Achieving Significant Legionella Reduction Through Copper–Silver Ionisation For Southern Hospital

Background

A large southern hospital collaborated with Marlowe Environmental Services to implement the BifiPro II Copper & Silver Ionisation Unit, aimed at eradicating Legionella within one of its buildings.

Installed in February 2025, the system has demonstrated outstanding efficacy through a comprehensive sampling programme, achieving a significant reduction in Legionella positivity and enabling the removal of multiple point-of-use filters.

The Challenge

Over time, multiple projects and pipework modifications had resulted in both known and unknown dead legs being left within the system.

Changes in building usage also meant that previously high-use areas had become low-use zones. These factors, combined with persistent airlocks and disrupted flow dynamics across the complex water network, contributed to significant biofilm accumulation and elevated Legionella levels throughout the building.

As a result, point-of-use (POU) filters were installed extensively, costing the Trust thousands of pounds annually.

Our Solutions

A BifiPro II was installed to the water system after the softener to allow CuAg Ions to be dosed to the water system.

An extensive sampling programme was put into place to track the results and this indicated where POUs could be removed following the guidelines of the Trust’s Water Safety Policy.

The graph below shows the dropping positivity rates following the BifiPro II installation. The expected peak around May was indicative of the shearing of biofilm within the water system. Positivity then started to drop as seen below:

Results & Outcomes

Current filter count and savings:

• June spend on 31-day filters: £ 3080pm
• Oct spend on 31-day filters: £ 880pm (Annualised saving £26,400)
• Sampling ongoing for remaining areas – projected spend on 31-day filters @ 90% reduction: £ 302.50pm (Annualised saving £33,300)

Overall, the results show that the BifiPro II has delivered a strong, stable improvement in water safety performance. The system has addressed longstanding microbiological challenges, reduced reliance on costly interim controls, and provided the large southern hospital with a more resilient and sustainable water management solution.