Are Your Cloth Diapers Leaking? Here’s Why!

By April Duffy •  Updated: 07/02/24 •  18 min read

Do your cloth diapers leak? They shouldn’t. Cloth diapers are designed to keep messes contained, so if you have a leak, something is going wrong somewhere.

So why then are your cloth diapers leaking?

This may seem like a lot, but that’s because they’re actually just many variations on the big four problems that could be occurring: fit issues, absorbency issues, wash/product issues, and PUL issues.

In this post, I’m going to cover each one of the variations and how to fix it, and then jump into the different types of leaks (at night, through the legs, through the top, etc.) to pinpoint the most likely causes of your specific leak.

At the end, I have a handy cheat sheet for you to make it easy for you if your diapers are leaking!

17 Causes of Leaking Cloth Diapers and How to Fix Them

1. The Diaper Doesn’t Fit Correctly

A bad fit is the most common cause of leaks and the first thing you should check when leaks happen since it’s also the easiest to solve.

Fit Checklist

Properly fitting diapers should:

  1. Sit flush inside the bikini line crease, with no gaps.
  2. Lay as flat as possible around the waist. You should be able to fit a few fingers in the top but the diaper still shouldn’t shift down even when your little one is busy running all over the place
  3. Sit just below the belly button in the front
  4. Cover the top of the bum completely at all times in the back

How to Fix it:

This type of leak is most often caused at the changing table, so if you find you have a fit problem, do check out this post about how to put on a diaper so it doesn’t leak.

When adjusting the fit remember that elastics are made to stretch, so worry more about getting a snug fit than putting it on too tight. Often, when adjusting the diaper, we get worried about it being too tight, or worry when we see light pink marks after taking a diaper off. Those marks called “sock marks” and are completely normal, and actually a good thing because you know that diaper is snug.

Important note: While sock marks are normal, any red marks that are deep in color, have a white substance in them or are blistered or bubbled in any way, that’s something else and it should be checked out right away by a pediatrician click here for more information.

2. The Diaper Isn’t Being Changed Often Enough

I know, it sounds terrible saying, “Make sure you’re changing them enough.” But sometimes life gets in the way and we don’t realize that baby’s schedule has changed and maybe now they are wetting six times a day instead of four for example.

How to Fix It

Making sure to change baby every time they wet is a good start and a good way to prevent leaks and moisture diaper rashes.

Newborns will wet or soil their diapers every two hours or less. That length of time between dirty diapers will lengthen as your baby gets older, but ultimately it will depend on the baby, and as we all know, regressions, changes, and all kinds of life things can throw a wrench in our routines, so just make sure to check if baby’s diaper is wet regularly.

3. There’s Wicking Happening

If you’re using a two-piece diapering system, like prefolds, flats, or fitteds, and you find that you regularly have some of the absorbent fabric sticking out of the waterproof cover, it’s likely a wicking leak that’s your problem.

Wicking is when the liquid will transfer from the inside fabric of the diaper to the outside fabric of your baby’s clothes (or bedding, or whatever else it’s touching).

How to Fix It

Thankfully, fixing a wicking leak is super easy, it just requires being diligent at the changing table and making sure none of the absorbent fabric is sticking out of the waterproof cover.

4. The Elastics Need to be Replaced

Shot elastics can cause cloth diaper leaks as they make it very hard not to have gaps around the legs, which as we’ve learned causes leaks.

Here are a few photos of two cloth nappies. Both are the same brand, the same size, purchased roughly around the same time. There’s only one difference: the elastics of the teal diaper are shot (dried out and crackling when stretched).

It’s no wonder that shot elastics make such a huge impact!

Here are three things to check for if you think loose elastics might be the cause leg gaps and leak problems:

  1. Crunch. If the elastic feels hard or brittle, or if it crackles and crunches when you stretch it, the elastic is completely shot and absolutely needs to be replaced before using the diaper. There’s just no way around this one, as the elastic is so dried out and rotten that it has this crunch to it, it no longer has any use.
  2. Roll. Feel the elastic all around the leg, looking for any spots where the elastic is rolled rather than laying flat inside the seam. If you find rolled spots, or if the entire elastic is rolled this can cause gaps and you should consider changing the elastic.
  3. Stretch. A diaper elastic will stretch and snap back a good two inches or more when fresh, an elastic with not much pop back may also cause problems.

