Category: Gear

A microfibre cloth that pushes water around instead of picking it up, or that leaves a fine smear on glass it used to clean perfectly, has almost never worn out. It has been coated. Three things do the coating, and all three happen in the laundry: fabric softener, which deposits a deliberately water-repellent film; detergent and hard-water residue, which packs the spaces the cloth works by; and dryer heat, which glazes filament tips that are finer than anything else in your wash. The cloth looks identical afterwards. That is the whole problem — the failure is invisible, so it gets blamed on the cloth being cheap.

The rules that prevent it are printed by the manufacturers and are unusually consistent: wash microfibre on its own, use a liquid detergent for coloureds, never fabric softener, no bleach and no optical brighteners, keep to the temperature on the label, and dry on low heat or not at all. One maker goes further and publishes a number nobody else does — a maximum detergent pH. This article explains what those instructions are protecting, where they come from, and how to tell whether a cloth is recoverable or finished. Home Clean Manual has not laundered these cloths under controlled conditions and makes no claim to have done so; what follows rests on manufacturer product documentation, a granted patent specification describing how the textile is built, and published water-hardness standards, all cited so you can check them yourself. There is more on how to judge cleaning textiles as technical products on the Gear hub.

Microfibre does not absorb water. That single fact explains everything else

The intuitive model — a cloth is a sponge, it soaks water into its fibres — is wrong for microfibre, and every laundry rule follows from how wrong it is.

Cleaning-grade microfibre is a bicomponent filament: polyester and polyamide extruded together in a wedge or pie-slice cross-section, then split apart mechanically or chemically so that one thick filament becomes many very fine ones. Vileda Professional’s own technical page on microfibre puts the fineness at less than 1 dtex — decitex, the mass in grams of 10,000 metres of the filament — and describes the result as roughly one hundredth the diameter of a human hair. The same page distinguishes classic microfibre, split sixteen times, from its MicronFibre construction, split thirty-two times, and explains the division of labour between the two polymers: the polyester component attracts water while the polyamide repels it, which is what allows the cloth to lift and hold soil in water without leaving the drying marks a wetter, simpler textile would.

A German patent specification for a microfibre wipe cloth, DE 102 26 937 A1 (published 8 January 2004), sets out the same thresholds in the flat language of a technical document: microfibre is defined as fibre with a fineness below 1.0 dtex, with material below 0.3 dtex classed as ultra-microfibre; the preferred cloth has a basis weight of at least 120 g/m², optimally 150–200 g/m². And it states the point that reframes the whole subject: microfibre itself cannot absorb water. What the cloth does is hold water in the enormous interstitial space — the air chambers and fine pores — created by packing very fine filaments together, drawing it in by capillary action. Greenspeed’s product page for its Original microfibre cloth quantifies the effect from the other end: “high absorbency, 6 times its own weight.”

So the working part of a microfibre cloth is not the fibre. It is the gaps, and the sheer number of filament edges presented to the surface. Both are microscopic and both are open. Fill them, coat them, or fuse them and you have a cloth that weighs the same, feels similar and no longer works. That is the mechanism behind every instruction below, and it is why “buy better cloths” is usually the wrong answer to a cloth that has stopped performing.

Fabric softener is the single most documented mistake

Manufacturers do not usually agree about anything. They agree about this, and they put it in short imperative sentences.

Kärcher’s microfibre floor cloth set for the EasyFix nozzle — order number 2.863-259.0 — carries the whole care instruction in two clauses on its product page: “Maschinenwäsche bis 60 °C möglich. Keinen Weichspüler verwenden.” Machine washable up to 60 °C; use no fabric softener. SharkNinja’s care guidance for Shark steam mop Dirt Grip pads says the same thing and, unusually, gives the reason: avoid bleach, powdered detergent and fabric softeners, because these “may damage or leave a coating on the Dirt Grip pads that will reduce their cleaning performance and absorbency”. Greenspeed’s care instructions for its Original cloth arrive at the same place from the detergent side, ruling out products containing bleach or optical brighteners.

The chemistry is not mysterious. Fabric softeners are built on cationic surfactants — molecules with a positively charged head that binds to the slightly negative surface of laundered fibre, leaving a fatty tail pointing outwards. That outward-facing fatty layer is the product working exactly as designed: it lubricates fibres so cotton feels soft and does not build static. It is also, functionally, a thin water-repellent film. Applying a deliberate hydrophobic coating to a textile whose entire operating principle is capillary uptake into open microscopic space is a direct contradiction, and the cloth loses on both counts — the film repels water and the softener residue occupies the gaps that were supposed to hold it.

