrew the aerator by hand
Grip the aerator and turn it counterclockwise, the direction Delta gives. Do not squeeze hard: Delta warns it can bend into an egg shape. If it will not turn, wrap a cloth around it and use pliers gently. If it is still stuck, wrap a rag soaked in white vinegar around it for a few hours to soften the scale.
Note the order of the parts
Lay the housing, screens and washer out in the order they came apart. The washer sometimes stays stuck inside the spout; pick it out.
Soak and scrub
Soak the parts in white vinegar (Delta suggests overnight for heavy scale), then scrub with a toothbrush and rinse. Run the faucet briefly without the aerator to flush grit out of the spout, with your hand cupped over the stream.
Reassemble and refit hand-tight
Put the parts back in the same order with the washer on top, and screw the aerator back on hand-tight. Run the water and check for drips around the threads.
Replacing it instead
Take the old aerator to the store to match male or female thread and size, or match it against the size table above. Choose a flow rate: 1.5 gpm or less for a bathroom sink meets WaterSense; kitchen faucets are limited to 2.2 gpm.
Stop and call a plumber if
- Water leaks from the base of the faucet or the stop valves and supply lines under the sink.
- The spout threads are stripped or cracked, so no aerator will hold. That is a faucet replacement.
- Supply lines under the sink are corroded, kinked or bulging.
- Flow stays weak with the aerator off. The restriction is in the faucet cartridge or the supply, not the aerator.
Troubleshooting by symptom
| What you see | Likely cause and fix |
|---|---|
| Water sprays sideways or sputters | Grit in the screen or a misaligned insert. Clean and reassemble in order. |
| Weak flow on both hot and cold | Clogged aerator. Clean it; if flow is still weak with the aerator off, check the cartridge and stops. |
| Weak flow on one side only | Not the aerator. Check that stop valve is fully open, then the cartridge. |
| Drip from around the aerator threads | Washer missing or out of place, or the housing cross-threaded. Refit with the washer seated. |
| Aerator will not budge | Scale. Vinegar-soaked rag for a few hours, then cloth and pliers. Hidden aerators need their tool. |
Official parts and warranty
A cracked or defective aerator may be covered by the faucet warranty: Moen and Delta both replace defective parts for the original purchaser.