How to Fix it

If your elastics are crunchy, rolled, or don’t have much stretch, replacing them may be the key to getting a nice proper fit around the leg crease to prevent leaks.

If you have bumGenius pocket diapers or all-in-ones, pay special attention to your elastics as bumGenius diapers are notorious for needing elastic replacement regularly.

5. The Diaper is Overstuffed

Overstuffing your diapers with absorbency can also cause problems by making it impossible for the leg elastics to reach your baby’s leg crease, especially if using pocket diapers where space is limited by the lining.

How to Fix it:

Changing the type of cloth diaper inserts you’re using for less bulky ones may be an option, but often it comes down to changing the type of diapers you’re using. At night (and during the day for some very heavy wetters) more absorbency is often needed than what you can stuff into a regular pocket diaper.

Choosing a two-piece cloth diapering system, like prefolds, flats, or fitteds under a cloth diaper cover, will allow you to pack in more absorbency without compromising the seal around your baby’s legs.

6. There’s Pressure on Your Diaper Causing Compression Leaks

As I mentioned above, overstuffing your diapers is not only a problem because it can lift the leg elastics out of the bikini line, but it can also cause “compression leaks.”

Just like a sponge, diaper inserts are able to hold much more than most materials, but if you squeeze them, liquid will come out. Making sure the diaper is not overly squeezed in any way will help prevent your cloth diapers leaking from compression.

Overstuffing, tight onesies, and even a snug car seat belt pressing baby down for a long period, can all cause compression leaking.

Microfiber inserts are particularly prone to compression leaking over firmer fabrics like hemp and cotton.

How to Fix It

To solve compression leaking, just do what you can to lighten the load. Swap out microfiber inserts and charcoal bamboo inserts for thinner, more absorbent inserts like hemp and real bamboo(see the chart above). Adding onesie extenders to baby’s onesies (I’ll post a link below for more info), and planning for situations where compression leaks are likely, like the car seat on long trips (I’ll also post a car seat liner) will all help.

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07/23/2024 08:22 pm GMT
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7. Make Sure You Have Enough Absorbency in Your Cloth Diapers

It sounds obvious, but many times leaks happen because baby is releasing XX oz of liquid into the diapers, but the inserts only hold X oz of liquid.

If you’re changing baby after a leak and notice that all the inserts are completely soaked, this is likely the problem.

How to Fix It

If you’re already changing after every wetting, adding more inserts may be necessary. As baby grows (along with their output), the number of your inserts and boosters may need to grow along with them. When in doubt, add another insert and see.

8. Make Sure Your Inserts are Absorbing Quickly Enough

Adding more inserts as your baby grows is important, but so too is the kind of inserts you’re adding.

Some types of inserts, specifically natural fibers like cotton, hemp, and bamboo (and the natural-fiber blends, like zorb) are more absorbent than others. On the other hand, some inserts, like microfiber inserts and cotton are faster absorbing.

As you might expect, making sure you’re using high-absorbing, natural fiber inserts is going to help prevent cloth diapers leaking from the volume of urine, but sometimes, for a few babies, the speed of the urine can also be a concern.

Some babies “flood” their diapers, meaning they wet so fast and with so much pressure, that a diaper with only slow-absorbing fibers, like hemp, may not be able to soak it all in fast enough before it floods out of the diaper.

How to Fix It

Here’s a handy chart to help you figure out what you’ve got in your stash to work with:

Insert TypeAbsorption AmountAbsorption Speed
Microfiber/Bamboo blend💧💧💧💧💧💧

As your baby grows and changes you likely need to start pairing high-absorption fabrics with high-retention fabrics to match your baby’s output.

9. The Diapers Weren’t Prepped Properly

When you first get new diapers, it’s important to wash them before use. However, if your diapers or inserts are made from natural fibers like hemp, and occasionally cotton, there are natural oils present that need to be fully washed out for them to reach their full absorbency and absorbency speed.

How to Fix It

If your diapers or inserts are made from hemp, very important to prep your new diapers and inserts by washing them several times. If you’re using cotton inserts or prefolds and notice repelling (see below), this can also be the problem and you can wash them several times before use to get them to their full absorbency.

