Descaling and cleaning a washing machine: the difference

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Descaling and cleaning are two different jobs

Almost every guide to cleaning a washing machine lumps together two problems that have nothing to do with each other. That is not a detail, because the product that solves one does nothing at all against the other.

The first problem is limescale. The Consumentenbond sums it up briefly in its maintenance advice for washing machines: limescale forms when heat, water and lime particles come together, and in a washing machine that is the heating element. A scaled-up element takes longer to heat and a wash costs more energy. You see nothing of it, because the element sits under the drum. You only notice it in your energy bill or, in the worst case, in an element that gives out.

The second problem is biofilm: a grey-brown, soapy layer of grease, detergent residue and fabric softener in which bacteria feel right at home. That layer sits in places you can see, such as the edge of the rubber door seal and the detergent drawer. The Consumentenbond puts the cause down to dosage: too much detergent causes biofilm, too little does not get the laundry properly clean. The problem gets worse the colder you wash, and in recent years nearly everyone washes colder.

The two therefore call for opposite approaches. Against limescale you use an acid and a high temperature, and it is precisely that high temperature that causes limescale. Against biofilm you use a high temperature and as little extra product as possible. Anyone who attacks a smelly machine with a descaler solves nothing. Anyone who wants to cut energy use with a boil wash makes their element dirty slightly faster. The same sequence plays out in the rest of the house, and our overview of how limescale forms and what keeps it away works it out for the bathroom and kitchen.

There is one more practical difference. Limescale is a slow problem that you tackle every six months. Biofilm is a maintenance problem that you tackle weekly or monthly. A machine that is well maintained almost never needs a descaling session, whereas a machine that is only ever descaled will still start to smell.

How often it is really needed with Dutch water

This is where the advice differs most, and that is because almost every piece of advice is written for water that is harder than the water that comes out of the tap here.

The manufacturer side is clear. Siemens writes in its maintenance instructions that you should descale a washing machine every 3 to 6 months with a descaler intended for washing machines. That is a safe lower limit that has to hold worldwide, including in areas where the water is twice as hard as it is here.

The Dutch side is just as clear, but pointing the other way. The Consumentenbond says limescale forms in places with hard tap water and adds that the water in many places in the Netherlands is not very hard. Vitens puts it even more firmly: truly hard water has almost disappeared in the Netherlands, because water companies soften the water where needed. Milieu Centraal says it is soft to medium.

The number that matters is on your detergent pack. The Consumentenbond describes three dosage groups: low up to 8.4 degrees German hardness, medium up to 14 degrees German hardness, and high above that. Most of the Netherlands falls into the lowest or the middle group. That is exactly why the monthly descaling session you read about everywhere is rarely needed here, and why the differences per municipality make so much difference to what you need to do.

The practical translation, with the caveat that your own hardness is what counts:

• Do you fall in the low group, up to 8.4 degrees German hardness, and do you mostly wash at 30 and 40 degrees with liquid detergent? Then descaling 1 to 2 times a year is plenty.
• Do you fall in the middle group, up to 14 degrees German hardness? Then you are at 2 to 3 times a year, so the upper end of the 3 to 6 month advice.
• Are you above that, or do you wash a lot at 60 degrees and higher with powder? Then every 3 months is sensible, because powder and heat both contribute to the deposits.

The Consumentenbond sets a clear limit: use descalers at most once a month, follow the dosage advice for soft water and only add it when you wash at 60 degrees or higher. That last point is almost always forgotten. A descaler in a 30 degree programme does hardly anything, because both the limescale deposit and its dissolving are a matter of temperature.

Which product works, and which does not

Limescale dissolves in acid. That is all the chemistry there is, and it explains why vinegar, citric acid and a dedicated descaler all work. The question is not whether they dissolve limescale, but what else they affect along the way. A washing machine has rubber seals, a door seal, a pump and an aluminium or stainless steel element, and that is where the difference lies.

A descaler for washing machines

This is what every manufacturer prescribes. Siemens explicitly names a descaler for washing machines, and Bosch carries its own line for it. Such a product is based on citric acid or a similar organic acid and contains substances that protect the metal. You pay a few euros per session, and at 2 to 4 sessions a year you are talking about the kind of amount that pales next to the price of a new heating element.

