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Tap Aerators & Diffusers

Replacement tap aerators, tap diffusers and aerator inserts for kitchen taps, basin taps and bath taps, including male and female thread types from M16 to M24. We stock flow limiters, cache aerators, ball joint and swivel aerators, flow straighteners, and rectangle and odd-shape aerators. Thread sizes and fitting types not widely available through standard trade counter ranges.

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Tap Aerators & Diffusers

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Neoperl Home Install Kit HIKIT

Neoperl Tap Aerator Assortment Box ARBOX

Tap Aerator Replacement for Kitchen, Bath and Basin Taps

Replacement aerators, diffusers, inserts and nozzles for mixer taps, monobloc taps and bath spouts.

A tap aerator that's blocked with limescale, cracked, or simply worn out will reduce flow to a trickle, cause splashing, or produce an uneven spray pattern. In most cases, a tap aerator replacement costs a fraction of a new tap and takes minutes to fit. We stock aerator inserts, tap diffusers, flow limiters and housing assemblies for kitchen tap aerators, basin tap aerators and bath tap aerators, covering male and female thread types from M16 to M24. If your tap produces a flat, irregular stream or the flow has dropped noticeably, the aerator or diffuser is usually the first part to check. Cache aerators, swivel aerators, flow straighteners and TT and TJ inserts are also stocked for tap types where a standard screw-in insert doesn't fit. For unusual shapes or older models, our Rectangle and Odd Shape Aerators section covers non-standard spout ends. We stock thread sizes and fitting types that most plumbing suppliers don't carry as standard.

Which Tap Aerator Do You Need?

The same small part goes by many different names. Find yours below, then use the size guide to confirm the thread.

What it's called	What it is and when you need it
Tap aerator	The standard screw-in fitting at the end of a tap spout that mixes air into the water stream. Comes in male thread (screws onto the outside of the spout) or female thread (screws into the inside). Most common replacement part in this category.
Tap diffuser / tap diffuser insert	A soft rubber or plastic insert that sits inside the aerator housing and shapes the flow pattern. A diffuser nozzle that has split, collapsed or become misshapen causes splashing or a fan-shaped stream instead of a smooth column.
Aerator insert / tap aerator insert	The inner cartridge of a two-part aerator assembly. The housing stays in place; only the insert is replaced. Common on kitchen taps where the outer housing is fixed or recessed. Plastic tap aerator inserts are the most widely fitted type.
Tap nozzle / tap nozzle replacement	A broader term customers use for the complete end-of-spout assembly including the housing and any insert. If the whole nozzle has cracked or the thread is damaged, a full tap nozzle replacement is needed rather than just a new insert.
Tap strainer / tap gauze / tap mesh	The fine mesh screen inside the aerator that filters debris from the water supply. A blocked tap strainer reduces flow without any visible damage to the housing. Can sometimes be cleaned, but replacement is more reliable on older fittings.
Cache aerator	A recessed aerator fitted flush inside the tap spout so it's not visible from outside. Requires an aerator key to remove and replace. Common on higher-end kitchen and bathroom taps. Cache aerators have a specific key size, so confirm the diameter before ordering.
Swivel aerator / ball joint aerator	An aerator fitted with a ball-and-socket joint that allows the spout end to be angled. Used on kitchen taps where directional control of the flow is needed. The swivel mechanism can wear or seize, making the joint stiff or causing drips at the joint.
Flow straightener	A fitting that removes turbulence from the water stream without adding air. Used where aeration is not wanted, such as filling vessels cleanly or where low water pressure makes a standard aerator reduce flow too much.
Flow limiter	A restrictor insert that caps the flow rate regardless of supply pressure. Fitted inside the aerator housing. Useful for water-saving purposes or where supply pressure is high enough to cause splashing even with a standard aerator fitted.
Perlator	The trade name used by Neoperl for their aerator range, widely adopted as a generic term in the UK plumbing trade. If your tap documentation refers to a perlator, you need a standard tap aerator in the correct thread size and type.
Faucet aerator	The US English term for a tap aerator. Identical part, different name. If you've been searching for a faucet aerator replacement or faucet diffuser, the aerators and inserts in this category are what you need.
TT and TJ inserts	Proprietary insert formats used in specific tap types, typically where the spout end has a non-standard internal profile. TT and TJ refer to the insert shape rather than a thread size. Check your tap's documentation or send us a photo if you're unsure.
M22/M24 housing inserts	Reducer inserts that allow a smaller aerator to be fitted inside a larger M22 or M24 housing. Used when upgrading or replacing an aerator where the original size is no longer available, or when fitting a water-saving insert into a standard housing.
Rectangle / odd-shape aerator	Aerators made for spout ends that are not round. Found on contemporary square-profile or blade-style taps where a standard circular aerator cannot be fitted. If your tap spout is rectangular or an irregular shape, check the Rectangle and Odd Shape Aerators section.
Tap sprinkler / tap spreader	Informal names customers use for an aerator that produces a wide, spread pattern rather than a focused column. Usually indicates a worn or damaged diffuser insert rather than a separate product type. Replacing the insert resolves the spray pattern.

