Last Updated on October 5, 2026 by Umar Farooq
Cloth diapers take two cycles, not one. A short cool or warm cycle first to flush urine and residue out of the fabric, then a long hot wash on a heavy-duty setting with a full dose of ordinary detergent, finished with one or two extra rinses. Everything that goes wrong with a stash after that — ammonia, barnyard smell, fabric that stops absorbing, a rash nobody can explain — traces back to detergent, in one direction or the other.
Reusable nappies and cloth diapers are the same garment with different passports, and the routine below applies to both. The brand of nappy matters far less than how much water your machine is willing to give it.
Everything else in your laundry gets one wash; these get two
The reason is simple and nobody states it. A normal load arrives soiled; a diaper arrives saturated. If you put it straight into a main wash, the first thing your detergent meets is a drum of dilute urine, and it spends itself on that before it reaches anything that needs cleaning. The first cycle is disposal. The second is the actual wash.
Green Mountain Diapers, the most-cited independent reference in this niche, states the whole routine in four short sentences: “Run a cool or warm wash cycle with detergent first. Then hot wash with detergent on regular cycle. Extra rinse once or twice. That’s it. Easy!” Other sources run the first cycle cold and detergent-free. Both work, and the variable that matters is not the temperature of stage one — it is that stage one happens at all.
Note what the extra rinse is for, because it is not a nicety. Diapers hold more detergent in reserve than ordinary fabric does, which is the whole of the next problem on this page. Rinsing twice is the cheapest insurance available.
Before the pail: what comes off, and what can stay
Solids go in the toilet. A sprayer, a disposable liner or the edge of the toilet bowl all achieve this, and the method matters less than doing it before the diaper reaches the pail. Tide’s own guidance carves out the one genuine exception: “For breastfeeding babies you don’t have to worry too much about this step, because their poop is water-soluble!” Once solids start in earnest, so does the shaking.
Then store them dry rather than soaking, in a lidded plastic-lined pail or a zipped wet bag, and do not let the pail become an archive. Tide again: “For sanitary reasons, it’s best not to let dirty diapers sit for longer than two or three days, and this also helps prevent stains from setting.” Three days is also roughly how long it takes for the ammonia problem below to get going.
Staining is a separate question from cleanliness, and a clean diaper can still be a brown diaper. The sunlight trick that handles that — and the chemistry behind newborn stains — is covered in poop stains on baby clothes.
How to wash cloth diapers, stage by stage
Run this as two separate cycles with nothing else in the drum. Covers with waterproof PUL layers, inserts and flats can all go in together; the only thing that changes between brands is drying.
- Stage one — the flush. A short cool or warm cycle. Some routines add a small amount of detergent here, some run it plain; either is defensible. No fabric softener, ever, at any stage.
- Stage two — the wash. The longest, hottest cycle the diapers’ care instructions allow, usually heavy duty, with a full dose of detergent for a heavily soiled load. This is the cycle that cleans.
- Stage three — the rinse. One or two extra rinses. Check the final rinse through the door: if there are suds in the water, there is detergent still in the fabric.
- Dry. Line drying outside is ideal, and Tide notes that “the sun can help naturally bleach stubborn stains”. In a dryer, keep it to medium or low — PUL covers and elastic are the parts heat kills first.
| Stage | Temperature | Detergent | What it is for |
|---|---|---|---|
| Flush | Cool or warm | None, or a little | Getting urine and residue out of the way |
| Main wash | Hot, long, heavy duty | Full dose | The only cycle that actually cleans |
| Rinse | Cold | None | Getting the detergent back out again |
The load size is the step people get wrong. A drum stuffed to the top cannot move, and diapers that cannot move do not get clean; a half-empty drum of a dozen diapers is too light for the machine to read properly. Two-thirds full is the target, which for most households means washing every two to three days.
Detergent is the one dial, and it goes wrong in both directions
Almost every cloth diaper problem posted online is a dosing problem, and the two failure modes look nothing alike. Too little detergent leaves soil in the fabric, and the diapers come out smelling of nothing until they get wet, at which point they announce themselves. Too much leaves detergent in the fabric, and the diapers go stiff, stop absorbing, and start causing trouble on skin. Green Mountain is blunt about the second: “Detergent stuck in the diapers is high pH and it can cause a caustic burn on baby’s bottom which appears like a sunburn everywhere wetness touched skin.”
It is equally blunt about the first, which matters because the internet’s instinct is always to use less. “It does take using enough detergent to get things clean.” And it gives the only diagnostic worth knowing — the swish test. Put a clean, dry diaper in a bowl of warm water, swish and squeeze it for a few minutes, and watch the water. “If you see lots of detergent come out of the fabric, fix that problem. Some is ok but a lot is not.” The same test tells you nothing is wrong, which is just as useful. More on reading the signs of too much detergent in ordinary laundry.
Which detergent is where the sources stop agreeing, and the disagreement is worth seeing rather than averaging. Tide recommends its own oxygen-bleach powder and a pre-soak in it. Thirsties, which manufactures the diapers, lists “Bleach (oxygen or chlorine)” among the additives that “can void the warranty of your Thirsties products when used routinely”, and adds: “We also recommend avoiding detergents containing oxygen bleaches.” Both pages are live today. The detergent maker and the diaper maker are giving opposite instructions about the same product, and if a warranty matters to you, the manufacturer is the one holding it.
