Shelf-life stability is a key product attribute
Preservatives are materials added to formulated products to inhibit bacterial and fungal growth.  Bacteria and fungi exist almost everywhere and wherever they find conditions favorable for growth they will grow. Unless formulated cleaning products provide extreme conditions such as very low or very high pH or very low water content, those products that are not protected by preservatives can grow these microbes. As cleaning products become more and more mild to the surfaces that they are used to clean, they provide better conditions for growing microbes that may naturally contaminate the product, increasing the need for preservation.

Secondary effects of contamination
Microbial contamination in a cleaning product can lead to a number of problems including the development of “off-odors”, development of “off appearance” including color changes and opacity changes, and loss of performance.  Performance impacts are typically caused by the microbes feeding off the surfactants and other active components of the formulation, by the loss of formulation stability due to pH changes associated with microbial metabolism and / or the microbes feeding off the components added to keep the formulation homogeneous.  Microbial contamination can also lead to problems with the product packaging including pressurization of the container, corrosion of metal containers such as aerosol cans, and in extreme examples, clogging of the product delivery mechanisms by biofilm.

In addition to these aesthetic and product performance concerns, there is also the risk that the contaminated product can be a reservoir of unknown microbial contamination leading to rapid contamination of a “freshly cleaned” surface.

A preserved product is not an antimicrobial product
Preservatives should not be confused with biocidal components added to formulations to impart an antimicrobial property to disinfectant and sanitizer products.  Preservatives are included only in amounts sufficient to protect the product itself from microbial contamination.