What Causes Ammonia Smell In Cloth Diapers? And How Do I Fix it?


Yes, poop and pee smell, but if your diapers smell so bad you can’t be in the same room with them just hours after they’re soiled, something is likely going wrong. It may sound crazy to beginners, but there are actually two types of smells that signal a problem: barnyard stink, and ammonia. We’re going to focus on ammonia smell here (and article on barnyard is forthcoming). 

So, what causes ammonia smell in cloth diapers? The short answer is ammonia smell is caused by one of three things: a wash problem (detergent buildup), warm and humid conditions (low-ventilation storage), or something happening in the body (including medical problem and just regular overnight wetting). 

We’re going to take a closer look at each cause here, along with how to fix it. 

Wait, but is Ammonia Smell a Big Deal? 

Yes.  Apart from being unpleasant — ammonia doesn’t just smell bad it can sting your eyes if strong enough– it can also cause severe rashes on a baby and can be the first sign of a very big problem, so paying attention is important.

What Causes Ammonia Smell in Cloth Diapers? 

As mentioned there are three main causes of ammonia smell in cloth diapers, but in the most basic sense, ammonia is when urea, one of the waste products found in urine (a byproduct of the breakdown of protein) breaks down further to ammonia.

Several things can cause this breakdown to happen faster, including:

  • Bacteria. Including higher than normal bacteria on your diapers thanks to things like buildup coming from a wash problem or hot and humid/ airtight/  lengthy storage.
  • Conditions that result in concentrated urine. Like overnight diapers, especially on bigger toddlers who are drinking less and sleeping longer, or certain medical conditions, which we’ll get to below. 

Ok, so now that you understand the underlying why, let’s look at each of the specific problems that might be causing your ammonia problem, and how to solve it: 

1. A Wash Problem (Detergent Buildup) 

By far the most common cause of ammonia smell that I’ve seen over the years of helping the thousands of cloth diaper beginners on the Cloth Diapers for Beginners Facebook group, is detergent buildup.

Detergent buildup is very common, especially when using generic wash routines (in fact it’s the main reason we developed the method to create personalized wash routines). 

The problem starts when you either overstuff your washer (“bulking” it up over the washing machine’s maximum weight capacity) use too much detergent for the amount of water level used by your washing machine or have water so soft it creates suds that can’t be washed away.

While most detergent sold today does work well under the low-water conditions of modern washing machines, even the most advanced detergent still needs enough water to move around what’s being washed, and get washed away. 

Without enough water, diapers may look clean because the heavy soil particles are the first to get rinsed away, but a layer of detergent and bacteria are left on the surface of the fabric. If the next time the diapers are washed there is still insufficient water/too much detergent used, another layer is deposited overtop of the last, trapping bacteria in. 

With every wash more and more detergent and bacteria are left on the diaper. Buildup gets thicker and thicker; smellier and smellier. If left unchecked, rashes quickly result and leaking can even happen. 

In other words, detergent buildup is a big problem, and the first tip-off is ammonia smell. 

How to Know if You Have Detergent Buildup (and How to Remove It)

I go into detail about how to test for and remove detergent buildup in this post, but testing for and removing detergent buildup from cloth diapers is actually pretty easy and straightforward. You can test for it by doing something called a “swoosh test.” This is essentially rinsing and “swooshing” around a clean diaper inside a bowl of water to see if suds come out. 

If you do that and see suds, bingo, detergent buildup is the problem and you can go ahead and go to the detergent buildup article here for all the info you need to remove it. 

One Important Next Step

After it’s removed, if you don’t want the ammonia smell to return, you’ll want to do one more important thing; revisit your wash routine and correct the root problem.

If you don’t have a personalized wash routine, consider creating one so that your diaper laundry has the right amount of detergent, water and dirty diapers for your washing machine.

To help you create a personalized wash routine, I have written the Cloth Diaper Wash & Care Handbook. You can learn all about the handbook and what is covers (hint: it’s not just laundry) here.

If you’re already using a personalized wash routine from the handbook and are getting detergent buildup, something is off. Make sure the numbers of dirty diapers you’re washing hasn’t changed drastically, and that you haven’t changed detergent, or moved (meaning your water may be different). If all things are the same and you’re still having problems, contact me (my email is at the back of the book) and I’ll be happy to help.

2. Warm and humid conditions (low-ventilation storage) 

As we touched on above, another cause of ammonia smell is your dirty diapers combined with lots of heat or humidity and time.

Urine naturally converts to ammonia after 24 hours, but with enough airflow, your diapers shouldn’t smell strongly of ammonia unless you’re up close. 

If however, your diapers are in an airtight storage container, or are stored in a hot and humid place that allows bacteria to grow quickly, that bacteria can speed up the process on top of providing conditions where the smell is allowed to gather and grow. 