10. Fabric Softeners Are Causing Repelling 

The cardinal rule in cloth diaper wash and care is to avoid fabric softeners, including liquid fabric softener, dryer sheets, and added softeners in your diaper detergent.

Why are softeners so bad? Because they work by coating fabrics in a waxy oil that makes them feel soft, but over time, also creates a water-resistant layer that repels liquid. If your diapers start repelling liquid, instead of absorbing it, you have a big problem.

How to Test if Your Diaper is Repelling

Testing to see if your diaper is repelling is very easy. Just take a clean and dry diaper, and drop some water on it. If the water beads up and doesn’t absorb after a few minutes or with some light touching of your hand (as some synthetic diapers need) then they aren’t able to absorb liquid properly.

How to Fix It

If you have a buildup of fabric softeners on your diapers, you’ll need to “strip ” them. Stripping is using a sodium carbonate product to literally strip oily substances off the surface of the fabric. Information on how and when to strip diapers is here.

11. Diaper Creams Are Causing Repelling 

While the most common cause of repelling is fabric softeners, waxy diaper creams can also cause repelling. If your diaper cream has been causing bad cloth diaper stains that don’t wash away, that’s a good sign this is your problem.

If liquid is being repelled off of your diaper (the opposite of absorbing) then it will have nowhere to go but out of the diaper in any small gap it can find. The result is your cloth diapers leaking.

How to Test if Your Diaper is Repelling from Diaper Creams

You can easily test your diaper to see if it repels. If a clean, dry diaper does not absorb liquid after a few minutes or with gentle pressure on the diaper, (as some synthetic diapers require) they are not able to do so.

How to Fix It

It’s time to “strip” your diapers if there’s a buildup of rash cream on them. By stripping, you’re literally removing oily substances from the fabric surface with sodium carbonate. Detailed information on stripping diapers can be found here.

12. Hard Water is Causing Repelling

If you discover you have very hard water after watching your cloth diapers slowly become dingy and smelly (barnyard smells usually accompany hard water issues) it could be that minerals from hard water (calcium and magnesium) could be keeping your diapers from absorbing. This type of repelling is rare since your water would have to be INCREDIBLY hard and the smell would knock you out before repelling would happen, not to mention you’d probably see some irritation on your baby’s skin, but it is possible.

How to Test if Your Diaper is Repelling

If a clean, dry diaper doesn’t absorb liquid dropped on it after a few minutes or when gently touched, (as some synthetic diapers do), it’s repelling.

How to Fix It

You can remove hard water minerals with sodium carbonate by stripping. You can find detailed info on stripping diapers here.

13. Using Too Much Detergent is Causing Repelling

If you’re using a generic wash routine from a cloth diaper blog like Fluff Love University, or one of the many cloth diapering Facebook groups, the chances are good that you’re using too much detergent. a Detergent buildup can also happen, but again, you’d be tipped off by a strong ammonia smell or ammonia diaper rash long before your diaper starts repelling.

How to Test for Detergent Buildup

Luckily, testing for detergent buildup is also quick and easy. Just take a clean and dry diaper and submerge it into a bowl of warm water. If you see suds or a film develop on the top of the water after a few minutes of swishing it around and squeezing it a few times, you have detergent buildup.

How to Fix It

Detergent buildup needs to be rinsed completely off your diapers (and your washing machine) with water. Instructions on how to remove detergent buildup from cloth diapers can be found here.

14. You’re Using the Wrong Kind of Detergent / Soap for your

In addition to using too much, using the wrong type of detergent can also cause repelling issues that lead to leaky diapers.

Specifically, homemade DIY diaper “detergents” and soaps, Charlie’s Soap, and soap nuts all create and leave behind a soap scum film when used in the low-water conditions of modern washing machines, which can build up on the surface of diaper fabrics causing smelly diapers and leaks.

How to Fix It

If you’ve been using homemade DIY diaper “detergents” and soaps, Charlie’s Soap, or soap nuts to wash your cloth diapers you’ll need to strip them clean even if they aren’t yet repelling to avoid bacteria growth. You can find detailed info on stripping diapers here.

7. There’s a Break in The Waterproof Layer

Most diaper covers, and shells (meaning the outside of AIO diapers) are made of Polyurethane Laminate (PUL).  PUL is a fabric (typically polyester but sometimes cotton or polyblend) that’s been adhesive heat laminated on one side to a layer of polyurethane film. PUL is waterproof, which is why it’s used on the outside of cloth diapers to keep wetness in.

