Hybrid work schedules + unused taps = the perfect breeding ground for bacteria. 

The modern workplace is evolving. Where once office buildings hummed with activity five days a week, now many sit partially empty as hybrid working becomes the new normal. The marketing team might be in on Mondays and Thursdays, the finance department on Tuesdays and Wednesdays and those meeting rooms on the third floor? They’re lucky to used once a fortnight. 

Great for work-life balance. Not so great for your water systems. 

At HCS Water Treatment, part of Premier Technical Services Group Ltd (PTSG), we’ve observed a concerning trend: workplace water systems designed for consistent, daily use now operating in buildings with unpredictable, partial occupancy. The result? A perfect petri dish for Legionella bacteria. 

The New Workplace Reality: A Water Safety Perfect Storm 

The post-pandemic workplace has created unprecedented water safety challenges: 

1. The Hybrid Working Revolution 

Current workplace usage patterns are fundamentally different: 

• Offices operating at 30-60% capacity on any given day 

• Entire floors or sections used sporadically 

• Buildings fully occupied only for specific events or meetings 

• More workers hot-desking rather than using fixed locations 

• Some areas effectively abandoned as space needs change 

Each of these patterns creates opportunities for water to stagnate in pipes, outlets and systems giving Legionella bacteria the ideal conditions to multiply. 

2. The Infrastructure Mismatch 

Most office buildings were designed with assumptions that no longer hold true: 

• Water systems sized for full daily occupancy 

• Plumbing designed for consistent, not intermittent, use 

• Tank capacity calculated based on pre-hybrid working patterns 

• Circulation systems that depend on regular usage 

• Maintenance schedules built around predictable usage patterns 

This disconnect between design and actual usage creates systemic vulnerabilities. 

3. The Overlooked Areas 

Every workplace has them the spots where water might sit undisturbed for days or weeks: 

• Executive bathroom in the rarely used corner office 

• Shower facilities installed for cycling commuters but used by only a handful of staff 

• Kitchenettes on floors now used primarily for storage 

• Backup water heaters that kick in only during peak demand 

• Sinks in meeting rooms that see occasional use 

These forgotten corners of your water system can become incubators for bacterial growth. 

4. The Operational Blindspots 

New working patterns have created gaps in water safety management: 

• Reduced facilities staff making fewer observation rounds 

• Unclear responsibility for flushing rarely used outlets 

• Temperature monitoring that doesn’t account for usage patterns 

• Maintenance access challenges when areas are occupied unpredictably 

• Documentation systems not adapted to variable occupancy 

The Science: Why Hybrid Working Creates Legionella Risk 

The connection between hybrid working and increased Legionella risk isn’t just speculation it’s rooted in microbiology: 

Stagnation: Bacteria’s Best Friend 

When water sits undisturbed in pipes, several things happen: 

1. Disinfectant levels decline as chlorine dissipates 

2. Biofilm develops on pipe surfaces, providing a protective environment for bacteria 

3. Sediment accumulates, providing nutrients for microorganisms 

4. Water temperature equalises with ambient surroundings, potentially reaching the 20-45°C danger zone 

Legionella bacteria thrive in these conditions, potentially doubling their population every 4-6 hours in optimal circumstances. 

Temperature Drift in Underused Systems 

In partially occupied buildings: 

• Hot water systems may cool to dangerous temperatures in rarely used branches 

• Cold water pipes running through warm ceiling voids can heat up to the Legionella growth range 

• Mixing valve accuracy may drift without regular use 

• Thermal stratification can occur in storage tanks with reduced demand 

The Aerosolisation Risk 

When taps and showers are finally used after periods of inactivity: 

• Biofilm chunks may break loose 

• Higher bacterial concentrations are present in the initial water flow 

• Aerosols are generated that can be inhaled by users 

This creates a particularly high-risk moment for Legionella exposure. 

When Office Water Goes Wrong 

The consequences of inadequate water management in modern workplaces are not theoretical. Consider these real examples: 

The Multi-Tenanted Office Block Case 

A large office building with multiple corporate tenants implemented a hybrid working policy across all businesses. Within months, water samples showed alarming Legionella counts in several areas. Investigation revealed: 

• No coordination between tenants on building occupancy patterns 

• Entire sections sitting unused for days at a time 

• No clear responsibility for managing shared water facilities 

• Temperature monitoring continuing on the pre-pandemic schedule without accounting for new usage patterns 

While caught before causing illness, the building required complete system disinfection and a fundamental rethink of its water management strategy. 

