What is a common example of biofilm found in household settings?

Black staining around the bottom of a shower curtain is a common example of biofilm in household settings because it often consists of mold or mildew that thrives in moist environments. Biofilms are typically formed by colonies of microorganisms, such as bacteria and fungi, that adhere to surfaces in the presence of moisture and nutrients. In bathrooms, the conditions are ideal for such organisms to grow, leading to the development of visible stains often mistaken for dirt or wear.

In contrast, while green slime in swimming pools and algae in fish tanks also involve microbial growth, they are more associated with aquatic environments and are typically not classified as biofilms in the same way as the mold found around shower curtains. Residual chlorine in drinking water is a chemical compound used to disinfect water and does not contribute to biofilm formation; it actually works to prevent the growth of such organisms.