It should come as no surprise then that a break in the waterproofing will mean leaks.

How to Know if There’s a Break in Your PUL

It’s fairly easy to tell when PUL is the cause of the leak as the wetness won’t seem to come from any of the openings, but instead from random places on the surface of the diaper. The diaper will just be slowly getting wet on the outside.

Here’s a quick video showing you how to look for cracks in your shell (video courtesy of The Towers):

Can it Be Fixed?

Unfortunately, cracked PUL can’t be fixed, so it means you’ll need to invest in a new cover or diaper.

16. The PUL is Delaminating

Like cracking, delaminating is when the waterproof layer of your cover or PUL diaper becomes compromised and creates a leak.

How to Know if Your PUL is Delaminated

Here’s a quick video showing what PUL delamination looks (video courtesy of Darlings Downunder):

Can it Be Fixed?

Unfortunately, there’s no way of repairing delamination once it happens and it’s time to retire it from nappy duty. Information can be found here about how to extend the life of your diapers if you find this to be a problem for you.

17. There’s a Problem with The Seams

If your seeing Leaking at the stitching or seams of the PUL cover it may not be a crack or delamination at all.

If your diaper’s brand new, it could be that it was never “sealed” at the seams where the sewing machine created holes. Most larger cloth retailers sell their diapers pre-sealed, but occasionally something happens, and smaller cloth diaper operations may not pre-seal their diapers.

How to Fix It

To seal a PUL cover at the seams, dry it in a hot dryer (I know, I’m contradicting basic cloth diaper 101 advice, but it will be just this once) for about 15-20 min.

If that doesn’t work, it may unfortunately mean the PUL is compromised and can’t be saved.

Using Where Your Cloth Diapers Leak to Determine the Cause

So now that we know the solutions for leaking cloth diapers, let’s take a look at some specific types of leaks. This will help us narrow down the most likely cause of your leak, so you don’t have to waste time fixing things that aren’t broken.

Why is My Cloth Diaper Leaking from the Legs?

If your cloth diaper is leaking from the legs, the most likely cause is wicking or a poor fit, which can be caused by not putting the nappy on properly (cloth is different than disposables), overstuffing the diaper, or shot elastics.

If your diaper is as snug to the bikini line as you can get it, but you’re still getting leaks from the legs, it may be a slow absorption or buildup issue giving the liquid to time to get through even the tiniest of openings between the leg and diaper.

Why is My Cloth Diaper Leaking from the Top?

If the leak is coming from around the waist or back of the diaper, the cause is likely the diaper fit, or you have a boy and his penis is pointing up.
If you have a boy, make sure he’s pointing down before you do up the diaper.

If you already make sure he’s pointing away from the top of the diaper before you do it up, or you have a little girl, check that the diaper is sitting nice and high on the waist, covering the entire bum area and that you have enough absorbency added.

Why are My Cloth Diapers Leaking at Night?

Night-time leaks are almost always due to not having enough absorbency for the long stretch of time your baby is sleeping. Unfortunately, the diapers that get you through the day probably won’t work overnight.  

I’ve written full instructions on how to use cloth diapers at night time successfully here.

What if My Cloth Diaper Leaks When Baby Sleeps on Their Side

If your overnight diaper is only leaking when baby sleeps on their side, first, do make sure you have enough absorbency added, but also check the fit and consider either switching to a fitted diaper or adding some fast absorbing material to the diaper.

Grab a Free Leak Checklist PDF (No Email Required)

Now that you know all there is to know about cloth diaper leaks, grab this printable leak checklist to keep near your change table. Whenever you get a leak use it to help you recall what you learned here and solve those leaks fast!

Cloth Diaper Leak Checklist

Click here to get a Leak Checklist PDF that will help you pinpoint the cause of your cloth diaper leak, fast!

April Duffy

April is the founder of Cloth Diapers for Beginners and author of The Cloth Diaper Wash & Care Handbook. Since 2015, April has helped well over 75,000 parents and caregivers cloth diaper their children through this website, her book, her YouTube Channel, and the Cloth Diapers for Beginners Facebook Group.