We tend to think of the dishwasher as a bastion of hygiene, given that it washes our plates using copious amounts of hot water and detergent. Yet, the machine itself harbors a far less pristine microbiological reality within its nooks and crannies.
A study published on January 12, 2018, in the peer-reviewed journal *Applied and Environmental Microbiology*—conducted by a team of Danish, Slovenian, and Belgian researchers—analyzed the rubber seals of 24 household dishwashers across Europe. The findings were unequivocal: bacterial genera such as *Pseudomonas*, *Escherichia*, and *Acinetobacter*—known to include opportunistic pathogens—were present in virtually all samples collected. Even more striking, the fungus *Candida* (associated with fungal infections) was detected in every single dishwasher tested—a 100% prevalence rate.
This result is explained by a scientific paradox documented by the researchers themselves: the extreme conditions inside a dishwasher (high temperatures, highly acidic or alkaline pH, high salt concentrations, harsh detergents, and the mechanical force of sprayed water) should, in theory, prevent any form of microbial life from thriving. Yet, certain groups of microorganisms have proven capable of withstanding all these stressors simultaneously, establishing themselves permanently in these seemingly hostile conditions—particularly on the door seals, an area rarely cleaned by users. While the researchers note that the risk remains generally low for healthy individuals, these microorganisms can pose greater problems for the immunocompromised—a population that, according to the study, is steadily growing.

What this task actually entails

Emptying and putting away the dishwasher involves removing clean dishes at the end of a cycle and returning them to the cupboards, while taking a moment to quickly inspect the appliance's general condition. Allow about 10 minutes for this task—a chore that needs to be done as often as the household runs a wash cycle.

Tips to limit microbial growth

Wiping down the rubber seal with a dry cloth after every cycle—a quick step that is often overlooked—significantly limits the buildup of residual moisture that fosters the growth of these microorganisms, according to the study's researchers.
Avoiding opening the dishwasher immediately after a cycle ends—while it is still hot and humid—reduces the release of potentially spore-laden aerosols into the kitchen air. Letting the appliance cool for a few minutes before opening it is a simple habit recommended by the scientists who conducted the research.
Regularly cleaning the filters and spray arms located at the bottom of the unit effectively complements seal maintenance; these areas also accumulate food residue and limescale, creating conditions that favor the long-term establishment of these microbial communities.

Even an appliance that appears as "clean" as a dishwasher harbors—according to this 2018 scientific study—a very real microbial diversity in its most hidden nooks and crannies. A simple wipe of the seal with a dry cloth after each cycle remains the most effective way to limit this proliferation, without requiring any special effort.