Citric acid

Citric acid is the active ingredient in most ready-made descalers and thereby the safest home remedy. You buy it as a powder at the drugstore. The big advantage over vinegar is the smell: vinegar smell soaks into rubber and plastic and then comes back in your laundry for weeks, citric acid does not. The drawback is that you determine the dosage. Stick to the dosage advice on the packaging and do not make it stronger in the hope that it goes faster; overly concentrated citric acid can actually precipitate.

Cleaning vinegar and table vinegar

This is the biggest disagreement on this subject, and it is more honest to say so than to pretend there is a single answer. The Consumentenbond lists cleaning vinegar, soda and a dishwasher tablet as a possibility for descaling a washing machine, and in the same breath adds that washing machine manufacturers recommend special descalers because, in their view, vinegar, soda or a dishwasher tablet damage washing machine parts, such as the rubber seals. Vitens recommends cleaning appliances regularly with, for example, cleaning vinegar, but adds that you should always read the appliance’s cleaning instructions first.

In practice it comes down to this. Vinegar works, and it is cheap. The risk is not in a single session but in the repetition: every time the rubber seals come into contact with acetic acid, some of their suppleness is lost, and a leaking door seal is an expensive repair. On every bottle the percentage of acetic acid is stated and that is the only number that counts. Table vinegar from the supermarket is generally around 4 to 5 percent, cleaning vinegar around 8 percent. Stronger means faster, not better. Anyone who uses vinegar anyway therefore picks the weaker variant, keeps it to a few times a year at most and never leaves it for hours in a standing drum.

Soda and the dishwasher tablet

Soda is not an acid but a base and so does not dissolve limescale. Soda is good at loosening grease, and that is where its popularity comes from: people throw soda into the machine against the smell, it works against the smell, and they conclude that the machine has been descaled. It has not. The same largely applies to the dishwasher tablet, which mainly contains bleach and grease solvents. Both are cleaners, not descalers, and both are on the list that manufacturers warn about.

What you can skip

Cola, chlorine and penetrating oil all come by as tips and do nothing useful against limescale in a washing machine. Chlorine only bleaches the colour of the deposit away. Milieu Centraal is brief about it in its general cleaning tips: using more cleaning product does not make things cleaner.

Descaling your washing machine, step by step

The action itself takes five minutes; the machine then does the work for an hour or two. All you need is the product and an empty machine.

1. Empty the drum completely. A descaling session with laundry inside is a waste of your clothes and of the product: the acid attaches to the textile instead of to the element. Also feel in the fold of the door seal, because socks get stuck there.
2. Put the product in the drawer for the main wash. Not in the pre-wash compartment and not in the drum, because then it is flushed straight out again at the start of the programme.
3. Choose a programme of 60 degrees or higher, without pre-wash. This is the step that makes the difference. Below 60 degrees the acid does not work properly and the limescale stays. A cotton programme at 60 degrees is fine; an eco programme takes a long time but keeps the temperature low.
4. Let the programme run all the way through. Do not interrupt halfway. The last part of the cycle is the rinse in which the dissolved limescale leaves the machine.
5. Then run a short empty programme without product. This rinses away residues that would otherwise end up in the next wash. It takes a quarter of an hour and prevents stains and a sharp smell in your first wash.
6. Pull out the detergent drawer and rinse it. After a descaling session the dirt in the drawer comes loose most easily, so this is the right moment.

Cleaning: door seal, drawer, filter and a real 60 degrees

This is the job that is needed far more often than descaling, and that almost nobody needs to solve with a product. The Consumentenbond’s recipe is almost boring: run a wash at 60 degrees at least once or twice a month, because that limits bacterial growth.

With an important footnote, which is almost never mentioned: do not choose the 60 degree eco programme or the newer eco 40-60 programme for this, because according to the Consumentenbond they do not wash long enough at high temperature. Many people therefore think they wash hot every month while their machine never brings the water above 45 degrees. If you also wash with liquid detergent and often use fabric softener, the Consumentenbond says it can be a good idea to occasionally run a boil wash at 90 or 95 degrees as well.