Three practical consequences follow, and the second and third catch people who have already stopped using softener:

• Dryer sheets do the same job by another route. They exist to transfer softening agents onto fabric using dryer heat. A cloth washed correctly and then tumbled with a dryer sheet has been softened.
• A softener dispenser that has been used for years holds residue. If the machine’s dispenser drawer and siphon are coated, a rinse cycle can still deliver some of it. Cleaning the dispenser is part of a general machine service — the same job covered in how to clean a washing machine.
• “2-in-1” and “with conditioner” detergents contain softening agents by design. Read the front of the bottle before you conclude you have stopped using softener.

Detergent: the pH ceiling nobody quotes

Every article on this subject says “use a mild detergent”. One manufacturer publishes an actual limit, and it is the most useful single number in this whole topic.

Greenspeed’s care instructions for its Original microfibre cloth specify washing at 60 °C with a detergent for coloured fabrics, and then set out constraints: do not use washing powder — use a liquid detergent; do not use detergents containing bleach or optical brighteners; and do not use detergents with a pH higher than 10. The same page tells you to rinse cloths before washing to remove residual cleaning chemicals, and to wash microfibre separately from other fabrics where possible. It also claims the cloth is “washable at least 600 times”.

Each of those constraints is protecting something specific:

• The pH ceiling of 10 is the one to write down, because it quietly invalidates a large amount of popular internet advice. The standard folk remedy for “dead” microfibre is to boil it in a solution of washing soda (sodium carbonate) or to add soda to the wash. A working solution of sodium carbonate sits above pH 11. Polyamide — the half of the split pair that does much of the soil-trapping — is the more chemically sensitive component of the two, and strongly alkaline conditions at temperature are not kind to it. A manufacturer that publishes a numeric limit is telling you where its warranty of performance ends, and the folk remedy is comfortably outside it.
• Liquid rather than powder is about undissolved solids. Powder detergents carry insoluble or slowly-soluble builders and fillers; a textile whose working structure is a dense mat of sub-micron gaps is an efficient filter for exactly that kind of particle. Shark’s pad guidance names powdered detergent alongside bleach and softener for the same reason.
• No optical brighteners is more elegant than it sounds. Optical brightening agents are fluorescent dyes whose entire function is to deposit on the fibre and stay there, converting ultraviolet light into visible blue so fabric reads as whiter. They are, by definition, a coating you are paying to apply. On a colour-coded cleaning cloth they achieve nothing and add residue.
• No chlorine bleach. Both Greenspeed and Shark exclude it. Beyond the polyamide question, bleach destroys the colour coding that the cloths exist to carry — and colour coding is a hygiene control, not decoration.
• Rinse before washing. Cloths come out of service loaded with whatever chemistry you were cleaning with. Putting an alkaline degreaser into a wash alongside a pH-limited detergent means you no longer know what pH the cloth is sitting in.

Temperature: follow the label, not the internet

The numbers that manufacturers publish for their own products are lower and narrower than the advice you will read elsewhere. Kärcher’s floor cloth set: machine wash up to 60 °C. Greenspeed’s Original cloth: 60 °C with a colour-safe liquid detergent. Shark’s pads: warm water with liquid detergent.

Professional cleaning textiles rated for higher temperatures do exist, and the reason they exist is disinfection rather than cleaning performance — a laundry process for a healthcare setting has to kill organisms, not just remove soil. If the label on your cloth carries a higher figure, that figure is the one to follow. What you should not do is assume that hotter is generically better. Repeated high-temperature washing accelerates the loss of the split-filament structure that does the work, and the durability figures manufacturers publish are tied to a specific process, not to any process.

Which brings us to the most quietly revealing sentence found anywhere in this research. Vileda Professional’s page for the MicroTuff Base cloth does not simply claim a durability number — it states the test conditions: “High durability up to 300 washes, tested at internal lab at 60°C chemical thermal disinfection.”

Read that carefully. The figure is (a) an internal laboratory result, not an independent one; (b) measured under chemo-thermal disinfection — a laundry process that uses a disinfectant chemical at a moderate temperature instead of relying on heat alone; and (c) specific to 60 °C. It is a perfectly honest disclosure, and it is far more informative than the bare numbers most brands print. But it also means that Vileda’s “up to 300 washes” and Greenspeed’s “at least 600 times” are not comparable quantities. They are two internal claims measured against two undisclosed protocols, and no page — this one included — can tell you which cloth lasts longer, because the test methods are not published. Anyone who tells you otherwise is guessing.

