Biofilms, drains, and the hidden risks in healthcare environments: disinfection strategies

At Infection Prevention and Control 2026 in Birmingham today, I was delighted to present alongside Dr Phil Norville on the role of drains and biofilms as reservoirs for healthcare‑associated infection, and how we might better approach their control.

The session, hosted by IPC Partners in partnership with Tristel, combined emerging scientific evidence with live audience polling. This allowed us to discuss what the literature currently tells, and also to explore how IPC professionals across the UK are thinking about drains, the risks they pose, and the strategies being used to manage them. The session followed on from excellent talks by Dr Mark Garvey on the sink splash zone and Prof Jean-Yves Maillard on biofilms and disinfection. In a way, these sessions presented the problem, and we were more focussed on discussion solutions (although…plot spoiler…there isn’t a one-size-fits-all solution here!).

Why drains have stayed out of sight and out of mind

Historically, drains have occupied a bit of a gap between IPC, estates, and clinical teams. They are rarely visible, difficult to sample meaningfully, and often excluded from routine cleaning and disinfection frameworks. Yet evidence increasingly suggests that this blind spot matters.

Healthcare drains provide ideal conditions for microbial persistence. They are wet, nutrient rich, and complex in their internal structure. Over time, they can become colonised with multispecies biofilms, including organisms of clinical concern. Several outbreak investigations now point towards drains as persistent reservoirs, sometimes prolonging outbreaks for years and frustrating conventional control measures.

Biofilms bend the rules

A central theme of the session was that biofilms challenge and ought to change the way we think about disinfection. Organisms embedded within biofilms behave very differently from planktonic bacteria tested in standard efficacy assays. Reduced susceptibility – sometimes by 10 or more orders of magnitude – is common, and this is not explained by traditional resistance mechanisms alone.

Biofilm‑specific features such as extracellular polymeric substances (EPS), metabolic heterogeneity and persister cells all reduce the impact of antimicrobial agents. In practical terms, this means that disinfection approaches that are effective in the laboratory, and especially in suspension testing, may perform very differently once deployed in real drains under real‑world conditions.

Transmission pathways: beyond the drain itself

One aspect that consistently resonates with clinical teams is the concept of the sink splash zone. Evidence demonstrates aerosolisation and splash‑back from drains can contaminate surrounding areas and equipment, including intravenous devices, respiratory equipment and personal care items. This means that drains are an active interface between the environment and patient care, rather than a purely engineering problem.

What the audience told us: Mentimeter insights

Live polling during the session provided a valuable snapshot of current IPC thinking around drains and disinfection.

• When asked to rank common transmission risks for healthcare‑associated infection, hands were unsurprisingly ranked highest. What was more striking was that drains were ranked second, above shared medical equipment and endoscopes. This suggests that awareness of environmental reservoirs has matured considerably in recent years.
• When the audience was asked more directly whether drains are an important reservoir for transmission in healthcare, on a five‑point scale from strongly disagree to strongly agree, the average response was 4.6, indicating strong consensus that drains matter.
• However, when it came to how organisations are managing this risk, responses were far more heterogeneous. Chemical approaches were the most commonly reported strategy, often used in combination with other measures. Relatively few respondents reported regular use of thermal approaches or physical removal of drains, and a notable proportion indicated that no specific drain strategy was in place at all. This variation highlights both the operational challenges and the lack of clear, standardised guidance.
• Finally, when asked what matters most in a disinfectant designed for drains and biofilms, efficacy emerged as the top priority, followed by safety, residual activity and material compatibility. This reinforces the reality that IPC teams are looking for solutions that work in practice, not just in theory, but cannot ignore safety or practicality.

Approaches to drain disinfection: no single answer

We discussed thermal, chemical and physical approaches to drain management, each of which carries advantages and limitations. Thermal flushing and steam can disrupt biofilms but are not always feasible or safe. Physical removal may be effective but is disruptive, costly and rarely sustainable. Chemical approaches are the most widely used, yet their effectiveness is highly dependent on formulation, delivery, contact time and the presence of organic matter. Oxidising chemistries, such as chlorine dioxide and peracetic acid offer the most attractive options for addressing drain contamination in a healthcare setting.

The testing gap – and the need for innovation

One of the most important conclusions from both the evidence and the discussion is that traditional disinfectant testing does not adequately reflect drains. Endpoints based on planktonic bacteria tell us little about performance against mature biofilms in complex pipework. If we are serious about tackling drain‑associated risk, we need testing frameworks that better reflect real‑world use: biofilm‑specific measures, models that incorporate realistic geometry and organic load, and independent validation.

Looking ahead

As new hospitals are built and existing estates refurbished, there is an opportunity to embed drain risk into design decisions rather than retrofitting solutions after problems emerge. The alignment between emerging evidence and audience perception at IPC 2026 around drains and disinfection was striking. This is an issue that frontline practitioners are fully aware of and beginning to address. Drains may be out of sight, but their impact on infection risk no longer should be.