Water Safety Design Reviews: Today’s Build, Tomorrow’s Risk

Water safety should no longer be a background consideration in healthcare, education and public-sector construction. It is known to be one of the most common causes of delayed building openings, extended commissioning periods and costly remediation work. 

For NHS estates teams, private healthcare providers, developers, facilities managers, local authorities and education estates, water safety must be treated as a critical part of design and project governance, not an afterthought. 

Water Safety for New Builds and Refurbishments

Across the UK, new builds and refurbishments have faced major disruption because water systems were not designed, installed or commissioned safely. These delays are not caused by water suppliers or external treatment works, but by issues within the building itself, such as poor sequencing, with stagnation, contamination being introduced during construction, or design choices that clash with clinical requirements.

There is a perception amongst both contractors and their clients that handover should go ahead based on two certificates, namely a disinfection certificate and a laboratory testing certificate (relating to one or more samples taken by the disinfection contractor on the same day the disinfectant is neutralised/flushed from the system). This leads to the misconception that “anything goes during construction because chlorine will magically deal with it at the end”. Until this perception is changed, delays, costs, deaths and criminal prosecutions will persist.

When Water Safety Goes Wrong: Real-World Delays

Several high-profile UK projects have experienced opening delays directly attributable to water safety failures. These examples highlight how a single misjudgement or oversight can ripple into major financial and, more importantly, operational consequences.

Some examples referenced did not prevent initial building occupation but are included to demonstrate how water safety risks introduced during design, construction or commissioning can emerge shortly after opening, resulting in service disruption, remediation works and significant operational impact.

Belfast Maternity Hospital:
contamination found during commissioning
During final preparations to open the new maternity building at the Royal Victoria Hospital, testing identified contamination with Pseudomonas aeruginosa at multiple outlets. This pathogen carries serious risks for neonates; thus, opening could not proceed. The domestic water system has and is undergoing extensive works, including disinfection works, remediation and re-testing, delaying the launch of a facility that was otherwise physically complete.

This case underscores how contamination introduced during construction or stagnation in underused pipework can stop a critical facility from becoming operational.

Worthing Integrated Care Centre:
Legionella discovery halts occupation
In Worthing, final water tests revealed the presence of Legionella in the domestic system. Again, as with Belfast, the building was ready for use, but the discovery forced a halt to occupation. Mitigation and retesting introduced delays and additional costs (the original budget for the project of just under £34m has risen to circa £45m by March 2025), causing avoidable setbacks, which are reported to have originated from installation and commissioning issues inside the building.

Queen Elizabeth University Hospital, Glasgow:
Early fill creates long-term risk
At the Scottish Hospitals Inquiry, evidence showed parts of the system had been filled for over a year before occupation. This created ideal conditions for stagnation and biofilm growth, which in turn complicated commissioning and contributed to ongoing water-quality challenges once the hospital opened.

Royal Papworth Hospital, Cambridge:
Post-opening water system infection outbreak
At the Royal Papworth Hospital on the Cambridge Biomedical Campus, a Mycobacterium abscessus outbreak was linked to the hospital’s water system in the months following its May 2019 opening, with several patients infected, with reports of at least two later dying from complications associated with the pathogen.

Coroner findings and Prevention of Future Deaths reports noted gaps in how certain waterborne bacteria are addressed in healthcare water safety guidance, prompting ongoing mitigation, sampling and governance improvements. This example highlights that even after opening, complex healthcare water systems can present significant infection risks if not controlled through robust multidisciplinary water safety planning and oversight.

Why Certain Sectors Face Higher Risk

Healthcare, education and public-sector projects bring together conditions that elevate water safety risks:

• Complex, multi-level plumbing systems
  
  
• Intermittent or phased occupancy
  
  
• Clinical and infection-control requirements
  
  
• Challenging refurbishment conditions in ageing estates
  
  
• Programme pressures that compress commissioning
  
  
• Large numbers of outlets and specialist fixtures.

With these factors at play, even minor design variations or installation errors, such as unplanned dead legs, temperature instability, system balancing, poorly chosen outlets or extended stagnation via wetted systems, can derail handover.

This is why water safety cannot simply be verified at the end; it must be engineered in from the beginning.

