How to Clean Limescale from a Faucet Aerator Without Removing It

When a faucet’s stream is weak or sprays to the side, the most common cause is the small mesh filter fitted at the faucet spout, called an aerator, or "flow breaker," that is partially clogged with limescale or sand carried by the water. In most cases, all you need to do is leave it to soak in a mild acidic solution while it remains attached to the faucet, and remove it only if the stream is still weak after soaking.

• A weak stream or one that sprays to the side almost always indicates a partially blocked mesh, not a problem with the upstream plumbing.
• You can recognize limescale because it forms a hard, whitish or grayish crust that does not come off with rinsing; loose sand and debris, on the other hand, wash away on their own with a stronger stream of water.
• It is best to start with the method that does not require removal and only take the aerator out completely if cleaning it in place is not enough.
• If an additional ceramic and activated carbon filter is installed, it should be replaced when due: it is not designed to be cleaned like the aerator.

Weak stream or spraying to the side: limescale or sand?

Before choosing a method, it is worth figuring out what is actually blocking the mesh. Limescale forms when hard water, rich in calcium and magnesium, loses dissolved carbon dioxide because of heat or a drop in pressure: calcium carbonate then precipitates and settles as a solid crust, whose color ranges from white-gray to pink or reddish-brown when iron compounds are also present (source: Limescale, Wikipedia). Hard water itself is defined by its calcium and magnesium content, and the deposits it leaves on faucets and pipes consist mainly of calcium carbonate, magnesium hydroxide, and calcium sulfate, which are solid enough to restrict the flow of water over time (source: Hard water, Wikipedia).

Sand or sediment grains carried by the water supply, by contrast, do not bind to the aerator mesh: they tend to collect in the finer openings, but a vigorous rinse, perhaps with a toothbrush, often removes them without any need to soak the aerator. If the mesh remains blocked after rinsing and you can see a hard film that resists a light scratch with your fingernail, it is almost certainly limescale, and that is when an acidic soak makes a difference.

The simplest method: clean the aerator without removing it

One of the most practical ways to tackle a scaled-up aerator without taking it off the faucet, which is also useful when it does not unscrew easily by hand, is to fill a small plastic bag with white vinegar or a diluted citric acid solution, secure it tightly around the faucet spout with a rubber band or cable tie so the aerator is completely submerged, and leave it to work (source: Bob Vila, how to clean an aerator). After soaking, gently brushing it with an old toothbrush helps remove any remaining crust; if the deposit is thick, repeating the soak for a few hours or overnight works better than trying to force it off, which could damage the mesh.

Both vinegar and citric acid should be diluted, not used undiluted. A 6% citric acid solution effectively removes scale from glass without scrubbing, but in concentrated form it irritates the skin and eyes and is classified as corrosive to metals (source: Citric acid, Wikipedia). Vinegar likewise dissolves mineral deposits well, but it can corrode aluminum, copper, and some lower-quality stainless steel alloys, as well as damage rubber seals if left in contact for too long (source: Vinegar, Wikipedia). That is why it is best to dilute the solution with water and not leave it to work for days: a soak of a few hours, repeated if necessary, is safer for the faucet’s chrome finish than a prolonged soak with undiluted product.

When it is worth removing the aerator

If the stream is still weak after one or two soaks, the next step is to remove the aerator and clean its components separately. Unscrew the aerator by hand or, if it is too tight, use pliers; in that case, it is best to wrap the aerator itself in a piece of adhesive tape before gripping it with the pliers, so the metal teeth do not scratch the faucet’s chrome or brushed finish. Once it is removed, separate the mesh discs and soak them in vinegar for twenty or thirty minutes to dissolve the more stubborn residue before brushing them, rinsing them, and reassembling everything (source: Bob Vila, how to clean an aerator).

It is also worth checking the condition of the internal parts while the aerator is removed. If the flow restrictor disc or mesh is deformed or broken, rather than simply covered in scale, cleaning it will not restore a steady stream: in that case, replacing the aerator is the most reliable solution, because soaking a damaged component, no matter how long, will not restore its function (source: Bob Vila, how to clean an aerator).

If the aerator is stuck or recessed

Some faucets, particularly those with a pull-out spout or an aerator recessed into the mixer body, have an aerator that does not unscrew by hand and may seem to be stuck because of the very limescale you want to remove. For that specific case, with the right tools and precautions to avoid damaging the threads, it is best to follow the dedicated guide on how to remove a recessed or stuck aerator, which covers removal in the most difficult cases.

How often to repeat the cleaning

There is no interval that works for every home, because how quickly limescale forms again depends on the hardness of the local water: the harder the water, the faster the crust reforms after cleaning. The most reliable guide is to watch the stream rather than follow a fixed schedule: as soon as you notice that the water is flowing more weakly or starting to spray to the side, it is time to repeat the soak, before the blockage becomes complete. In an area where the water is known to be hard, checking a little more frequently helps you avoid a complete blockage that requires removal.

Aerator and additional ceramic and activated carbon filter: two different types of maintenance

If you have installed an additional faucet filter, such as the Hydrion ceramic and activated carbon filter, you should treat the two types of maintenance separately. The aerator is cleaned as described above because its only job is to break up the stream into small air bubbles and trap coarse particles; the filter cartridge, on the other hand, is a consumable that should not be removed and scrubbed, but replaced when the flow decreases. The product page states that the cartridge lasts about six months, depending on water quality and how much water is filtered, and recommends checking the flow regularly and replacing the cartridge when needed, not trying to clean it.

It is also worth being clear about what this type of filtration does and does not do. According to the product page, the ceramic layer traps particles and the activated carbon helps improve the taste and smell of tap water associated with chlorine; neither reduces the water’s hardness or its dissolved salt content, so having the filter does not remove the need to clean limescale from the aerator using the method described above. For a closer look at what a carbon or ceramic filter can and cannot do about limescale, the guide to faucet limescale filters explains this distinction in detail, while anyone who wants to better understand what the dissolved salt content in water measures can consult the explanation of TDS in water already published on the blog.