The following are causes for leaks:
- There is a fit problem, either gaping in the leg holes, or at the front at the top of the nappy.
- The nappy needs more absorption. If the inserts are saturated, then more absorption is needed. e.g. generally one insert will not last 3 hours.
A child changes feeding habits significantly from birth to toddlerhood. At birth the primary source of food is liquid, therefore it is expected that output will be similar. As a child gets older, they are able to hold their bladder and therefore can flood a nappy, in some situations the absorbency cannot keep up with that amount of liquid. Both situations require more absorption. See Adding Absorbency for options.
- The nappy needs to be changed more frequently, unless they are night nappies, most cloth nappies will only last 2 hours max before needing to be changed.
- The microfiber insert is saturated and compression is causing the liquid to seep.
- Have the inserts been prepped? New inserts absorb less than older ones.
The surface area of the fibers increases over time with washing (ie friction), the fibers become looser and micro piling occurs. The greater the surface area, the more absorbency potential.
Cotton, hemp and bamboo will continue building absorbency with use, change more frequently during this time. See New Nappies for more info.
- If the PUL has delaminated, cracked or otherwise become damaged, it will mean moisture will seep through from the inserts.
- Car seat belts can cause compression leaks.
- Another less seen cause is that the inserts are repelling water, which is due to using soap in the washing machine. See Detergents That Contain No Surfactants page for more info.
- Try using bamboo/hemp/cotton side up against the skin, rather than a stay dry layer, or in the pocket (if it is a pocket nappy). Microfiber should not go against the skin, it can cause irritation.
- If there isn’t enough room to add more inserts into the nappy, when using a low rise snapped OSFM (low rise meaning adjusted to being smaller), undo the rise snaps (ie. make it bigger) and add more absorbency. The additional room created will accommodate the added absorbency.
Urine output in children
Newborn babies have very small bladders, about 20-30mls, or just bigger than a metric tablespoon   . Children’s bladders get steadily bigger as they age, with a shift in how fast the bladder grows around age 2. Girls have bigger bladders than boys .
How babies pee also differs among children of different ages. Neonates urinate more often and at a higher pressure than older children  .
This pattern of when children urinate guides what absorbency is needed in reusable nappies.
Newborns need very small nappies (both because the child is small and because urine volumes are small) but the child will need changing frequently. This is also due to when the child will poo as well as how much and how often they pee. Many newborns poo before, during and after feeds. Typically newborns outwet nappies before they outgrow them, and more absorbency needs to be added to nappies or they will leak.
As children get older, their bladder capacity increases, and the amount they can pee increases, children require nappies with more absorbency. This peaks at about six months of age, which is the largest a child is when all of their nutrition is in liquid form.
After around age 2, children develop the ability to “flood” nappies, when they are dry for long periods of time (2-3 hours) and then can let go of a very large volume of urine all at once. Almost all OSFM nappies will require boosting for toddlers if a nappy is to last 2-3 hours.
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