Authorising Engineer (Water): The Independent Safety Voice

An Authorising Engineer (Water) (AE(W)) plays a vital role in protecting a project’s programme, cost and safety outcomes. Their independence from designers and contractors allows them to challenge assumptions and decisions that could introduce future risk, the AE(W):

• Reviews early-stage designs to ensure compliance with HTM:04-01, Water Safety Plans and other pertinent national guidance documentation
  
  
• Prevents inappropriate material substitutions or changes introduced through value engineering
  
  
• Advises on materials, outlet selection, routing and system configuration
  
  
• Prevents premature filling and prolonged stagnation
  
  
• Oversees / witnesses installation activities, flushing, disinfection and correct commissioning
  
  
• Provides assurance for readiness-to-open and handover.

The AE(W)'s independence is crucial; their role prioritises safety, not programme pressure, allowing them to challenge decisions that could introduce long-term risk.

The Project Water Safety Group: Multi-Disciplinary Assurance That Works

A Project Water Safety Group (PWSG) ensures that every key discipline is involved from the design stage to occupation. This typically includes the AE(W), estates team,   Authorised Person (Water), designers, contractors, infection prevention professionals, FM teams, commissioning managers and project managers.

When functioning well, the PWSG:

• Aligns design intent with clinical and operational needs
  
  
• Ensure that outlet placement, tap type and pipe routing suit real-world use
  
  
• Estates teams can highlight operational realities, maintenance access and compatibility with existing systems
  
  
• Coordinates sequencing so systems are not filled too early
  
  
• Maintains flushing and water quality oversight during construction
  
  
• Prevents commissioning from being rushed or compromised, thus contractors and commissioning teams can align construction sequencing with safe water practices
  
  
• Ensures a fully verified, safe water system at handover.

Without a strong PWSG, risks slip through the cracks — only to surface during pre-occupation testing, when the options are limited, expensive and disruptive.

Without this collective approach, risk multiplies. This is when pipework is installed in suboptimal routes, temporary dead legs remain unnoticed, flushing is inconsistent, or systems sit stagnant for months before being tested. These only come to the surface during pre-occupation testing, when the options are limited, expensive and disruptive.

The Cost of Late Discovery - Why Early Engagement Matters

The most significant water safety delays occur when problems designed in at RIBA Stages 2–3 are only discovered at commissioning. By then, pipework is sealed behind finished walls, ceiling voids are closed, and the cost of remediation is exponentially higher.

Early AE(W) and PWSG involvement enables:

• Risk removal rather than risk management
  
  
• Correct specification of materials, valves, outlets and routing
  
  
• Alignment between design intent and infection prevention
  
  
• Sequencing that prevents premature filling or stagnation
  
  
• Safe, efficient commissioning
  
  
• A complete, accurate water safety file ready at handover.

A New Standard for Safe Openings

Water safety design reviews are no longer optional in healthcare and public sector developments. They are essential elements of project governance and a critical assurance mechanism for estates teams, FM providers, Trust boards, local authorities and education leaders.

Buildings are becoming more complex, pressures on programme and budget are increasing, thus the consequences of getting water safety wrong are now clearer than ever.

By embedding a qualified AE(W) and empowering a multidisciplinary Project Water Safety Group, organisations ensure:

• Early-stage design reviews
  
  
• Clear governance through a PWSG
  
  
• Competent, independent AE(W) oversight
  
  
• Strong sequencing controls
  
  
• Robust commissioning and verification
  
  
• A complete, accurate Water Safety File at handover
  
  
• Facilities open safely
  
  
• Occupation is not delayed by preventable water issues
  
  
• Vulnerable users are protected from avoidable risk
  
  
• Assets are compliant from day one
  
  
• Long-term operational and infection control performance is safeguarded.

Water safety must be viewed not as a specialist add-on (built in, not bolted on), but as a core design discipline, one that underpins the safety, resilience and readiness of every new healthcare, education and public-sector building.

Embedding a qualified AE(W) and a well-structured PWSG is the most effective way to prevent the kinds of delays and disruptions now seen too frequently across the UK.

Feel free to reach out if you have any questions about the issues mentioned above or if you would like to consult with one of our experts on water hygiene.

Editor's Note: The information provided in this blog is correct as of the date of original publication - March 2026.

© Water Hygiene Centre 2026