Why that temperature matters, Vitens explains in a sentence that is about hot water appliances but applies equally well here: the temperature must be at least 55 degrees to kill harmful bacteria. Lower water is more economical, but more bacteria-friendly. The RIVM works out that same logic for water pipe installations and legionella: standing water and lukewarm temperatures are the combination you want to avoid.

The three places you do by hand:

• The door seal. The rubber around the drum opening is, according to the Consumentenbond, the place where dirt accumulates. Pull the fold open, wipe it inside and out, and do the door edge and the hinge at the same time. Once a month is enough; for a machine that already smells, more often in the first weeks.
• The detergent drawer. Most drawers come all the way out with a button. Soak in warm water, brush it off, and also check the opening the drawer slides into, because that is where the deposit you do not see hangs.
• The lint or drain filter. It sits behind the little flap at the bottom right. Put a flat tray and a towel underneath, because more water always comes out than you think. Two to four times a year is customary.

And the easiest of all: leave the door and the detergent drawer ajar after every wash. A drum that can dry does not start to smell. That costs nothing and makes more difference than any bottle of machine cleaner.

The products side by side

Calgon and other anti-limescale products: needed or not

Few products are as firmly established as the weekly anti-limescale product, and few products get such a short verdict from the Consumentenbond. According to them, anti-limescale products such as Calgon are not needed if you follow the maintenance tips, or if you do not have hard water. They add a cost argument: the cost of using an anti-limescale product weekly adds up considerably.

The reason behind it is more substantive than the price tag. Detergent already contains ingredients against limescale, says the Consumentenbond, and that is why the dosage advice differs per water hardness. An anti-limescale product therefore largely does what your detergent already does, and you pay for it a second time. With truly hard water, in the highest dosage group, the story is different and it can make sense. But the highest group only starts above 14 degrees German hardness, and Dutch tap water is rarely there.

Work it out for your own situation. With four washes a week and one dose per wash you reach more than 200 doses a year. That is a fixed amount per year to prevent a problem that you largely do not have with soft to medium water, whereas 2 descaling sessions a year tackle the same limescale for a fraction of that amount. Anyone who would rather spend that money on the cause is better off first reading what soft water costs and delivers over its whole lifetime, because that too is a calculation and not a given.

Your detergent dosage is probably wrong

This is the finding that appears in almost no article on this subject, even though it is the cheapest improvement of all. On every pack of detergent there is not one dosage but a table of dosages per water hardness. The Consumentenbond describes the groups as low up to 8.4 degrees German hardness, medium up to 14 degrees German hardness, and high above that.

Almost nobody checks which group they are in. The result is that most households use the middle or even the highest dosage as standard, while their water falls in the lowest group. That costs money, it burdens the water unnecessarily, and it produces exactly the problem the maintenance advice then deals with: too much detergent causes biofilm.

Milieu Centraal arrives at the same point and goes one step further. Follow the dosage advice, they write, but also see whether you can manage with less, because that depends on how dirty the laundry is, the water hardness in your municipality and the load of the machine. In the Netherlands the water hardness is mostly soft to medium. And: laundry that is not too heavily soiled turns out to get reasonably clean even with water alone. Be especially careful with compact detergents not to use too much, because the environmental benefit is precisely that you need less of it.

The action is two minutes of work. Look up your hardness, read the table on the packaging, and adjust the cap or the dosing ball. Your machine stays cleaner, your laundry does not get less clean, and the chance that you need a descaler in a year drops with it. You see the same principle in every appliance that heats water; in our piece on the deposit in a kettle the same relationship between temperature, hardness and frequency is worked out.

What the manufacturers themselves prescribe

At this point it is honest to say what can and cannot be checked, because that is exactly where most articles about brands go wrong.

Siemens publishes a clear instruction: descale every 3 to 6 months, with a product intended for washing machines. Bosch, which comes from the same group of factories, sells its own descaler for it and refers to the same method. Those are two brands where you can read the source yourself.

