Précis of NHS Estates Technical Bulletin 2024/3

Introduction

The NHS Estates Technical Bulletin 2024/3 (NETB 2024/3) was issued in response to increasing concerns about outbreaks of Mycobacterium abscessus, a nontuberculous mycobacterium (NTM), in newly constructed hospital environments, particularly within a lung transplant unit. These outbreaks have prompted urgent action to revise the application of HTM: 04-01 (2016), particularly in how new builds and refurbishments are managed in relation to water safety for high-risk patient groups.

Drinking water, although compliant with regulatory microbiological standards, still contains opportunistic pathogens such as Legionella, Pseudomonas aeruginosa, and NTM, which are typically harmless to healthy individuals but can cause life-threatening infections in immunocompromised patients.

Objectives and Scope

This bulletin is applicable across all NHS healthcare settings and aims to:

• Enhance HTM: 04-01 with specific provisions for managing NTM and other waterborne pathogens.
• Specify additional measures required in new constructions and refurbishments for spaces used by immunocompromised patients.

It is designed not as a replacement of HTM: 04-01, but as a supplementary framework that mandates a proactive and precautionary approach, especially where scientific certainty is incomplete.

At-Risk Patient Groups

High-risk groups include:

• Lung transplant recipients
• Cystic fibrosis (CF) patients
• Haematology/oncology patients undergoing neutropenic chemotherapy
• Solid organ transplant patients’ post-intensive treatment
• Allogeneic stem cell transplant recipients
• Patients with central venous access lines

For these groups, pulmonary, bloodstream, skin, and lymphatic infections are of primary concern. Consequently, protection measures must be stringent and tailored to the level of immunosuppression.

Governance and Oversight

A core tenet of the bulletin is that safety governance must be embedded from inception. The following principles apply:

• Board Accountability: The Trust Board must appoint a competent Executive Director/Senior Responsible Owner (SRO) with responsibility for patient safety in water system design and construction.
• Project Water Safety Group (PWSG): A multidisciplinary PWSG must be formally established to:
  • Develop a Project Water Safety Plan (PWSP)
  • Oversee design, procurement, commissioning, and ongoing safety validation
  • Ensure designs align with BS 8680 and BS 8580 risk assessment protocols

The PWSG should include experts in infection prevention and control (IPC), clinical representatives, microbiologists, engineers, and estates personnel.

Key Recommendations

Infection Control and Water System Specifications

Due to the resistance of NTM to heat and biocides, reliance on water treatment alone is not sufficient. Instead, the system should:

• Minimise stagnation and use components resistant to microbial colonisation
• Avoid materials such as plastics that promote biofilm formation
• Be constructed with unused, pre-certified fittings only
• Undergo filling and commissioning as close to handover as possible, post-fit-out
• Strict hygiene control is required during installation to prevent nutrient ingress and contamination from environmental factors such as humidity or rodents.

Project Water Safety Plan (PWSP)

The PWSP is the overarching strategy for ensuring the safe delivery of water throughout a project’s life cycle. It must:

• Define governance, roles, responsibilities, and escalation procedures
• Set validation criteria, sampling plans, and thresholds for microbiological and chemical safety
• Address all potential waterborne transmission routes, including ingestion, inhalation, aspiration, and dermal contact

Protection Measures by Immunosuppression Level

Appendix 3 defines four protection levels and their respective control measures:

• Level I (Mild): Avoid uncontrolled sources of water
• Level II (Moderate): Requires antimicrobial barriers and control of bathroom bacterial reservoirs
• Level III (Severe): Use filtered or low-bacterial-count water; limit or avoid showers unless controlled
• Level IV (Extreme): Only sterile water for drinking, hygiene, and washing

These measures must be integrated into both daily operations and building design.

Gaps in Knowledge and Laboratory Limitations

Several knowledge deficits challenge implementation. Thus, the guidance advocates a precautionary approach, assuming risk unless proven otherwise.

• Unclear exposure thresholds for NTM infections
• Variability in species-specific virulence
• Lack of standardised detection methods across laboratories complicates risk interpretation

Implementation, Monitoring, and Compliance

Implementation will be monitored through the NHS Premises Assurance Model. Project assurance sampling post-commissioning is mandatory. All stakeholders must be trained and consulted throughout to ensure a consistent understanding of safety requirements.

Every change in project design or materials must undergo a documented risk review. There is a strong emphasis on fostering a no-blame culture where near misses are openly shared and translated into learning opportunities.

Conclusion

NETB 2024/3 reinforces that “compliance is not safety.” For patients at high risk of waterborne infections, particularly those exposed to NTM, the healthcare estate must be designed and managed with patient safety as its primary objective. This requires more than adherence to guidelines: it demands proactive risk governance, cross-disciplinary collaboration, and meticulous design, construction, and operation practices.

By adopting a life cycle approach, engaging all stakeholders early, and applying multi-barrier infection control strategies, NHS organisations can ensure that the built environment supports, rather than endangers, the delivery of safe and effective care to those most vulnerable.