Preventing and Removing Pseudomonas in Closed-Water Systems

Pseudomonas bacteria, commonly found in closed-circuit water systems, have become a widespread problem across the UK. If left unchecked, these bacteria can compromise the safety and efficiency of pipework and HVAC systems, leading to significant operational and financial challenges.

While Pseudomonas can pose health risks in some settings, in closed-water systems, human exposure is minimal. The real issue lies in the damage caused to heating, cooling, and ventilation equipment. Preventing Pseudomonas requires careful system design, thorough pre-commissioning cleaning, and ongoing maintenance tailored to the specific needs of the system.

Understanding Pseudomonas and It’s Impact

What is Pseudomonas?

Pseudomonas is a type of bacteria that thrives in water, particularly in stagnant or slow-flowing conditions. The most problematic species for water systems is Pseudomonas aeruginosa, which can cause serious infections in immunosuppressed patients within healthcare environments. This is not a risk factor for closed systems, however.

Why is Pseudomonas a Problem?

Pseudomonas can wreak havoc on water systems, particularly in modern buildings with small-bore pipework and narrow valve orifices. Key issues include:

• Biofilm formation: Pseudomonas promotes the growth of biofilm, a slimy microbial layer that clogs pipes, reduces efficiency, and harbours other harmful bacteria.
• Corrosion: The bacteria encourage the rise of Sulphate Reducing Bacteria (SRBs), which convert sulphates in water into sulphides. This process causes localised pitting and perforation in metal pipes.
• System downtime: Inefficiency, leaks, and equipment damage lead to increased downtime, repair costs, and energy consumption.

Preventing Pseudomonas in Water Systems

Stopping Pseudomonas before it takes hold begins with smart system design, rigorous cleaning, and continuous monitoring. Here’s how:

1. Optimise system design

• Avoid design flaws like dead legs or capped pipes where water can stagnate. If such features are unavoidable, ensure they are looped out and regularly circulated.
• Ensure adequate flow throughout the system to prevent low-flow areas where bacteria can thrive.

2. Pre-commissioning cleaning

• Follow BSRIA guidelines for pre-commissioning cleaning to ensure systems are free from contaminants before operation.
• Use chemical flushing to remove debris, grease, and microbial growth. However, remediation cleaning after contamination can never fully restore the system to its original state, making pre-commissioning critical.
• Use real-time monitoring throughout the pre-commissioning cleaning and handover process, to check for conditions that can be indicative of bacterial proliferation and subsequent corrosion, such as elevated dissolved oxygen levels, pressure, temperature and pH changes.

3. Ongoing water treatment

• Use real-time monitoring to identify issues before major damage occurs. 24/7 remote condition monitoring can lead to improved maintenance practices, and reduced flushing, significantly cutting the risk of repairs, breakdown and downtime.
• Implement a closed water system sampling regime to monitor bacterial levels. Biocide dosing may be required at times, but this should be done with caution to avoid creating other issues in the system such as corrosion.

Managing Pseudomonas Contamination

If Pseudomonas is detected in your water system, swift action is essential to prevent further damage and restore system efficiency.

Data from remote monitoring and sampling results along with mechanical knowledge of the building should be reviewed and actioned appropriately.

An Integrated Approach to Water Treatment 

Preventing Pseudomonas requires a comprehensive and proactive strategy:

• Start with proper system design to eliminate high-risk features.
• Ensure pre-commissioning cleaning is thorough and compliant with industry standards.
• Use tailored water treatment plans that balance chemical and non-chemical solutions.
• Monitor and maintain your system regularly to address issues before they escalate.

By taking these steps, you can improve system efficiency, reduce maintenance costs, and ensure long-term water hygiene.

FAQs about Pseudomonas in water systems

What are acceptable levels of Pseudomonas in water in the UK?

For drinking water, the acceptable level of Pseudomonas aeruginosa is zero. This standard is crucial for health and safety compliance in healthcare and other sensitive environments.

How does Pseudomonas affect chilled water systems?

Pseudomonas can form biofilm in chilled water systems, blocking pipes and reducing efficiency. This increases corrosion, energy consumption, breakdown risk and operational costs.

How do I test for Pseudomonas in water?

A water treatment specialist will collect samples and send them to a laboratory for analysis. Tests identify the presence and levels of bacteria, guiding treatment decisions. 

Real time monitoring can detect the conditions in which Pseudomonas is likely to thrive, such as elevated oxygen and temperature levels.

Can Pseudomonas cause health problems?

In closed systems, human exposure is rare. However, in healthcare settings, Pseudomonas aeruginosa can cause infections in vulnerable individuals.

What’s the best way to prevent Pseudomonas in water systems?

Focus on proper design, pre-commissioning cleaning, on-going monitoring and regular maintenance. 

Summary 

Pseudomonas bacteria can cause serious challenges in closed water systems, from equipment damage to increased costs. A proactive, integrated approach ensures your system remains efficient, hygienic, and compliant with safety standards.

For expert advice on testing, prevention, and treatment, contact our team today.