For Miele, the brand most questions are about, it is different. The maintenance instruction differs per model and is in the manual for your type, not in a general page that applies to all machines. Every tip you come across online about a fixed button combination or a fixed product for a Miele therefore comes from someone other than the maker. That is not a detail: the Consumentenbond specifically states that manufacturers reject vinegar, soda and the dishwasher tablet because, in their view, they damage parts such as the rubber seals, and for a machine that is supposed to last 20 years that weighs more heavily than for a cheap appliance.

The rule that applies to every brand: get the manual out before you pour anything into the detergent drawer. If it names a product, use that. If it says nothing about descaling, stick to the general advice of 3 to 6 months with a descaler for washing machines, at 60 degrees, in an empty drum.

The machine smells: it is almost never limescale

A musty or sewer-like smell from the drum is the most frequently asked question about washing machines, and it is almost never a limescale problem. Limescale does not smell. What smells is the biofilm of grease, soap residue and bacteria that forms at low wash temperatures and with a door that is always closed.

The order that works:

1. First clean the door seal, the detergent drawer and the lint filter by hand. As long as those three are dirty, every programme you run has limited effect.
2. Then run an empty wash at 60 degrees, and explicitly do not choose the eco programme. For a stubborn smell and a machine used to liquid detergent, according to the Consumentenbond that may also be a boil wash at 90 or 95 degrees.
3. Use less fabric softener. Softener is grease, and grease is food for exactly the layer you are trying to get rid of.
4. From now on leave the door and the drawer ajar. This is the only measure that structurally removes the problem.
5. If the sewer smell remains, look at the drain instead of the machine. A drain hose without a water trap or a dried-out siphon lets sewer smell go straight into the drum; then no product will help.

Only when the smell is gone and something is still not right, such as a wash that takes a long time to heat up, is limescale the next suspect. In that order, not the other way around.

Why the limescale comes back, and what does solve it

Descaling is maintenance, not a solution. You remove the limescale from the element and the next wash the deposit starts again, because the calcium and magnesium are in the water you let flow in. Vitens describes the consequence precisely: because of limescale deposits on the heating elements more energy is needed to heat the water, and you also need more detergent. So it hits two cost items at once, every wash again.

There is only one route that tackles this at the source, and that is making the water itself softer. A water softener exchanges the calcium and magnesium for sodium, so that nothing is left to precipitate. That works for the whole home at once: the washing machine, the dishwasher, the boiler, the taps and the shower. How that works mechanically is explained in the article on ion exchange and regeneration.

Two honest caveats, because otherwise we do the same as the pages dismissed above. The first: a softener does not solve biofilm. Softer water means you need less detergent, and if you do not actually start dosing less, you keep exactly the same deposit problem. The second: a softener is an investment of around 1,700 euros for a simple unit up to well over 2,300 euros for a double cylinder, plus salt, and it does not pay for itself everywhere. With water in the lowest dosage group the difference is small. Vitens also points out that any treatment of tap water can bring risks, such as bacterial growth that affects smell and taste, so a unit that stands idle or is not maintained is not an improvement.

That is precisely why at PureAqua we start with your postcode and your household instead of with a quote. Are you in the low dosage group and do you mostly wash cold? Then the honest answer is that two descaling sessions a year and a better dosage are enough. Are you higher, and do you have a dishwasher, a boiler and a coffee machine alongside the washing machine that all cake up with limescale, then it adds up faster than you think.

Frequently asked questions

Conclusion

Separate the two jobs and it becomes manageable. Descaling is about limescale on the heating element, is done with a descaler for washing machines in an empty programme of 60 degrees or higher, and with Dutch water 1 to 3 times a year is enough instead of the monthly session you read about everywhere. Cleaning is about biofilm and smell, is done with a real wash at 60 degrees and with a cloth in the door seal, and comes up 1 to 2 times a month.

The two measures that deliver the most cost no product at all. The first is matching your detergent dosage to your own water hardness, using the groups up to 8.4 and up to 14 degrees German hardness as reference points. The second is leaving the door ajar after every wash. Do those two and an anti-limescale product is, according to the Consumentenbond, unnecessary and descaling becomes a half-yearly routine instead of a repair.

And if the limescale keeps bothering you throughout the home, then the problem is not in your machine but in your water. That is a different trade-off, with a different calculation, and you make it on the basis of your own hardness and not on the basis of general advice.