Drying is where cloths die fastest

Both of the makers whose full care text was available push you away from the tumble dryer rather than merely capping its temperature. Greenspeed: avoid mechanical drying as much as possible, to extend the product’s life. Shark: dry Dirt Grip pads on low heat, or line dry.

The reason is a matter of surface area and mass. Polyester and polyamide are thermoplastics — they soften before they melt. A filament under 1 dtex has an extraordinary ratio of surface to mass, so it reaches the dryer’s air temperature almost instantly and has essentially no thermal inertia to protect it. At the tips of a split filament, where the material is finest, softening is enough to round over and fuse neighbouring filaments together. That reduces the edge count that does the cleaning and closes the capillary gaps that do the absorbing. A heat-glazed cloth has a characteristic feel: slick and slightly plasticky rather than grabby, and it skates across glass instead of biting.

Two more drying rules follow from the same physics. Never iron microfibre — an iron plate is far above the softening range and will glaze a cloth in one pass. And separate microfibre from cotton in both the wash and the dryer, which manufacturers put in terms of cross-contamination and lint: cotton sheds prodigiously, microfibre is a superb filter, and a cloth loaded with cotton lint smears. If you have ever washed microfibre with towels and then found it leaves fluff on a mirror, that is not a defect in the cloth.

Hard water is doing half the damage, silently

There is a residue source that has nothing to do with what you put in the machine. Calcium and magnesium ions in hard water react with anionic surfactants in ordinary detergent to form insoluble calcium and magnesium salts — the classic “soap scum” — and those deposit in the textile during the wash. On a cotton towel you might notice slight stiffness. On a textile that works by keeping microscopic gaps open, it is a direct attack on the working structure.

As with steam appliances, the fix begins by replacing the adjective with a number. The US Geological Survey classifies water hardness, as calcium carbonate, at soft 0–60 mg/l, moderately hard 61–120, hard 121–180, and very hard above 180. Germany does it in statute: § 9 of the Wasch- und Reinigungsmittelgesetz defines Härtebereich weich as “weniger als 1,5 Millimol Calciumcarbonat je Liter”, mittel as 1.5 to 2.5 mmol/l, and hart as “mehr als 2,5 Millimol Calciumcarbonat je Liter”, and obliges water suppliers to tell customers which band applies “mindestens einmal jährlich” — at least once a year.

Two things are worth taking from the comparison. First, the bands do not line up: one millimole of calcium carbonate per litre is roughly 100 mg/l, so German law does not call water “hard” until about 250 mg/l, while the USGS calls anything above 180 mg/l very hard. A supply at 200 mg/l gets two different adjectives depending on which document you are reading. Second — and this is the part that matters for laundry — notice why German law imposes that disclosure duty at all. It exists so that consumers can dose detergent correctly, which is why German detergent packs print dosing tables by hardness band. Dosing to hardness is the mainstream, legally-supported practice in one of Europe’s largest markets and is almost unknown in English-language laundry advice.

The practical rule for cleaning textiles: find your figure, dose to it, and resist the instinct to add extra detergent because the cloths are dirty. Overdosing in soft water leaves surfactant residue in the fabric; under-dosing in hard water lets calcium soaps deposit. Both end in the same place — a cloth full of solids that used to be full of air.

Is this cloth recoverable, or finished?

There is a fast, non-destructive test that follows directly from the mechanism, and it costs nothing.

Take the cloth dry and put a single drop of water on it. On a healthy cloth the drop is gone on contact — the capillary structure pulls it in before it can form a bead. On a coated cloth the drop sits proud for a second or two, or spreads reluctantly. On a badly softened or glazed cloth it beads and can be rolled around the surface. That is a direct read on whether the capillary space is open, which is the only property that matters.

What the result tells you:

• Absorbs instantly, but smears on glass. The structure is intact; the contamination is on the surface. Usually lint from being washed with cotton, or greasy soil the last wash did not lift. Rewash alone, liquid detergent for coloureds, no softener, and add a rinse.
• Hesitates, then absorbs. Partial coating, typically softener residue or detergent overdosing. Wash again on its own at the label temperature with a reduced detergent dose and an extra rinse. Line dry. Several cycles may be needed, since you are washing residue out of a structure designed to hold things.
• Beads and stays beaded after two or three correct washes. The cloth is either heavily softened or heat-glazed. Glazing is not reversible — it is a physical change in the filament. Demote it to garage, boot-room or outdoor duty rather than trying to rescue it.
• Absorbs fine but feels thin and slick, and the edges are shedding. This is genuine wear. Retire it. Shark’s own guidance treats three to four months as normal service life for its steam mop pads under regular use, on the basis that “dirt particles, grease friction and repeated washing can cause the fibres to break down”. Pads and cloths are consumables with a service life, and pretending otherwise costs more in redone work than the replacements do.

