Dry-cleaning, where little or no water is used, is normally practiced in environments where low water activity foods (e.g., flour, milk powder, biscuits, etc.) are manufactured. This is because the introduction of water could provide the means for microbial growth. In the absence of water particular care is required when dry cleaning to prevent the spread of allergen particles via the air. This could lead to product cross-contamination.
In wet-cleaning, water is used to remove soluble soils from the surface. This is the most common cleaning method in operations processing high water-activity foods (e.g., meat, beverages, etc.). The biggest drawbacks associated with wet cleaning in such environments are those related to the growth of microbes, and their spread (via water droplets, aerosols, standing water, condensation), and the high volumes of water used and wastewater generated.
However, in several food plants, controlled wet cleaning of smaller and dismantled pieces of equipment at a remote sanitation station is conducted, to minimise the risk of cross-contamination.