Karina Jones, an IHEEM-registered Authorising Engineer (Water) at Eta Projects, and a member of the Institute’s Water Technical Platform, considers some of the most prevalent hazardous waterborne bacteria found in healthcare premises, and the key steps to keep their growth and transmission in check, and thus safeguard patients, staff, and visitors, against infection.
In England and Wales, the Drinking Water Inspectorate (DWI) provides independent reassurance that water supplies are safe, and that drinking water quality is acceptable, while the World Health Organization produces international norms on water quality and human health via guidelines for regulation and standard setting worldwide. Water quality is determined by its origin, and can often be altered or compromised by the way water is managed – especially in large buildings, where complex domestic hot and cold water systems can provide a suitable environment for water quality to diminish – due to factors including incorrect temperature management, water stagnation, exposure to incorrect components, non-Water Regulations Advisory Scheme (WRAS)-approved installations, or the addition of biocides.
Regular testing
To implement appropriate water management within buildings (especially in healthcare environments), incoming mains water should be tested to drinking water parameters1 to obtain an understanding of its quality. This is often overlooked at the start of building projects, potentially resulting in unnecessary expense, and delaying occupation. In nature, water is mineralised when it filters through different rock layers from origin to source, which influence the degree of mineralisation. Natural mineral water thus contains a different mineral concentration. For infants, athletes, or pregnant women, the concentration of certain minerals is key. Minerals such as sodium may present at too high a quantity, and others, like magnesium, at too low a level.
Sodium levels
The appropriate sodium level is also essential to the human body, with Public Health England (PHE) recommending a daily UK adult allowance (RDA) of 2.4 g. Together with chloride and potassium, sodium is among the most important electrolytes for the body – regulating water balance, influencing blood pressure, kidney function, and acid-base balance, and controlling cell function and our immune systems. In fact, many cellular processes are only possible through sodium, which contributes to the normal functioning and health of skin, bones, muscles, and connective tissue. Sodium levels in drinking water vary significantly depending on location. In healthcare environments, infants and young children, and those with high blood pressure or impaired renal function, should only be exposed to low sodium levels in drinking water, and where water is undergoing softening, it must not enter the healthcare facility’s potable water distribution system.
Key testing parameters
Testing of incoming water quality will include microbial level, mineral, sodium load, and pH value. The pH standpoint water values may vary between 6.5 and 9.5. pH levels are determined by water’s acidity or alkalinity, identified by the number and activity of free hydrogen ions dissolved in it. The ideal level for drinking and consumption (tap water) is 7-8.5 pH. Acidic drinking water damages cementlined pipes, while galvanised steel is prone to corrosion from a pH below 7.5. Copper lines must not be used if the pH is below 7, as acidic water washes copper from the pipes. Too much of this trace element is especially dangerous for babies and children. Knowing the pH level of drinking and tap water is key to both good water quality and waterborne pathogen control.
Water hardness
Water hardness levels play a huge part in water system maintenance due to scale build-up. Scale or limescale is a hard, rocklike deposit of calcium or magnesium salts that forms in heat exchangers, cooling tower packing, and other water-fed equipment, due to heat. Scale formation impairs heat transfer and flow, and can be a breeding ground for Legionella. To control waterborne pathogens within domestic hot and cold water systems, we must fully understand the mains incoming water quality before establishing a suitable water management plan. Water temperature is just one aspect of water management. To spread through a water system of any size, Legionella requires both an optimum temperature range, i.e. between 20 and 45 °C, and available nutrients.
Suitable nutrients for Legionella
The need for suitable nutrients is where hard water becomes a potential Legionella issue. Nutrients are typically present in the form of biofilm, and biofilms harbour microbes that Legionella bacteria can use as nutrients… and, of course, nutrients encourage bacteria growth. There are three elements necessary for biofilm to occur:
1 Moisture – this allows the bacteria to grow / spread.
2 Bacteria – either a single species or several.
3 A surface for the bacteria to adhere to
Biofilms will adhere to many surfaces – from skin to metal and plastic, and act as a very effective ‘hideout’ for bacteria, which can be very difficult to remove. Effective hygiene, keeping the water moving to prevent stagnation and build-up of the necessary nutrients for bacterial growth, and keeping the cold water cold, and the hot water hot, are all key.
