The coffee machine gets clogged with limescale because the water used contains dissolved minerals, mainly calcium and magnesium. When heated, these minerals precipitate in the form of solid limescale that deposits on the walls and heating elements, creating an accumulation called scale.
Limestone simply comes from the minerals naturally present in the soil, mainly composed of calcium carbonate and sometimes magnesium carbonate. When rainwater passes through the soil, it picks up these minerals along the way, which explains why your tap water, depending on the region you live in, can be more or less "hard," meaning rich in limestone. The more dissolved minerals the water contains, the "harder" it is considered. Even though it is completely natural and harmless to your health, the calcium carbonate dissolved in the water reacts easily when the water is heated. And that's when the trouble starts for your coffee machine...
When water heats up in a coffee machine, the dissolved lime scale turns into small solid crystals. It's like when you boil a pot of water several times: you end up with a white deposit at the bottom. This deposit is the famous scale. It forms especially when the water reaches a certain temperature, generally around 60°C and above. The more the water heats up and evaporates, the more these crystals accumulate, become sticky, and eventually form a hard layer on all internal surfaces. Gradually, this layer thickens, attaching itself to pipes, metal parts, seals, and even heating elements like the electric resistance. The harder the water, in other words the more it contains calcium and magnesium ions, the faster the lime scale accumulates.
The water tank is often the first to suffer from limescale. The water stagnates slightly, gradually encouraging deposits. The heating element, which raises the water temperature, is particularly exposed: by heating, it promotes the rapid crystallization of limescale on its surface. The result: it heats less efficiently and more slowly, with an obvious loss of effectiveness. The small pipes inside the machine are not spared either: their reduced diameter makes any buildup of scale problematic, slowing down or even partially blocking the water flow. Finally, the water pump, essential for pushing hot water into the coffee, also suffers from the attacks of scale: the harder it works, the more it risks premature wear.
The buildup of limescale in a coffee machine gradually causes blockages in the pipes, water hoses, and even the small internal nozzles. Because of this, the water flow slows down, the pump works harder, and it becomes more difficult for the machine to heat the water efficiently. As a result, the coffee flows more slowly, the temperature is less stable, and the final taste of the coffee can even suffer. Another problem: limescale forces the machine to consume more energy to compensate for the loss of performance. In the long term, all these extra efforts lead to premature wear of the components, which can seriously reduce the lifespan of the device. In extreme cases, excessive limescale buildup can even cause a complete breakdown requiring costly repairs.
To prevent limescale from becoming too invasive, the simplest method is to use filtered or low-mineral water. This greatly limits deposits that clog your coffee maker. An easy preventive step to adopt is to regularly empty the reservoir and wipe the wet parts, which prevents limescale marks from settling too quickly. If, despite everything, limescale builds up, a good regular descaling remains essential: use either a specific product or a homemade solution with diluted white vinegar, which effectively dissolves limescale. Remember to rinse well after descaling to avoid an unpleasant taste in your next coffee. Some modern machines even offer automatic descaling programs to make maintenance easier.
A tartar layer of only 1 mm increases the energy consumption of heating devices by up to 10%, which means that your limescaled coffee machine uses more electricity, thereby raising your energy bill.
White vinegar, often considered an economical natural solution for descaling, can damage certain internal components (seals and pipes) of modern coffee machines. It is better to use descaling products recommended by the manufacturers to sustainably preserve your equipment.
Depending on where you live, water hardness can vary greatly. So-called 'hard' water (rich in calcium and magnesium) causes more limescale deposits than soft water. You can easily find out the hardness of your water by consulting your supplier's website or using test strips available in stores.
Contrary to popular belief, bottled mineral water, often considered a healthy option, is generally rich in minerals and therefore more likely to cause limescale buildup in your coffee machine faster than filtered water or low-mineral spring water.
Occasionally drinking coffee from a slightly limescaled machine is generally not harmful to health. However, significant limescale buildup alters the taste of the coffee, reduces heating efficiency, and can promote bacterial growth. It is therefore recommended to descale your machine regularly to maintain good coffee quality and ensure perfect hygiene.
The recommended descaling frequency varies depending on the type of machine, usage frequency, and the hardness of your water. On average, descaling every 2 to 3 months is advised. However, the presence of very hard water may require more frequent procedures.
The limestone content in the water mainly depends on your geographical region. You can find out this parameter by consulting the information provided by your town hall or your water supplier. At home, you can also observe visible signs such as white deposits around faucets or in your kettle, which generally indicate water rich in limestone.
White vinegar is indeed a cost-effective alternative to commercial descalers, as it effectively dissolves limescale. However, some manufacturers advise against its use because it can be harsh on seals or certain internal components sensitive to vinegar. It is therefore recommended to always consult your machine's user manual before using white vinegar for descaling.
If no descaling is performed over a long period, the buildup of limescale will significantly reduce the water heating efficiency, increase electricity consumption, cause water leaks, and may lead to irreversible damage to certain internal components (heating elements, pumps, pipes). This significantly shortens the lifespan of your coffee machine.
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