How to Know if the Issue is Storage- Related (and how to fix it)

The following questions may help figure out if storage is your issue: 

  1. How long are you storing your diapers? It’s not recommended that you store dirty diapers for longer than 3-4 days no matter what storage container you’re using as bacteria growth can become a problem at that point. 
  2. Are they getting any airflow? Even the maximum 3-4 day storage recommendation is for storage containers that allow for airflow only. If you have an airtight diaper storage container, storing them longer for 1-2 days may be enough to allow bacteria to multiply fast enough to accelerate the production of ammonia from uric acid. 
  3. Are they being stored in a particularly hot and humid climate or space like a sunroom? If your diapers are being stored in a climate or room where heat and humidity are going to stimulate bacteria growth, this can also be the source of your ammonia problem. 

For all of these scenarios, washing more frequently and/or increasing the cool airflow on your diapers should significantly reduce bacteria growth, which will in turn reduce your ammonia stink.

3. Something Happening in the Body

The thing that makes dealing with ammonia in cloth diapers a bit frustrating, is that sometimes it’s not fixable with just a change to your wash routine or storage. Sometimes, ammonia smell is a sign of something going on inside the body.

That’s not to say that the cause is something to be alarmed about, often, as I touched on above, it’s just a case of overnight diapers on older babies creating conditions that result in concentrated urine.

Older babies who are drinking less breast milk or formula, and sleeping longer will have night time diapers that are very full with concentrated urine. These diapers will also be next to baby’s warm body all night long, heating them up. That’s why you often hear of ammonia smell only in baby’s nighttime diapers, and not in daytime diapers.

How to Fix Nighttime-Only Ammonia Smell

If you find your only problem with ammonia smell is at night, and there are no signs of detergent buildup and your storage meets all of the precautions we went over above, it’s may just be a case of concentrated urine at night.

To combat that smell, rinsing out night time diapers, diluting that urine, may be the best fix for you. Also consider giving baby some extra fluids before bed if maybe they aren’t in the habit of drinking much at night.

Other Medical Causes of Ammonia Smell

If baby has both daytime and night times diapers that smell of ammonia, you don’t have detergent buildup, and your storage is well-ventilated, there are a few other medical causes you should know about. These include:

  • Dehydration
  • Urinary tract infections
  • Diet (think asparagus) 
  • Kidney and liver maladies

(Sources: Healthline and Medical News Today)

Though I can not offer you medical advice of any sort, as I do not have any health-related expertise or credentials, I can suggest that a trip to your pediatrician to discuss the problem and just ensure that nothing serious is going on may be a good step.

In the meantime, before your visit, increasing your baby’s access to fluids may help that discussion with your pediatrician along. 

How to Get Rid of Ammonia Smell in Cloth Diapers

To review, if you want to get rid of an ammonia smell in your diapers, here’s the steps you can take:

  1. Check for detergent buildup. If you have it, remove it and create a new wash routine.  
  2. Make sure dirty diapers get lots of airflow while they’re waiting for wash day. 
  3. Rinse out overnight diapers in the morning
  4. If the problem persists, see a pediatrician

If you’ve tested your diapers and detergent buildup isn’t the cause, you have lots of airflow in your bin, and you’re getting ammonia smell from all your diapers, not just the nighttime ones, a trip to the pediatrician to be safe and sure it’s not a sign of a bigger health problem may be in order. 

Is there a Band-Aid Fix to Help Fix it in the Meantime? 

Yes. There are a few products to help you chemically neutralize the ammonia on the surface of your diapers. The two best I have been able to find are:

1. Bac-Out

My personal favorite odor removing spray is Bac-Out by Biokleen. It’s both economical, and works great not only for diapers but for pet odors as well.

Bac-Out is n enzyme cleaner pretreatment, so you’re going to want to use it after every diaper change, though some do use it in the pre-rinse cycle of their wash routine. If you’re using Bac-Out in your pre-rinse, add about ¼ to a full load of laundry.

According to the Biokleen website, Bac-Out is, ”A unique blend of live enzyme-producing cultures, botanicals, and plant-based surfactants. Great on pet accidents, wine, diapers and pails, laundry, and much more.”

2) Just Plain Old Vinegar

https://clothdiapersforbeginners.com/washing-cloth-diapers/vinegar-and-cloth-diapers/ Yes, vinegar is safe for cloth diapers (I have a full article about that here) and will neutralize ammonia.

Unlike Biokleen however, vinegar is not an enzyme cleaner, it’s just a mild acid. This means it will not remove the smell but change it back to a strong urine scent. While this is often better (especially in a pinch when you have vinegar on hand but not much else) it may not be a solution you want to stick to.

For more info on using vinegar to neutralize ammonia, click here.

Can I Use Bleach to Remove Ammonia Stink? 

I’ve been talking a lot about bacteria, so you might be thinking that bleach is a good option, but I caution against using this method when there are so many better, more natural ones available.

While bleaching will help with getting rid of bacteria, bleach has a high pH. Ammonia also has a high pH (as is detergent).

PH Scale

Bleach plus ammonia is therefore a very high pH combination (it also creates a toxic gas, but in the case of some in the washer with your diaper it wouldn’t be too much of a safety concern).

That high pH can cause rashes if not neutralized well enough before being placed on babies bum.

If you’ve already used bleach to try and correct an ammonia problem and baby is getting rashes, consider using a vinegar rinse to help neutralize the ph of your diapers.

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