Swim diapers can be reusable and disposable. They are not intended to be absorbent. Typically, it is assumed that a swim diaper should be absorbent, or contain urine, like a regular diaper. However, the purpose of a swim diaper is only to contain solid waste; the lack of absorbency prevents the swim diaper from swelling up with water.
Often reusable swim diapers are lined with a fiber which encourages the solid waste to cling to the fiber without an absorbency layer. A snug fit in the legs and waist are key to function. Brands such as Splash About and The Honest Co. and Beau & Belle Littles  utilise tightly knit polyester or neoprene as their material. The disadvantages of a reusable swim diaper is that they must be washed to be reused. On the other hand, a disposable swim diaper is only partially biodegradable and repeated purchases may cost more than reuse. One brand of disposable swim diapers is Little Swimmers, marketed under the Kimberly-Clark Huggies brand. Procter & Gamble produces the rival brand Pampers Splashers. Both are sold in three sizes: small (16–26 lb or 7–12 kg), medium (24–34 lb or 11–15 kg) and large (over 32 lb or 14 kg+). Due to their design for swimwear, they are not as absorbent and not intended for regular diapering. Currently, there are no disposable adult swim diaper options.
Swim diapers at public pools
Some public pools require swim diapers for use by young children and the incontinent out of hygiene concerns. For the same reason, other pools do not allow swim diapers at all. Sick children who are not potty-trained and do not wear swim diapers may be responsible for the transmission of e. coli from fecal matter.
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- "Swim diapers may not keep pool water clean, UF experts say". University of Florida. Retrieved 20 October 2015.
- "University of Florida News - Swim diapers may not keep pool water clean, UF experts say". News.ufl.edu. 2007-07-10. Retrieved 2010-09-08.