Water sampling techniques
To confirm effective microbial control, sampling in both domestic and industrial water systems is essential. However, the importance of correct water sampling procedures is often overlooked. Before undertaking microbial sampling, one should have the correct information, understand the reason, note the time of sampling, and the extent of pipework to be sampled, know the type of analyses required, who will conduct the process, and the sample processing location – e.g. an ‘in-house’ or external laboratory
Appropriate sample storage facilities, and the timeframe for transporting the sample bottles are key, since some analysis requires the containers to be stored in a cool place for a set maximum period. Water collected for P. aeruginosa analysis, for example, should be processed within two hours, but if this is not possible, should be refrigerated within two hours, kept at 2-8 °C, and processed within 24 hours. Samples must also be kept apart from both hot and other cold samples to prevent temperature ‘cross-contamination’
Need for sufficient training
Personnel undertaking sampling should have sufficient training and information to perform the task correctly, and a general understanding of the bacteria’s characteristics, to appreciate the steps required to maintain the samples’ bacterial load until the laboratory receives them. The time between sample collection and analysis should generally not exceed six hours, with 24 hours considered the absolute maximum. All Mycobacterial analysis requires different storage and / or transport requirements. Samples for Legionella analysis can be stored at an ambient temperature, and should preferably be delivered to the lab within 24 hours, but after no more than 48, with Pseudomonas aeruginosa samples kept at between 2 and 8 °C, and processed within 24 hours. Sampling should identify the quality of the water (total viable counts of bacteria, or TVCs) both from the supply company, and at point of use. Any significant variation between the two has important implications for remedial action, as TVCs are a good indicator of general water quality.
Taste or odour problems
Where taste or odour problems in drinking water exist, microbiological monitoring for TVCs may be necessary. However, routine microbiological monitoring for TVCs is not recommended, as there is no direct association with TVCs and waterborne pathogen presence. Samples must be taken from locations representative of the water source, treatment plant, storage facilities, distribution network, and delivery points. In selecting sampling points, each locality should be considered individually, but the following general criteria apply:
Sampling points should be selected so samples are representative of the different water sources.
The sample points should include areas that yield samples representative of the conditions at the most unfavourable sources or places in the supply / distribution system – such as unprotected sources, loops, low-pressure zones, ends of the system, and high-risk water exposure areas for patients / the public.
Sampling points should be uniformly distributed throughout a piped distribution system, with the number proportional to the number of links / branches.
They should be located so that water can be easily sampled from reserve tanks (cold water tanks, RO units, calorifiers, and cooling towers etc.), and water components.
In systems with more than one water source (mains water, borehole water supply), the sampling point location should factor in the area and number of inhabitants served by each source.
There should be at least one sampling point directly after the clean water outlet from each treatment plant.
Sampling points in the water distribution system may be classified as ‘fixed’, ‘random’, or ‘variable’.
Fixed samples
Fixed samples are useful when results must be compared over time, but limit the possibility of identifying local problems. Sampling regimes using variable or random outlets are more likely to detect local problems, but less useful for analysing changes over time. Areas sampled should include hydrotherapy pools, augmented care and maternity wards, burns units, and areas housing the immunocompromised, elderly, and very young.
When sampling water that may contain even traces of chlorine or other biocide, the biocide must be inactivated, or microbes may be killed during transit, giving an erroneous result. The sample bottles should thus contain sodium thiosulfate to neutralise any chlorine, copper, and silver. Stringent hygiene is key throughout; this includes the box used to carry samples, which should be cleaned and disinfected after each use
Importance of risk assessment, testing, and monitoring
1: Risk assessment
To implement a correct scheme of control for Legionella and other waterborne pathogens, a risk assessment must be undertaken of the water distribution system, water components, and the area within which individuals could be exposed to water, including water aerosols. Legionella risk assessment must be by a qualified and competent person(s), who must factor in the physical aspects (i.e., water source, water components, and water distribution system), the environmental aspects, and the channels via which the waterborne pathogens can affect patients / the public.
The most serious form of disease caused by Legionella is Legionnaires’ disease, predominantly caused bv L. pneumophila bacteria. Legionellae are opportunistic pathogens, and normally inhabit warm, moist, or aquatic environments, growing there in association with other organisms.
Legionella bacteria transmission to humans only occurs via breathing in particles remaining in the air, when water in a droplet evaporates, leaving airborne matter such as Legionella bacteria held within the aerosols. The bacteria can also be inhaled into the lungs, and via aspiration.2 Person-to-person transmission does not occur.
When addressing Pseudomonas aeruginosa bacteria, risk assessments must include aspects of hygiene / hygiene control. Work with potable water requires scrupulous personal hygiene to prevent system contamination. P. aeruginosa can be found in faeces, soil, water, and sewage. Able to multiply in aquatic environments, and on the surface of suitable materials in contact with water, the bacterium has been isolated from a range of moist environments – such as sinks, water baths, hot water systems, showers, and spa pools. P. aeruginosa can be transferred from person to person via hand-to-hand and hand-to-surface contact.
