WATER SAFETY
All sampled locations were previously positive as discussed above, therefore demonstrating a complete reduction from 100% to 0% over the three month study.
Monochloramine residuals were again seen to gradually increase within the system as the disinfectant took control. (See Figures 1 and 2). As outlined above, average residual
monochloramine concentrations increased during the study period, and stabilised between 1.5 and 3.0 mg/L, with consistent readings across distal outlets. Data indicated an inverse relationship between L. pneumophila detection and monochloramine residuals, suggesting effective biofilm penetration and persistence of the disinfectant throughout the water systems. The introduction of monochloramine delivered several operational advantages: n Elimination of routine local disinfections, resulting in significant timesaving for the site estates teams.
n Significant reduction in point-of-use filter
replacements, lowering consumable costs. Those locations where Legionella has not been detected for 3 consecutive events are no longer fitted with filters.
n Cessation of daily manual flushing at previously positive outlets, once again resulting in considerable time saving. Any little used outlets are now being flushed twice a week only, or in accordance with the WSP.
n Hospital estates teams have reported fewer reactive maintenance interventions.
n A corresponding reduction is Pseudomonas aeruginosa contamination (the study for this is still ongoing).
These findings align with international evidence demonstrating that monochloramine not only suppresses Legionella but also reduces colonisation by other opportunistic pathogens such as non-tuberculosis mycobacterium (NTMs) and Pseudomonas spp. Monochloramine’s lower reactivity with organic matter compared to free chlorine allowed it to persist for longer within the distribution systems, maintaining effective residuals at distal outlets. Residual levels throughout this trial remained within safe limits, with no reports of taste, odour, or aesthetic concerns from users. The Sanikill Lite generator operated reliably throughout
the evaluation, requiring only periodic replenishment of precursor chemicals and standard dosing pump calibration checks. This low-maintenance profile contrasts with more labour-intensive control methods such as regular thermal disinfections or manual disinfection, both of which can pose scalding or handling risks. The study duration (three months) represents a limitation, as long-term stability and recontamination potential were not evaluated beyond this period. However, these short-term results are consistent with multi-year international case studies demonstrating sustained control with monochloramine systems in healthcare environments. Future studies incorporating six- and twelve- month datasets will strengthen confidence in long-term performance and resilience.
Conclusions Monochloramine dosing achieved complete eradication of L. pneumophila within three months across these two complex oncology hospital water systems with a persistent history of contamination. Key outcomes include:
n 100% reduction in L. pneumophila-positive outlets within the 12 weeks period.
n Stable monochloramine residuals maintained between 1.5–3.0 mg/L.
n Secondary reduction in Pseudomonas aeruginosa detections (study ongoing).
n Reduced operational workload and maintenance demand.
The Sanikill monochloramine system provided a practical, reliable, and scalable approach to water safety management. Its integration into healthcare water systems offers a sustainable and resource-efficient alternative to traditional control measures, enhancing patient safety and reducing infection risk across critical care environments.
Further reading n NHS Estates. Technical Bulletin: Control of Nontuberculous
Mycobacteria and Other Opportunistic Pathogens in Healthcare Water Systems. NHS England; 2024.
n World Health Organization. Guidelines for Drinking-Water Quality. 4th ed. WHO; 2023.
n Kool JL, et al. Hospital-acquired Legionnaires’ disease linked to potable water. Infect Control Hosp Epidemiol. 2000.
n Farina C, et al. Water Safety Plan, Monochloramine Disinfection and Extensive Environmental Sampling Effectively Control Legionella and Other Waterborne Pathogens in Nosocomial Settings: The Ten-Year Experience of an Italian Hospital. Microorganisms. 2023;11(7):1794.
n Lin YE, et al. The efficacy of monochloramine for controlling Legionella in hospital water systems. Am J Infect Control. 2011.
n Bartram J, Chartier Y. Legionella and the Prevention of Legionellosis. WHO Press; 2019.
Sanikill Lite installed at hospital in London.
Harijeet Singh
Harijeet Singh BSc is a Business Development manager at Goodwater with over 10 years’ experience in the water treatment industry. His work has primarily focused on microbiological control in both new and existing water systems. With a background in microbiological sciences and practical experience supporting engineering teams, he looks to bridge the gap between design and infection control through data-driven, pragmatic approaches that enhance hospital water safety. Both Harijeet and
Vikram focus on providing practical solutions, innovation, and collaborate closely with both public health and mechanical engineers, helping them navigate complex water treatment challenges and to design compliant water treatment systems for various industries. They also work alongside infection prevention specialists and NHS water safety groups to develop evidence-based strategies for microbial control in hospital water systems.
January 2026 Health Estate Journal 57
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