Colour coding is a control system, and bleach destroys it

The colours are not there to look tidy. They exist to make cross-contamination visible to a supervisor from across a room, and they are one of the reasons professional cleaning textiles are bought in quantity rather than singly.

Vermop, the German professional cleaning-systems maker, publishes its scheme for surface cleaning cloths and their containers: blue for general surface cleaning, furniture and offices; green for surfaces in hospitals, operating theatres and kitchen areas; yellow for sanitary surfaces — bathroom, sink, tiles; and red for toilets and urinals. Vileda Professional supplies its MicroTuff Base cloth in the corresponding four colours: blue, red, yellow and green.

Two cautions. The scheme is a convention, not a universal standard — the blue/green pairing in particular varies between countries and between healthcare and food-sector guidance, so a cloth’s colour tells you what a specific organisation decided it means. And the scheme only works if the colours survive laundering, which is one more argument against bleach and optical brighteners. At home the useful version is simpler and still worth doing: one colour that never leaves the bathroom, one that never enters it. The reasoning behind keeping surfaces separated, and why a single cloth fails even within one room, is set out in the two-cloth method.

A wash routine that satisfies every instruction quoted here

Nothing in this list is invented. Each line traces to a manufacturer instruction cited in the sources below.

1. Rinse cloths before they go in, to get residual cleaning chemistry out of the fabric (Greenspeed).
2. Wash microfibre on its own — not with cotton towels, not with cleaning rags of other fibres (Greenspeed).
3. Liquid detergent for coloureds, not powder, with no bleach and no optical brighteners, and nothing above pH 10 (Greenspeed; Shark also excludes powder and bleach).
4. Dose to your water hardness, and do not add extra because the load looks dirty (USGS / § 9 WRMG bands for the number).
5. No fabric softener, ever, and no dryer sheets (Kärcher; Shark).
6. Wash at the label temperature — 60 °C is the figure Kärcher and Greenspeed publish for the products documented here (Kärcher; Greenspeed).
7. Add a rinse if your machine allows it. You are trying to leave nothing behind.
8. Line dry, or tumble on low. Avoid mechanical drying where you can, and never iron (Greenspeed; Shark).
9. Store dry. A damp cloth folded in a caddy grows biofilm, which is the source of the smell people blame on the cloth being “old”.

Frequently asked questions

Can I wash microfibre with my towels to save a load?

No, and it is the most common self-inflicted wound in this topic. Greenspeed’s instruction is to wash microfibre products separately from other fabrics where possible. Cotton sheds lint continuously; microfibre is an efficient filter with an enormous internal surface. The cloth comes out loaded with fibre it will then deposit on the first pane of glass you touch. Separate them in the dryer too.

Do I need a special “microfibre detergent”?

Nothing in the manufacturer instructions gathered here requires a branded microfibre detergent. What they require is a set of properties: liquid rather than powder, formulated for coloureds, free of bleach and optical brighteners, and below pH 10. A plain liquid colour detergent generally satisfies all four. The specialist products are convenient, not obligatory.

Can I use vinegar to strip a cloth that has gone water-repellent?

An acid rinse addresses one specific failure — calcium and magnesium soaps deposited from hard water — because those deposits dissolve in acid. It does nothing about fabric-softener film, which is not a mineral, and nothing at all about heat glazing, which is a physical change. So it is a targeted tool for one cause rather than a general revival treatment. Check your cloth’s own care instructions first, keep it well away from anything containing bleach, and treat a cloth that still beads after a correct rewash as finished.

Why do my microfibre cloths smell even after washing?

Usually biofilm, in the cloth or in the machine. Cloths stored damp are an ideal substrate, and a washer run consistently at low temperatures with a softener-coated dispenser develops its own residue that reinfects every load. Dry cloths fully and openly between uses, wash at the label temperature rather than reflexively at 30 °C, and service the machine itself — the drawer, the door seal and the filter — as set out in how to clean a washing machine.

What does “300 washes” or “600 washes” on the packaging actually mean?

Less than it looks like. Vileda Professional’s MicroTuff Base page discloses its conditions — up to 300 washes, tested in an internal laboratory at 60 °C chemo-thermal disinfection — which is more transparency than most brands offer, and it also shows why the numbers cannot be compared. Greenspeed’s “at least 600 times” is measured against a protocol that is not published. Different temperatures, chemistries, load weights, spin speeds and end-point definitions produce wildly different counts. Treat these as durability claims made under the maker’s own conditions, not as a specification you can hold them to.

