Infection control professionals have long known that bathrooms are hotbeds of microbial activity, but a new study published in the Journal of Hospital Infection (May 2025) has confirmed toilet flushing can release Clostridioides difficile into the air and onto surfaces in ways far more hazardous than previously understood.

The research, which evaluated the microbial risks of toilet flushing in hospital settings, revealed two key transmission pathways – fomite-to-hand-to-mouth contact and inhalation of bioaerosols. Both pose serious infection threats, particularly in high-use facilities such as hospitals, where C. difficile infections can be life-threatening.

One flush alone can eject C. difficile into the air at concentrations of up to 29.5 colony-forming units per cubic metre. Worse still, droplets from the flush can contaminate high-touch surfaces including flush buttons, toilet seats, faucets and door handles. The bacteria are stubborn adversaries, persisting even after aggressive disinfection protocols that achieve a 4.4 log reduction in microbial load.

The problem does not end there. The fine mist of droplets generated during flushing also increases humidity levels within the bathroom – an environment that helps bacteria stay viable longer. In both scenarios, the risk of inhalation and ingestion exceeds safety thresholds set by the World Health Organisation (WHO) and the United States Environmental Protection Agency (EPA), prompting urgent questions about current hygiene strategies.

Visual evidence shared in Howie Clean It: Restroom Edition and further illustrated through high-speed video footage underscores just how far and fast germs can travel from a single flush. These findings are not just alarming – they are a call to action.

Cleaning professionals, infection control teams and facility managers must now reconsider long-standing bathroom design norms and hygiene practices. Strategies such as lid-down flushing, installing better-ventilated toilet cubicles and adopting self-disinfecting surfaces could all play vital roles in mitigating risk. Cleaning protocols demand an immediate upgrade to address contamination beyond the toilet bowl – targeting all high-touch points with high-frequency disinfection routines.

Ensuring the safety of the people on the frontlines is also important. Cleaning staff tasked with sanitising hospital bathrooms are particularly vulnerable to exposure from toilet plume droplets. It is imperative that workers receive specialised training and are equipped with personal protective equipment and procedural updates tailored to this emerging threat.

The C. difficile toilet flushing study emphasises that hygiene practices in hospital restrooms are due for a major rethink. Protecting patients and staff alike will require a renewed focus on engineering controls, behavioural interventions and above all, a commitment to meticulous science-driven cleaning standards.