The Tech Company Cluster 

A technology company occupying three floors implemented a strict two-day-per-week office schedule. Three employees reported respiratory symptoms after returning to on-site work. Testing confirmed Legionella in the showers installed for bicycle commuters. The investigation found: 

• Shower facilities used by fewer than 10% of the staff who once used them 

• No flushing programme implemented for underused outlets 

• Temperature control issues in the hot water system serving the shower area 

• No risk assessment review following the shift to hybrid working 

The company faced not only health consequences for affected staff but also potential liability issues and significant remediation costs. 

The Flexible Workspace Provider 

A company offering flexible office space saw dramatically shifting usage patterns as client businesses adopted hybrid models. Water quality issues emerged across multiple sites. Root causes included: 

• Inability to predict which areas would be used from day to day 

• Water systems designed for full occupancy operating at partial capacity 

• Confusion over responsibility for water safety between the provider and client businesses 

• Inadequate monitoring of changing usage patterns 

The Legal Landscape: Your Responsibilities Haven’t Changed 

While working patterns have evolved dramatically, legal obligations regarding water safety remain as stringent as ever: 

Health and Safety at Work Act 1974: Employers and building managers retain the fundamental duty of care to employees and visitors, regardless of how often they’re physically present. 

Control of Substances Hazardous to Health (COSHH) Regulations 2002: The requirement to control Legionella risk applies equally to buildings used five days a week or one day a week. 

L8 Approved Code of Practice: This guidance explicitly addresses the risks of underused outlets and systems issues now much more common in hybrid workplaces. 

HSG274 Technical Guidance: Part 2 provides detailed guidance on managing hot and cold water systems, with specific attention to usage patterns and stagnation risks. 

Landlord/Tenant Responsibilities 

In multi-occupied buildings, responsibilities must be clearly defined between building owners, managing agents, and tenants a particularly important consideration as usage patterns become more complex. 

The Critical Control Points: Managing Water Safety in the Hybrid Workplace 

Effective Legionella control in modern workplaces requires adaptations to address new usage patterns: 

1. Usage Pattern Mapping 

Understanding how your building is actually used is the essential first step: 

• Document which areas are used on which days 

• Identify outlets that may sit unused for extended periods 

• Track seasonal variations in occupancy 

• Monitor how usage patterns evolve over time 

• Consider technology solutions for occupancy tracking 

2. Adaptive Flushing Programmes 

Develop flushing protocols that reflect actual building usage: 

• Implement sentinel point flushing regardless of occupancy 

• Create clear responsibility allocations for flushing tasks 

• Consider automatic flushing systems for high-risk or rarely accessed areas 

• Document all flushing activities with specific attention to little-used outlets 

• Align flushing schedules with known occupancy patterns 

3. Enhanced Monitoring Approaches 

Standard monitoring may be insufficient for hybrid workplaces: 

• Increase temperature monitoring frequency at key risk points 

• Consider remote monitoring technology to reduce resource requirements 

• Implement additional microbiological sampling in high-risk areas 

• Monitor disinfectant levels where water stagnation is likely 

• Track patterns and trends to identify emerging issues 

4. System Modifications 

In some cases, physical changes to water systems may be appropriate: 

• Consider removing or disconnecting truly redundant outlets 

• Install point-of-use water heaters in areas with irregular use 

• Implement automatic flushing devices on key outlets 

• Reconfigure circulation systems to reduce dead legs 

• Resize storage capacity to match actual usage 

5. Clear Communication Protocols 

With more complex occupancy patterns, communication becomes critical: 

• Ensure all stakeholders understand their water safety responsibilities 

• Develop simple guidance for non-technical staff 

• Implement reporting mechanisms for water quality concerns 

• Maintain open channels between facilities teams and department managers 

• Create clear escalation protocols for water safety issues 

The HCS Approach to Modern Workplace Water Safety 

At HCS Water Treatment, we’ve evolved our approach to address the unique challenges of water safety in hybrid working environments. We understand both the technical requirements and the practical operational constraints facing modern workplaces. 