Is microfibre actually better than cotton, or is that marketing?

They fail differently, and the difference is structural rather than promotional. Cotton absorbs water into the fibre itself and holds it; split microfibre holds water in capillary space between filaments and presents a very large number of fine edges to the surface. That structure is what makes microfibre effective with little or no chemical and what makes it capable of leaving glass dry rather than merely wet. It is also what makes it fragile in the ways described above — a cotton cloth is largely indifferent to fabric softener, and a microfibre cloth is ruined by it. The advantage is real, and it is entirely conditional on the laundry.

If your steam mop has a small tank, a pump you can hear ticking, and it makes steam within a minute of switching on, its manufacturer almost certainly wants distilled or demineralised water in it. If it has a pressurised boiler you fill through a screw-in cap, that takes several minutes to come up to heat and holds pressure while you work, its manufacturer may well tell you the opposite — that distilled water will stop the machine reading its own water level. Kärcher’s steam cleaner FAQ says exactly that, in writing. Bissell’s and Shark’s support pages say the opposite, also in writing. Neither is wrong. They are describing different machines.

So the honest answer to “distilled or tap?” is: it depends on how your machine senses and heats water, and the only document that settles it is the one that came in the box. This article explains the mechanism behind each instruction, what limescale actually does inside a steam mop, what the manufacturers specify for descaling — including the part numbers of the consumables — and the order in which to check a mop that has stopped steaming. Nothing here rests on testing. Home Clean Manual does not own these machines and has not run them; the assessment rests entirely on manufacturer service documentation, published order numbers, and published water-hardness standards, every one of which is cited so you can check it.

Two completely different machines are sold as “steam mops”

The category name hides an engineering split that decides almost every maintenance question you will ever ask about the thing.

The pump-fed flash heater. This is the common upright stick format. A small plastic tank holds water at atmospheric pressure. A pump — usually a solenoid pump, the component that makes the rhythmic ticking noise — pushes water in tiny doses through a heated aluminium block or coil, where it flashes to steam and exits immediately. There is no reservoir of steam and no pressure vessel. Heat-up is fast because you are only heating a passageway, not a tank of water. Bissell’s own support page for the PowerFresh Slim instructs you to fill the tank “with distilled or demineralized water” using the supplied cup, and adds flatly: “Do not use any chemicals in the water tank.” Shark’s care guidance for its steam mops is the same shape — “We recommend using distilled water in the tank” — and goes further on additives, which we come back to below.

The pressurised boiler. This is the cylinder-format steam cleaner and its upright derivatives. Water goes into a sealed metal boiler, is heated as a body of water, and generates steam under pressure that is released through a valve when you press the trigger. It takes minutes rather than seconds to be ready, and it needs to know how much water is inside it. That last requirement is the whole reason for the contradiction. Kärcher’s steam cleaner FAQ, under the question “Darf der Dampfreiniger nur mit Leitungswasser befüllt werden?” (“May the steam cleaner only be filled with tap water?”), states: “Bitte verwenden Sie kein destilliertes Wasser, da damit die Füllstandserkennung im Kessel nicht funktioniert.” — please do not use distilled water, because the fill-level detection in the boiler does not work with it.

That sentence is the key to the whole subject, and it is worth unpacking because no English-language cleaning article seems to have bothered. Fill-level detection in a boiler of this kind is typically done with electrodes: a small voltage is applied and the appliance watches for a completed circuit through the water. Water conducts because of the dissolved ions in it — calcium, magnesium, sodium, bicarbonate, chloride. Distillation and deionisation remove exactly those ions. Genuinely pure water is a poor conductor, so an electrode-based level sensor sitting in it sees an open circuit and concludes the boiler is empty. The machine either refuses to work or, worse, misreads a full boiler as dry. The manufacturer is not protecting a consumables business here; it is protecting a sensor.

A flash heater has no such sensor sitting in the water path. It has a tank you can see through and a pump that either has water or does not. Nothing in it needs the water to conduct. Which is why the same substance — pure H₂O — is recommended by one manufacturer and prohibited by another.

