Which tap aerator do I need? UK sizes explained

Tap aerators are one of those parts that seem simple until you try to buy one. Male or female? M22 or M24? Screw-in or push-fit? Get it wrong and the new one rattles around in a drawer for ever. The good news is that UK taps stick to a small handful of standards, so once you know what you are looking at, picking the right aerator takes about a minute.

The three types of aerator fitting

There are only three fittings you are likely to meet on a UK tap.

• Male thread, usually M24. The threads are on the outside of the aerator itself, and they screw up into a spout where the thread is hidden inside. This is the most common kitchen mixer setup.
• Female thread, usually M22. The threads are on the inside of the aerator, and it screws onto a spout that has visible threads on the outside.
• No thread at all. Some spouts are smooth with nothing to screw into. For these, a push-fit aerator grips the outside of the spout with a rubber sleeve instead. It is also the easy option when you simply do not want to deal with threads.

Bathroom basin taps sometimes use smaller threads such as M18 or M16, and a few larger kitchen taps use M28, but M22 and M24 cover the vast majority of UK kitchens.

How to tell which one you have

Look at the end of your tap spout.

1. Threads visible on the outside of the spout? You need a female aerator. Measure straight across the threads with a ruler. About 22mm means the standard M22.
2. No threads visible, but a thread inside the spout? You need a male aerator. Measure across the opening. About 24mm means the standard M24.
3. Completely smooth spout? Nothing will screw in, so a push-fit aerator is the answer. Measure the outside diameter of the spout end and check it against the range the push-fit model accepts.

If your old aerator unscrews, the easiest check of all is to take it with you or measure it directly. Aerators have a normal right-hand thread, so looking down at the tap from above, turn it anticlockwise to loosen. Use a cloth to protect the finish if it is stiff, and if limescale has cemented it in place, a cup of vinegar held around the end of the spout for an hour usually breaks the grip.

When a push-fit aerator is the better choice

Screw-in aerators are neat, but the push-fit style has two real advantages.

First, there is nothing to unscrew and no thread to match, so the sizing question mostly disappears. A model like our kitchen tap aerator with a 360 degree swivel slips over the end of most round kitchen spouts and grips with a soft rubber sleeve. One caution from our own product notes: if your spout is square or unusually wide, measure it before buying.

Second, you can add features a plain insert cannot give you. A swivel head lets you point the stream into every corner of the sink, which makes rinsing the basin far quicker. If you want a spray option and a pull-down reach as well, a 3 in 1 tap extender does the same job with a flexible neck.

Does a new aerator actually change anything?

Yes, and it is usually the cheapest fix in the whole kitchen. A good aerator mixes air into the water, which softens the stream so it stops splashing off plates, and it reduces the amount of water you draw without making the tap feel weaker. If your tap currently sputters or sprays sideways, the old aerator is probably clogged with scale, and a replacement transforms it.

We have covered both of those problems in more depth already: see how to make a weak kitchen tap feel stronger for the diagnosis steps, and water saving upgrades that actually work for the honest numbers on what an aerated flow saves.

The one minute summary

• Threads outside the spout: female aerator, almost always M22.
• Threads inside the spout: male aerator, almost always M24.
• Smooth spout, or you just want the simple route: push-fit, and check your spout is round and a normal width.
• Old aerator stuck: cloth for grip, vinegar for limescale, anticlockwise from above.

Still not sure from looking? Send us a photo of the end of your tap at hello@loftenhome.com and we will tell you straight whether ours will fit, including telling you honestly if it will not.