Pseudomonas is a bacteria often found in closed circuit water systems, once mainly an issue in London. Now, it is appearing in buildings across the UK. Its spread must be controlled to protect pipework and HVAC systems.
While it can be harmful to health, people are rarely exposed to a closed system. The main concern is the damage it causes to HVAC equipment. Effective water system design, essential pre-commissioning cleaning, and planned maintenance are necessary to prevent Pseudomonas.
What is Pseudomonas?
Pseudomonas in water is a group of 191 strains of aerobic, gram-negative bacteria that include harmful pathogens. These bacteria are adaptable and thrive in different environments, quickly colonising water tanks, food storage, preparation areas, and water processing facilities.
Once established, Pseudomonas creates a thick green/yellow biofilm that is hard to remove. This biofilm is made of siderophores, which are strong, water-soluble iron-chelating compounds that bind to other metals in the water.
Due to the harmful effects on human health and ecosystems, regular tests are necessary to detect Pseudomonas in commercial water systems, along with treatment procedures to control its growth.
What are the Risks of Pseudomonas in Drinking Water?
Pseudomonas causes diseases in humans, plants, and animals.
Humans & Animals
The Pseudomonas strain, like the waterborne Pseudomonas aeruginosa, often causes common hospital-acquired infections. Many hospitals and clinics struggle with it persistently. The bacteria secrete proteins that lead to pneumonia, blood poisoning, and urinary infections. P. aeruginosa spreads easily and resists or is hard to treat with antibiotics. Some strains attack white blood cells in mammals, including humans, cattle, sheep, and dogs.
Fish
P. aeruginosa primarily infects humans. P. plecoglossicida causes gastric swelling and haemorrhaging in fish.
Plants & Fungi
Some Pseudomonas strains are harmful to plants. The P. syringae family causes diseases in many crops. Each strain targets specific hosts. P. tolaasii, a harmful bacteria, affects edible mushrooms, potentially causing significant damage to agricultural businesses.
Preventing Pseudomonas from Growing and Multiplying
Preventing Pseudomonas begins with proper water system design and installation. Avoid dead legs and capped pipes to prevent stagnant conditions that allow Pseudomonas to grow. Loop out and circulate water regularly in such systems.
According to BSRIA guidelines, new water systems should undergo pre-commissioning cleaning to ensure cleanliness from the start.
Once operational, perform routine microbiology and chemistry analyses to ensure water is free from harmful bacteria. Maintain a consistent water temperature of 20°C to deter Pseudomonas, as it thrives in low temperatures. Keep chlorine levels within specific parameters and apply regular biocide treatment to prevent contamination. These measures are crucial in healthcare environments.
How do you Test for Pseudomonas in Water Treatment?
A water treatment specialist collects a sample for testing. The testing method differs for Pseudomonas species and Pseudomonas aeruginosa.
Testing for Pseudomonas Species
To test for Pseudomonas species, concentrate the water sample using a filtration system if needed. Add it to a selective agar plate with antibiotics that block other bacteria. Place it in an incubator for Pseudomonas to grow. If growth occurs, perform a biochemical test by adding bacterial material to an “oxidase reagent.” A colour change indicates a positive result.
Testing for Pseudomonas Aeruginosa
Testing for Pseudomonas aeruginosa uses a different agar and includes confirmatory tests for factors like casein hydrolysis and UV fluorescence. Zero Pseudomonas aeruginosa is the acceptable level. All samples are collected and tested within 24 hours.
Positive Uses Of Pseudomonas
Although Pseudomonas is often viewed negatively, it has beneficial uses. It acts as a bioremediation agent to break down chemical pollutants in water, such as cyanide and aromatic organic compounds.
In nature, Pseudomonas helps form ice crystals and rain in the lower atmosphere. Bacterial infections can cause issues for manufacturers. However, proper equipment and water treatment can control bacterial levels and prevent contamination.
Closed water systems – How Do You Deal with a Pseudomonas Contamination?