Architecture	How to recognise it	What the maker’s water instruction tends to be	Where the scale collects
Pump-fed flash heater	Small tank, audible ticking pump, steam within about a minute, no pressure cap	Distilled or demineralised preferred; tap water tolerated	Inside the narrow heater passage and the steam jet
Pressurised boiler	Screw-in maintenance or safety cap, minutes to heat, holds pressure, often a separate refill tank	Tap water; pure distilled may defeat fill-level detection	On the boiler walls and heating element
Boiler with a descaling cartridge	A removable cartridge in the fill tank plus an indicator lamp	Tap water, filtered by the cartridge on the way in	Intercepted in the cartridge — until it is exhausted

Kärcher sells that third variant: a replaceable descaling cartridge, order number 2.863-018.0, listed on Kärcher’s own accessory page at 56 × 56 × 163 mm and specified as fitting the SC 2 Upright, the SC 3 family (EasyFix, Upright, Premium and Deluxe variants) and the SCV 4 Steam Vac. It treats the water on the way in rather than asking you to descale the boiler afterwards. This is the pattern the Gear hub calls “the consumable is the product”: before you buy anything with a cartridge in it, find the cartridge’s order number and confirm it is still stocked, because the machine’s usable life is the cartridge’s availability.

What limescale actually does inside the machine

Scale is not dirt. It is calcium carbonate that has come out of solution, and the reason it forms in heated appliances rather than in your cold pipes is that calcium carbonate has *inverse* solubility — it becomes less soluble as water gets hotter. Heat the water, drive off dissolved carbon dioxide, and the bicarbonate in solution converts to carbonate that has nowhere to go but onto the hottest surface available. The US Geological Survey puts the consequence plainly in its water hardness explainer: when hard water is heated, “solid deposits of calcium carbonate can form”, and that scale “can reduce the life of equipment, raise the costs of heating the water, lower the efficiency of electric water heaters, and clog pipes.”

In a steam mop the hottest surface is either the boiler element or the wall of the flash-heater passage, and the geometry is unforgiving. A flash heater’s passage is narrow by design — that is how it transfers enough heat into a small slug of water fast enough to boil it. A deposit measured in fractions of a millimetre is a meaningful percentage of that bore. The observable symptom is not usually a sudden death. It is a gradual reduction in steam volume, then intermittent spitting of hot water instead of vapour as the passage’s heat transfer degrades, then nothing. Owners describe it as the mop “getting weaker”, which is exactly what a progressively narrowing orifice would produce.

There is a second, meaner failure that scale causes in flash heaters: the pump keeps working perfectly. You can hear it ticking, so the machine sounds alive, and the natural conclusion is that the pump is fine and the heater has failed. Often neither has failed — the *path* is blocked, downstream of the pump, and the pump is dutifully pressurising against an obstruction. This is why the diagnostic order later in this article puts “remove the floor head and test for steam at the outlet” before any conclusion about the heater.

“Hard water” is an adjective. Get the number instead

Every steam mop instruction that says “if you have hard water, use distilled” is passing you a decision without giving you the threshold. Worse, the word does not mean the same thing in different countries, and the gap is large enough to change your answer.

The USGS classification, in milligrams per litre of calcium carbonate, runs: soft 0–60, moderately hard 61–120, hard 121–180, and very hard above 180.

Germany’s classification is set in law rather than by a survey. Section 9 of the Wasch- und Reinigungsmittelgesetz (WRMG), the German detergents act, defines three bands: Härtebereich weich is “weniger als 1,5 Millimol Calciumcarbonat je Liter” — less than 1.5 millimoles of calcium carbonate per litre; mittel is 1.5 to 2.5 mmol/l; and hart is more than 2.5 mmol/l. The same paragraph obliges water suppliers to tell customers which band applies to their supply “mindestens einmal jährlich” — at least once a year, and again whenever the band changes other than temporarily.

Convert and the mismatch is startling. One millimole of calcium carbonate per litre is about 100 mg/l, so the German “hard” band does not begin until roughly 250 mg/l. A household supply at 200 mg/l is very hard under the USGS bands and merely mittel — medium — under German law. If you have ever wondered why German appliance manuals seem relaxed about tap water while American ones push distilled, part of the answer is that the two documents are using the same adjective for different numbers.

Two practical consequences. First, find your actual figure rather than an adjective: in the US it is in your utility’s annual Consumer Confidence Report, usually as mg/l or as grains per gallon (one grain per gallon is 17.1 mg/l, so the USGS “very hard” threshold of 180 mg/l is about 10.5 gpg). In Germany and much of the EU your supplier is required to publish the band. Elsewhere a cheap aquarium or pool test strip will get you close enough to choose a side. Second, use the number as a decision rule, not a feeling: at the soft end, the manufacturer’s tap-water permission is genuinely safe; in the upper bands, on a flash-heater machine whose maker already recommends demineralised water, the recommendation stops being optional in any practical sense.

Descaling: what the manufacturers actually specify

Descaling is where owner forums and manufacturer documentation diverge most sharply, and the divergence is expensive.