Tap Aerator Size Guide: Finding the Right Thread

Not sure of your thread size? Use the diagram and measurements below to confirm whether you have a male or female fitting and which M-size you need.

Tap aerator sizes in the UK are given as M-sizes (metric thread diameters). The two measurements you need are: Measurement A (the outer diameter of the thread) and Measurement B (the inner diameter). Male thread aerators screw onto the outside of the spout; female thread aerators screw into the inside. Measure your existing aerator or the spout end with digital callipers for the most accurate match.

Tap aerator thread size guide showing male and female M-size measurements from M16 to M24 with Measurement A and Measurement B columns

If you've measured your aerator and still aren't certain of the size, email us a photo of the spout end alongside a coin or ruler for scale and we'll identify it for you.

Questions About Tap Aerators and Diffusers

Common questions about fitting, sizing and replacing tap aerators.

What is a tap aerator and what does it do?

A tap aerator is a small fitting screwed onto or into the end of a tap spout that mixes air into the water as it flows out. This reduces the actual volume of water used, softens the feel of the flow, and prevents splashing in the basin or sink. Most UK kitchen and bathroom taps have an aerator fitted as standard, either as a visible screw-on type or as a recessed cache aerator set flush inside the spout. When an aerator fails, the most common signs are a sudden drop in flow rate, an uneven or spitting stream, or visible limescale blocking the mesh screen.

How do I measure my tap aerator to find the right replacement?

You need two measurements and a thread type. First, establish whether your aerator is male thread (the thread is on the outside of the spout, and the aerator screws onto it) or female thread (the thread is inside the spout, and the aerator screws in). Then measure the thread diameter with digital callipers: the outer diameter gives you Measurement A and the inner diameter gives you Measurement B. UK tap aerator sizes run from M16 to M24. The size guide image above shows the full measurement reference for both thread types. If you don't have callipers, remove the old aerator and email us a photo with a coin or ruler for scale.

Do tap aerators fit all tap types, including mixer taps, basin taps and bath taps?

Aerators fit most tap types but the thread size, thread type and fitting format vary significantly between them. Kitchen mixer tap aerators are typically M22 or M24 male thread. Basin tap aerators are more often M18 or M20 female thread. Bath tap aerators vary by manufacturer and spout design. Shower head fittings use a different thread standard to standard tap aerators, so a shower aerator insert is a separate product. For mixer tap aerator replacements, the swivel aerator option is worth considering if the original had directional adjustment. Check the sub-categories on this page or use the size guide above to narrow down your specific fitting.

What is a universal tap aerator and will it fit my tap?

A universal tap aerator typically comes with multiple adaptor washers and housings to cover the most common thread sizes, usually M18 to M24 in both male and female thread configurations. They work well for standard round spout ends in the most common sizes, but they are not truly universal. Cache aerators, TT and TJ inserts, rectangular aerators, swivel types and non-standard thread sizes all require specific fittings. If your tap takes a non-standard aerator, a universal kit is unlikely to fit correctly. The Adaptors, Washers and Housings sub-category covers the individual components needed to adapt or extend a housing for an unusual fitting configuration.

I can't identify my aerator from the size guide. What should I do?

If the size table doesn't give you a confident match, the quickest route is to email a photo to sales@bathroomspareparts.co.uk. Photograph the spout end straight-on and from the side, with a coin or ruler in frame for scale. Our team identifies aerator types from photos daily and can confirm the thread size, type and which sub-category to order from. For taps where the make and model is known, include that in your email. For older or discontinued tap ranges where the aerator size is no longer listed, our Unknown Size section stocks items specifically for this situation.

Not sure which aerator fits your tap?

Send us a photo of your tap spout and the existing aerator. We'll identify the thread size, type and correct replacement, usually within one working day.

Email Us a Photo