Why are my cloth diapers leaking?

by Boop Baby

Leaks are a pain, but they are pretty easy to diagnose and solve to make your cloth diapering journey easy and painless The main causes of leaks with cloth diapers are (in order of most to least common):

  1. Not enough absorbency (usually only pee leaks)
  2. Fit (Pee and poop can both leak)
  3. PUL or elastic problems
  4. Repelling (very uncommon)

In this post, we will go through all of these possibilities to help you diagnose your leak problem and also solve it. If you don’t want to read, we have put together a very handy flowchart below to help you. Otherwise, read on!

You can also watch our YouTube video about leaks here!

Flowchart about leaks. Click to expand.


The most common cause of leaks is absorbency. This simply means there isn’t enough absorbent material to soak up all of what your baby is putting into the diaper. The simple answer is to put more into the diaper to absorb it. You can add Thirsties hemp/cotton inserts into any diaper for additional absorbency without a lot of additional bulk. Hemp babies and Smart Bottoms also make great additional inserts, some absorb even more than Thirsties. You can shop for all the addition inserts at Boop Baby here.

There are some important things you need to know about cloth diaper inserts, as they are not all created equal. Much of this can be changed depending on the quality of fabric and how many layers of absorbency are in the insert. Just speaking in terms of general inserts, on average, the following is true:

Fabric Type Properties
Microfiber Absorbs very fast , highly absorbent , synthetic (man-made) fibers , prone to compression leaks , least expensive
Cotton/organic cotton Absorbs fast , very highly absorbent , natural fibers , second least expensive,
Bamboo/Bamboo terry Absorbs fast , very, very highly absorbent , natural fibers , more expensive
Hemp Absorbs slowly , extremely absorbent , natural fibers , more expensive
Overview of different diaper fabrics and how fast and how much they absorb

The least expensive, and probably most common diapering material for absorbency, is microfiber. It is cheap to produce, and is synthetic (polyester) material. It holds a lot of liquid, and absorbs quickly. One downside to microfiber is compression leaks. If microfiber is totally saturated (full of liquid), and someone presses on it (or a onesie is putting pressure on the diaper, or a carseat, or something), then the microfiber will release some of the liquid it is holding, like a sponge when you squeeze it.

Most of the grey market diapers you can buy (such as Alva, Babygoal, ohbabyka, lil bit, Happy Beehinds, and other diapers that cost about $7-8) cut costs by cutting the quality of their microfiber. These inserts are only three layers, but they have long fibers, which makes them not as absorbent (3 layers) and more vulnerable to large compression leaks (long fibers). I do know of some parents who have successfully cloth diapered with these brands, but you will be the most successful and have the trimmest fit if you use different inserts entirely. You can add a hemp insert to it, but the amount the microfiber will hold is not worth the bulk of the space the insert takes up inside the diaper. You will have much better luck using those inserts as a reusable swiffer pad or scrubber and put prefolds or flats in your diaper instead. It will add a lot more absorbency and you won’t get those compression leaks that are so common in the grey market brands.

The brands that we carry at Boop Baby that are microfiber are higher quality than the brands I have just talked about. There are usually more layers of microfiber in the insert, and they don’t have the super long fibers that cause compression leaking. Most of the quality brands have a useful microfiber insert that won’t have its bulk increased a lot by adding an additional insert. If it is an AIO or AI2 type diaper, you can put the insert underneath the absorbency to add to it.

Cotton, bamboo, and hemp are good, absorbent options for cloth diapering. If you have a baby who is leaking through the brands we carry at Boop Baby, just add absorbency to it in the form of additional inserts and you should be good to go. If leaking is extreme due to heavy wetting, replacing inserts with prefolds is still a valid option.

Grey market diapers have inserts that claim to be bamboo, or charcoal bamboo, or other natural fibers, where they have a thin bamboo outside, but are microfiber inside. These diapers are manufactured in countries without ethical rules regarding the labeling of products. With this in mind, they are still going to have the leak problems that microfiber inserts have with these kind of diapers, and you will have a better cloth diapering experience repurposing those inserts and using prefolds, flats, or other absorbency instead.