Ammonia, the barnyard smell, and a rash that is a pH problem
This is the part most cloth diaper pages get round to only as a symptom list, and it has a documented mechanism. Urine is largely urea, which is odourless. Bacteria carrying the enzyme urease convert it. A 2025 longitudinal study at the University of Bath describes the chain in one sentence: “Urease converts urea found in urine and sweat into ammonia. Ammonia directly damages skin barrier function, creating visible erythema” (faecal urease activity and nappy rash).
The second half of that sentence is the one that connects back to your washing machine. The same paper: “Ammonia also increases skin pH, damaging the natural acid mantle of the stratum corneum.” Alkalinity is the injury. And alkaline detergent residue left in a diaper does precisely the same thing from the other direction, which is why Green Mountain describes over-dosing as a caustic burn rather than an irritation. A baby with a rash across every area the wetness touched is being exposed to a high pH twice over.
Treat a strong ammonia smell on dry, clean diapers as evidence that the wash is not finishing the job, not as something to mask with scent. Hotter water, a fuller detergent dose, a longer cycle and a shorter interval between washes are the four levers, in that order. If the smell appears only on diapers that have sat in the pail for days, the pail interval is the problem.
Your HE machine is the obstacle, and there are three ways round it
Here is the appliance problem at the centre of all of this, stated by a diaper manufacturer rather than by a blog. Thirsties: “Diapers need a good amount of water to clean them properly, and HE machines use less water.” A modern front-loader is engineered to clean lightly soiled clothing in as little water as it can get away with, and a drum of saturated diapers is the single load it is worst suited to.
Thirsties lists three workarounds, and all three are about tricking the load sensor into asking for more water. “Use cycles such as heavy duty or bedding, or the ‘extra water’/’deep fill’ option.” “Select the Soak option to fill the washer with water, and then spin the water out. This will wet the diapers, making them heavier. In turn, that will trick the washer to use more water.” Or spray the diapers before they go in the pail, for the same reason. Your machine weighs the load and guesses; a wet load weighs more, so it guesses higher. It is a slightly undignified way to run an appliance, and it works. Nobody has to trick a twin tub washing machine, because you fill the wash tub yourself and the water level is your decision rather than a sensor’s.
One cycle to leave alone: the sanitise programme. Thirsties names “Sanitize cycles or other high heat cycles in HE machines” among the practices that void its warranty. What that cycle is actually certified to do, and on how few machines, is covered in the sanitise cycle explained.
Bleaching, stripping, and the lines a warranty draws
Routine bleaching is not a wash routine; it is a repair. Thirsties permits it as an occasional measure — “An occasional deep, disinfecting bleach-cycle can be beneficial, but you certainly don’t want to use bleach with every cycle” — and publishes the procedure: start with clean diapers, “Fill your washer half the normal capacity. Wash with hot water and 1/3 cup Clorox bleach and add an extra rinse cycle. Dry as usual.”
The sentence that follows is the one worth copying onto the wall above the machine. “After stripping the diapers, you will need to adjust your washing routine, or the stink issues will most likely be re-occurring.” A strip removes the symptom and leaves the cause exactly where it was.
The standing exclusions are short and the manufacturers agree on them: no fabric softener, no laundry boosters, no borax, no pure soap, and nothing scented. Fabric softener coats fibre, and coated fibre repels liquid — the one job a diaper has. Diaper creams are the other common contaminant, and Thirsties routes those to a sink rather than the washer: hand wash with dish soap, and “don’t use Dawn in your washing machine”.
FAQ
How often should you wash cloth diapers?
Every two to three days for most households. That interval is set by two things rather than one: a drum needs enough diapers to make a proper two-thirds load, and urine left sitting gives urease-carrying bacteria time to produce ammonia. Longer than three days and the ammonia starts winning.
Do you need a special cloth diaper detergent?
No. Thirsties says plainly that “most mainstream detergents are safe for cloth”, and lists Tide and Persil among them. What you need to avoid is anything with fabric softener built in, anything heavily scented, and — on Thirsties’ advice — anything with oxygen bleach, if the warranty matters to you.
Can you wash cloth diapers with other clothes?
No, and not for squeamish reasons. Diapers need a full detergent dose, the hottest cycle the fabric allows, and two extra rinses — a combination that is wrong for almost everything else in the house. Mixing loads means one of the two gets the wrong treatment.
Why do my reusable nappies smell of ammonia as soon as they are wet?
Because the wash is not finishing. A clean nappy that smells on contact with urine still has soil in it, and the usual cause is too little detergent, water that is not hot enough, or a cycle that is too short. Raise all three before reaching for a bleach soak.
Can cloth diapers go in the tumble dryer?
Inserts and flats, yes, on medium or low. Waterproof covers are where to be careful: heat is what delaminates PUL and kills elastic, and that damage is not recoverable. Line drying handles both, and daylight bleaches stains for free.
Put your nose in a clean diaper
That is Green Mountain’s test and it is better than any product: “Put your nose right up to a clean diaper and breathe in. If it doesn’t smell like nothing at all, or smell ‘clean’, it isn’t. Wash it again.” A diaper that smells of nothing has been washed properly and rinsed properly, and there is no scented product on the market that can fake it.