On a pressurised boiler, Kärcher’s FAQ describes descaling as routine maintenance rather than a repair, and names its own consumable: the procedure begins “Entkalker-Lösung mit Kärcher Entkalker-Pulver (Bestellnummer: 6.296-193.0) anmischen” — mix a descaler solution using Kärcher descaler powder, order number 6.296-193.0. The published sequence is to empty the boiler, introduce the solution, allow it to act for several hours, then empty and rinse twice with clear water before refilling. Two details in that sequence matter and are routinely skipped in blog write-ups: the solution goes into a machine that is *not* running, and the boiler gets two clear-water rinses, not one. A descaler is an acid; leaving residue in a vessel that will shortly be pressurised and heated is not a neutral act.

On a cartridge machine, the maintenance task is not descaling at all — it is replacing a part before it stops working. Kärcher’s cartridge (2.863-018.0) is the consumable that stands between hard tap water and the boiler, and the machine signals when it is spent. This is the single most commonly ignored maintenance item on these products, because a cartridge that has stopped working looks identical to a cartridge that is working.

On a pump-fed flash heater, read the manual before you introduce anything at all, because the manufacturers of these machines are noticeably stricter about what may enter the tank. Bissell’s support instruction is unambiguous — “Do not use any chemicals in the water tank.” Shark’s steam mop care guidance is more explicit still, and names the household remedy directly: “Make sure you only add water to the tank – chemicals or cleaning solutions (including vinegar) may damage the steam mop and could be unsafe.”

No steam: a diagnostic order that follows the documented failure points

Work through these in order. The sequence is deliberately arranged so that the cheap, documented causes are eliminated before you conclude anything about the heater — which is the component people replace machines over.

1. Power and ready state. Bissell’s troubleshooting for the PowerFresh Deluxe describes an indicator that blinks for roughly 30 seconds after plug-in before going solid. A machine that has not finished its heat-up is not a machine with a fault. Wait for the steady light.
2. Steam actually switched on. Several models have a discrete steam on/off control separate from mains power, and Bissell’s own sequence lists pressing it as a step.
3. Water, and the machine’s orientation. This is the step that catches the most people, and it is in the manufacturer’s own troubleshooting: on the PowerFresh Deluxe, water cannot feed into the pump unless the machine is upright. A mop reclined against a worktop while it heats may simply have an air-locked pump. Stand it up and try again.
4. Remove the floor head and test at the outlet. Bissell’s documented diagnostic splits the fault cleanly here: if steam appears with the foot removed but not with the foot attached, the fault is in the foot, and the published remedy is to order a replacement foot rather than service the machine. If there is no steam even with the foot off, the fault is upstream. This one test separates a cheap part from an expensive one, and almost no third-party troubleshooting article includes it.
5. The pad. A pad that has gone hard with detergent residue or mineral deposit will hold steam against the plate instead of releasing it, which reads as “less steam”. Shark’s guidance is to replace Dirt Grip pads roughly every three to four months in normal use, because “dirt particles, grease friction and repeated washing can cause the fibres to break down” — a pad is a consumable with a service life, not a permanent fitting.
6. Scale, last. If the machine is out of warranty, has always run on hard tap water, has never been descaled, and steams weakly rather than not at all, scale is the probable answer — and the remedy is the manufacturer’s published descaling procedure, not an improvised one.

The floor is the other half of the question, and its document wins

People search for water type when the more consequential question is whether the machine should be on that floor at all. Two documents govern a steam mop on a hard floor: the appliance manual and the flooring manufacturer’s care instructions. They are not equal in authority, because the appliance maker is not the party that warrants your floor.

It is worth quoting the appliance side accurately, because it is routinely misreported in both directions. Kärcher’s steam cleaner FAQ, answering “Darf der Dampfreiniger auf Laminat und Parkett verwendet werden?”, permits it with a specific and limiting condition: “Dampfreiniger können Sie für die Reinigung von versiegeltem Laminat oder Parkett (nicht geölt oder gewachst!) verwenden.” — you can use steam cleaners on sealed laminate or parquet, not oiled or waxed. The same answer sets a technique constraint: “Achten Sie darauf, dass möglichst wenig Feuchtigkeit auf dem Boden zurückbleibt, indem Sie mit dem Gerät nicht zu lange auf einer Stelle stehen bleiben und die Dampffunktion nicht dauerhaft betätigen.” — make sure as little moisture as possible is left on the floor, by not lingering in one place and not holding the steam function on continuously.