Our workplace water safety programme combines: 

1. Occupancy-Adaptive Risk Assessment 

We conduct detailed risk assessments specifically designed for variable occupancy buildings: 

• Analysis of actual vs. designed usage patterns 

• Identification of high-risk stagnation points 

• Evaluation of monitoring programme suitability 

• Assessment of management system adaptability 

• Recommendations tailored to hybrid working environments 

2. Technology-Enhanced Management 

We leverage technology to address the challenges of variable occupancy: 

• Remote temperature monitoring solutions 

• Digital flushing record systems 

• Occupancy-linked risk visualisation 

• Automated compliance reporting 

• ZetaSafe Dashboard for real-time compliance visibility 

3. Resource-Optimised Implementation 

We recognise the resource constraints many facilities teams face: 

• Efficient monitoring protocols focused on highest-risk areas 

• Practical flushing programmes that acknowledge staffing realities 

• Clear prioritisation guidance when resources are limited 

• Automation recommendations where appropriate 

• Simple documentation systems that minimise administrative burden 

4. Stakeholder Engagement 

We involve the wider organisation in water safety: 

• Role-specific guidance for facilities, HR, and departmental managers 

• Employee awareness materials regarding water safety 

• Training programmes adapted for partial-presence staff 

• Practical tools for non-technical personnel 

• Clear communication of responsibilities and expectations 

5. Continuous Adaptation Support 

We recognise that workplace patterns continue to evolve: 

• Regular review of risk assessments as usage changes 

• Guidance on monitoring and responding to emerging patterns 

• Support during workplace reconfiguration projects 

• Advice on water safety implications of occupancy decisions 

• Ongoing consulting as your workplace continues to transform 

Future-Proofing Your Workplace Water 

If you’re responsible for an office or workplace that’s adopted hybrid working, here are essential actions to take now: 

1. Review and Update Your Risk Assessment 

• Ensure it reflects actual current usage patterns, not pre-pandemic assumptions 

• Identify areas with significantly reduced use 

• Document new high-risk points created by hybrid working 

• Evaluate whether control measures remain appropriate 

• Consider engaging specialists with experience in variable-occupancy buildings 

2. Implement Occupancy-Based Monitoring 

• Adapt temperature monitoring schedules to reflect usage patterns 

• Increase frequency at high-risk sentinel points 

• Consider microbiological sampling in areas of concern 

• Document actual usage alongside monitoring results 

• Review and analyse for patterns and trends 

3. Develop a Hybrid-Specific Flushing Programme 

• Create clear protocols for flushing rarely used outlets 

• Assign specific responsibilities that account for staff presence patterns 

• Create simple record-keeping systems 

• Consider technology solutions for verification 

• Ensure coverage during all-remote periods 

4. Communicate Clearly 

• Ensure facilities teams understand changed risk profiles 

• Brief departmental managers on their responsibilities 

• Provide guidance to all staff on water safety awareness 

• Establish clear reporting channels for concerns 

• Create visual reminders in key areas 

5. Plan for Further Evolution 

• Establish processes to capture further changes in workplace usage 

• Create triggers for risk assessment reviews 

• Consider workplace design changes that might reduce water system risks 

• Evaluate technology solutions that could improve management 

• Maintain flexibility in water safety programmes 

Hybrid Working Requires Hybrid Thinking 

The shift to hybrid working represents one of the most significant changes to workplace operations in generations. Yet many organisations continue to manage their water systems as if nothing has changed. 

This disconnect creates risk. Water systems designed for full, consistent occupancy are now operating in buildings that may sit partially empty for days at a time. Without appropriate adaptation of management approaches, these conditions can transform ordinary office water systems into potential health hazards. 

The good news is that with proper risk assessment, monitoring, and management, these risks can be effectively controlled. The key is recognising that your water safety approach needs to evolve alongside your workplace strategy. 

Is your workplace water management still stuck in the pre-hybrid era? Contact HCS Water Treatment today on 0141 212 7247 or email us at hello@hcsuk.org to discuss how our workplace-focused water safety services can help you address the unique challenges of modern, flexible working environments. Because your water system doesn’t know you’ve gone hybrid unless you tell it.