Fit can be a common cause of leaks, and is pretty obvious if the inserts are barely wet when the diaper has leaked. With a bad bit, poop can even leak out, which is never a good thing . It means the liquid has simply fallen out of a gap in the leg or at the belly. Here are the three places you should check for gapping and a good fit:

Tummy and legs are the most common places for fit issues to arise.

One common question new cloth diapering parents have is about lines left on baby’s legs or back from the cloth diaper elastic. As long as the lines are about on par with sock lines, and aren’t purple or very deep, you don’t need to worry. Cloth diapers are just clothing with elastic in it, like socks. They leave more lines because they have better elastic than the disposable ones. You should be able to fit about two fingers between the elastic and baby’s skin if the tension of the elastic is right.

Two fingers between the diaper elastic and the skin is a good fit that will hold in leaks and keep baby comfortable.

Check for any noticeable gaps around the legs and tummy. Some brands of diapers can handle gaps at the tummy better than others, I like to look for a PUL (laminated fabric) strip along the top of the inside of the diaper or elastic in front above the snaps. This allows for shifting of the tummy panel and inserts without causing leaks, and can improve fit.

Many brands fit well without these extra features, but if your baby gets tummy gaps that cause leaking, these are good ones to try. Pictured: Thirsties, Smart Bottoms, Applecheeks

If you have fit leaks, the location of the leak is a pretty good indicator of where the gaps in your fit are. Check our fit guide for more assistance.

Note: If you have gaps at the stomach that do not cause leaking or wetness on your baby, don’t worry about it. Only take this step if the gapping is causing leaking.

Shot PUL or Elastic

This is a less common reason to leak, but is pretty easy to diagnose. If the outside of the diaper is wet, then the liquid is soaking through the laminated fabric. This is more common in grey market diapers, as they use lower quality materials to cut costs. It can happen with very old non-grey market brands, or PUL can be damaged by washing in “extra hot” water, or even on hot if your water heater is turned up too high.

Shot PUL can have the laminated part completely separating from the color part, it might look like a plastic bubble. If it’s an AIO and you can’t see the PUL, it’ll feel bubbly or like there’s a layer of plastic inside.

PUL may also be damaged if it has scratches or cracks in it. If you have those in your PUL and it is leaking through to the outside, the PUL is shot. There’s no real fix or remedy from damaged PUL, as it would require deconstructing and reconstructing the diaper to fix it, and would not be worth the cost to do so.

Elastics, on the other hand, are easy to replace. You can help your elastics last longer by not stretching them while still hot (like out of the dryer), let them cool down before putting stress on the elastic by pulling it. Shot elastics will not have much recovery when you stretch them, and might even make a crunching noise. Elastics can be replaced fairly simply with some sewing, or you can try to find a local seamstress to do it. The process is a bit more complex for AIOs and some covers than it is for pocket diapers. If you have sudden gapping around the legs on a diaper that never did that before, or it looks significantly longer when laid out flat next to another diaper of the same brand, you might have to replace the elastic.

An Alvababy cloth diaper with shot elastic on one side


This is the least common issue causing leaking, and is isolated mainly to diapers with a synthetic inner (like microfleece or microsuede) that have been exposed to rash cream that is not safe for synthetic fabrics. Rash creams like Desitin, Vaseline, or other petrolium-based skincare products, will adhere to the synthetic fabric inside pockets and some all-in-ones. That will make it so liquid no longer can go through the synthetic fabric and reach the insert. This can be diagnosed by seeing a completely dry insert and having leaking coming from the diaper. It just means there’s something making it so the synthetic fabric won’t allow liquids through.

If this happens to you, your diapers are not ruined, you just need to do some work to fix the ones that are repelling. Dawn brand dish soap is really good for oil and other products that might have built up in your diapers. Apply dish soap and scrub gently with a brush. Rinse, and see if water will go through the microfleece. If not, repeat the process until the liner is free of build up.

To avoid this problem in the future, use petrolium-based products only on natural fabrics (like cotton prefolds or AIOS) and use cloth-friendly rash creams only on your synthetic fabrics.

I hope this helps you pinpoint the reason your diapers are leaking, or helps you stop them from leaking before they start! If you have any questions, leave them below or message us on Facebook or e-mail us at hello@boopbaby.com.

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