Read that as what it is: a conditional permission with a moisture ceiling attached, not a blanket endorsement. The seal is the barrier; an oiled or waxed finish is not a barrier in the same sense, and the machine’s job is to leave the floor damp for seconds, not wet for minutes. And it remains the appliance maker’s view of the appliance. If your flooring manufacturer’s care sheet excludes steam — many do, and the exclusion is usually about vapour migrating through joints into the core rather than about surface heat — that document governs, because that is the warranty you would be claiming under. Check the floor’s paperwork first. There is more on this conflict, and on how to think about hard-floor tools generally, on the Gear hub and in the Deep Cleaning procedures.

The pads are the running cost, and washing them wrong undoes the machine

A steam mop’s cleaning performance is a partnership between the steam and a microfibre pad, and the pad is the half you control. It is also the half that people quietly destroy in the laundry.

The instructions are printed and consistent across brands. Shark’s care guidance for Dirt Grip pads: machine wash in warm water with liquid detergent, and avoid bleach, powdered detergent and fabric softeners, because these “may damage or leave a coating on the Dirt Grip pads that will reduce their cleaning performance and absorbency”; dry on low heat or line dry. Kärcher’s own microfibre floor cloth set for the EasyFix nozzle, order number 2.863-259.0, carries the same instruction in two short sentences on its product page: “Maschinenwäsche bis 60 °C möglich. Keinen Weichspüler verwenden.” — machine washable up to 60 °C, use no fabric softener.

The mechanism is worth knowing, because it explains why a pad can look perfect and clean badly. Split microfibre works by capillary action in the spaces between very fine filaments; fabric softener is a cationic surfactant designed to deposit a hydrophobic film on fibre surfaces. Applying one to the other is a direct contradiction of the pad’s operating principle. Powdered detergent contributes undissolved builder particles that lodge in the pile. High dryer heat glazes the split filament tips. None of these leave a visible mark, which is exactly why the failure gets blamed on the machine.

Frequently asked questions

Can I use water from a filter jug instead of buying distilled?

A jug filter reduces some hardness but does not deionise; the water leaving it still carries plenty of dissolved ions. On a boiler machine with fill-level detection that is a point in its favour — it will not blind the sensor the way distilled water can. On a flash heater it is a partial measure: better than untreated hard tap water, well short of the demineralised water the maker recommends. Check whether your machine has a purpose-made cartridge or filtration bottle in its accessory list before improvising, since that part is designed around the machine’s own tolerances.

Is “demineralised” the same as “distilled”?

Not by process, but close enough in effect for this purpose. Distilled water is condensed steam; demineralised (deionised) water has had its ions stripped by ion-exchange resin. Both are very low in the calcium and magnesium that form scale, and both are poor electrical conductors — which is why both fall foul of a conductive fill-level sensor. Manufacturers that recommend one generally accept the other; Bissell’s support pages name “distilled or demineralized water” together.

Does softened water from a water softener solve the problem?

Partly, and not in the way people assume. An ion-exchange softener swaps calcium and magnesium for sodium. Sodium salts are far more soluble and do not build the same hard carbonate scale, so a softener does reduce scaling. But the water is not demineralised — the total dissolved solids are comparable, so it still conducts, and it can still leave deposits as it boils dry. Softened water is a reasonable input for a boiler machine; it is not a substitute for demineralised water where the maker has specified demineralised.

How often should a steam mop be descaled?

Manufacturers tie the interval to water hardness and to the number of boiler fillings rather than to the calendar, which is why a single universal figure does not exist and any article giving you one has invented it. The two variables to apply are your measured hardness — see the USGS and WRMG bands above — and how many tanks you have put through the machine. On cartridge-equipped machines the machine tells you, and the correct response is to replace the cartridge, not to stretch it.

Can I add a fragrance or a cleaning solution to the tank?

Both Bissell’s and Shark’s published guidance say water only. Bissell: “Do not use any chemicals in the water tank.” Shark: only water, with chemicals and cleaning solutions “(including vinegar)” named as potentially damaging and unsafe. Some machines have a separate scent-disc or fragrance-pad fitting that sits outside the water path — that is the sanctioned route, and it exists precisely because the tank is not.

My mop steams but the floor stays wet. What is wrong?

Usually the pad, not the steam. A pad that has been softened, bleached or hot-dried loses the capillary structure that lifts moisture off the floor, so the steam condenses and stays there. That is also the condition Kärcher’s own floor guidance warns against — as little residual moisture as possible on sealed laminate or parquet. Wash the pad correctly, or if it fails the water-drop test (a drop of water on a dry pad should vanish on contact rather than bead), retire it. Shark treats three to four months as a normal pad life under regular use.