Preparation
When Pseudomonas contamination is found in a closed water system, plan your approach carefully before beginning a water treatment process.
Is there a clean water source available for flushing and refilling?
A water supply free of Pseudomonas is critical; otherwise, the closed water system will be recontaminated. A mains water supply with a short pipe run should offer Pseudomonas-free water. Sample the supply water when possible to confirm this.
Do you and your team understand the layout of the pipework and equipment?
Closed water systems can be complex, with extensive pipework and equipment. The treatment chemicals must reach all parts of the system for success. Dead legs, blind ends, poor pumps, and broken valves can block circulation and hinder treatment. Use a schematic drawing to ensure you understand the system and add the correct chemical amounts. Know the system’s materials, as this affects chemical choice.
Is the water treatment specialist skilled for the job?
Water treatment is specialised, so checking the chosen organisation’s skill and ability is crucial. Experience with similar cases is the best evidence. References or testimonials can aid in selecting a competent specialist.
Pre-treatment
After proper preparation, the next step is pre-treatment. This makes the system ready for effective biocidal water treatment. The level of pre-treatment needed depends on contamination. This could be a systemic issue or isolated to stagnant parts that are now in use.
Is the slime in the system completely removed?
Pseudomonas organisms produce a slime layer that’s hard to wash away. This slime causes biofilm and problems like blockages in the closed water system. It also protects the micro-organism from biocidal chemicals, allowing Pseudomonas to survive even after treatment. If the slime isn’t cleared, biocidal treatment won’t work, and contamination will keep returning. A large amount of water may be needed for flushing. This step should not be overlooked or compromised. Effective flushing reduces long-term water treatment costs.
Decontamination
Once the system is clear of slime, use a suitable disinfectant to eliminate any leftover Pseudomonas effectively. Ensure the chosen biocide is effective against Pseudomonas. Use field trial test data for evidence. Achieve the right concentrations and contact times for successful decontamination. Consult your water treatment specialist for this information.
Refilling
After completing the biocidal treatment, refill the closed water system with the proper chemical agents. Ensure the water source is free from Pseudomonas contamination to prevent recontamination.
Have the correct water treatment chemicals been added?
Never fill closed water systems with untreated water. Once filled with treated water, avoid leaving them stagnant for long periods. Consult a competent water treatment specialist to select the appropriate chemicals for the specific system and materials.
The chemical treatment usually includes corrosion inhibitors and a biocidal agent to reduce the risk of Pseudomonas contamination. Sampling and testing are crucial to confirm the correct chemical concentrations and ensure the system maintains an acceptable level of water quality.
Closed water systems are designed to be “tight,” minimising water and chemical loss. Sampling and testing of chemical levels and bacterial activity should be done quarterly as a best practice. The frequency of these checks should depend on the system’s control level, usage, complexity, and condition.
Contact a Specialist Today to Deal with Pseudomonas Bacteria in Your Water Systems
An integrated approach is essential for water hygiene. Taking the right steps during design and construction, followed by pre-commissioning cleaning and ongoing water treatment, can control Pseudomonas.
Contact us to find solutions for managing Pseudomonas bacteria, helping you save money, reduce chemical use, and lower maintenance needs.
FAQs
What kills Pseudomonas bacteria?
Pseudomonas bacteria can be killed using specific biocidal agents. These agents need to be effective against this type of bacteria. It is essential to confirm the correct concentrations and contact times for the biocidal treatment. Consultation with a water treatment specialist is advised to ensure the treatment is successful.
Can tap water be contaminated with Pseudomonas?
Pseudomonas aeruginosa is present in soil, water, and on plants. This pathogen requires minimal nutrients to survive, allowing it to persist for a long time. It is commonly found in carbon filters, cooling towers, drinking water dispensers, bottled water, and water taps.
Can Pseudomonas survive in chlorinated water?
Tests on chlorine disinfection showed that Pseudomonas aeruginosa strains resisted a 0.5 ppm concentration. However, exposing them to 1.5 ppm of chlorine for 30 minutes eliminated 60% of the strains.
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