2: Testing and monitoring
Water sampling is a starting point in understanding water quality at a specific time / place. However, to ensure that quality is properly monitored / maintained, we must take specific steps – including temperature testing to ensure that domestic hot and cold water are stored and distributed at the correct temperature. Cold water should be stored and distributed at below 20 °C, while the hot water flow temperature from the calorifier should be kept at a minimum 60 °C. The temperature should be at a minimum of 55 °C on flow and returns to all outlets (in healthcare), and at the start of the hot water return, and at a minimum of 50 °C at the final connection to the calorifier. Temperature monitoring is key in Legionella control
Where Legionella bacteria in water systems are difficult to control, a biocide may be added. Biocides must, however, be monitored at the frequency stipulated by the HSE’s Technical Guidance HSG 274 Part 2: The control of legionella bacteria in hot and cold-water systems, with levels not exceeding the allowed drinking water parameters.
pH-sensitive processes
While chlorine dioxide is unaffected by water pH or hardness, the copper and silver ionisation processes are pHsensitive, and dosing levels may need increasing for pH levels over 7.6. Tests for pH levels should be undertaken at the time of monitoring for copper and silver levels in domestic hot and cold water systems when used as a biocide. To ensure accurate testing and monitoring of temperature or biocide chemical levels, all equipment requiring calibration must be calibrated by an accredited calibration service, at the manufacturer-specified intervals. Where concerns over drinking water quality exist, testing should be regular. Such water should not contain pathogenic microorganisms, or bacteria indicative of faecal pollution.
Keeping water in a clean environment
To minimise contamination, it is important to keep water in a clean environment protected from outside contaminants (i.e. dirt, dust, rust, scale, and animal faecal contamination), and to keep it moving. Regular water system monitoring, cleaning, and disinfection, are essential, together with monitoring of low-use outlets.
HTM 04-01: Safe water in healthcare premises: Part B: Operational management, recommends establishing a multidisciplinary Water Safety Group to develop and manage a Water Safety Plan (WSP), and advise on remedial action when water systems or outlets are found to be contaminated.
Microorganisms of significance – Pseudomonas and Mycobacteria
Microorganisms of significance are those falling under the category of antibioticresistant bacteria. Pseudomonas aeruginosa is a multi-drug-resistant pathogen recognised for its ubiquity; it has no need for organic growth factors, and is able to harness over 75 organic compounds for growth, making it highly resistant to many antibiotics.3 An aerobic, gram-negative, rod-shaped bacterium (very similar to the Legionella bacterium in shape) with polar flagellum, its shape helps it swim in any water system, even against the flow. Found in soil, water, skin flora, and most man-made environments, it thrives both in normal and hypoxic atmospheres, and can colonise many natural and artificial environments. It uses a wide range of organic material for food, but does not rely entirely on a food supply (the bacteria have been observed to grow in distilled water)
A risk to the immunocompromised
The bacterium almost never infects healthy tissue, yet there is hardly any tissue it cannot infect where host defences are compromised. P. aeruginosa infections are increasingly antibiotic-resistant, and the organism may acquire resistance during therapy. Infection can be found on and in medical equipment. The wide-ranging areas it affects, and its impacts, include:
The urinary tract.
Respiratory systems.
The skin.
Soft tissue.
Bacteraemia and septicaemia.
Bones and joints
Gastrointestinal.
Central nervous system.
Ear infections
Keratitis caused by P. aeruginosa can cause blindness, and the bacterium also affects patients with severe burns, cancer, and AIDS. Control of P. aeruginosa bacteria in healthcare settings is always challenging, making clinical risk assessments essential, as per HTM 04-01 and BS8580-2:2022: Part 2: Risk assessments for Pseudomonas aeruginosa and other waterborne pathogens – Code of practice, to establish the correct scheme of control.
Strict hygiene and good training
Key in controlling and eliminating P. aeruginosa are strict hygiene procedures, supported by relevant training and information for Estates personnel, housekeeping / cleaning staff, and everyone working in, and visiting, a healthcare environment. Information on hand hygiene should be clearly encouraged, especially as P. aeruginosa transmission is possible person-to-person. The key is to prevent the bacteria taking hold in the water systems and areas where contamination can occur (damp surfaces). Any bacteria will – in a suitable environment – establish a biofilm, which is extremely difficult to eliminate from surfaces. Sources of contamination leading to biofilm formation include:
Dirty taps, shower heads, and adjustable flow shower heads.
Rusty and scaled-up flow straighteners.
Unsuitable materials.
Contamination during water systems’ construction and repair.
Non-compliant hot / cold watertemperature.
Water stagnation (often in low-use outlets).
Badly designed cold water tanks and expansion vessels.
Complex components incorporating rubber and plastic.
Foul drainage, which can become blocked.
Poor water flow.
Disposal of body fluids and environmental cleaning agents at clinical washhand basins.
Washing of patient equipment in such basins, and their use for storing equipment awaiting decontamination.
Contaminating the tap by touching the spout when handwashing.
Incorrect tap and shower cleaning. (Taps should be cleaned before the rest of the clinical washhand basin, with care to avoid transferring contamination from basin to basin).
Using non-fillable single-use bottles for antimicrobial hand-rub / soap.
Ensuring that reusable containers containing environmental cleaning agents are used in a way that protects them from contamination with P. aeruginosa.
Ensuring appropriate positioning of soap and antimicrobial hand-rub dispensers. (The compounds in these products can be a nutrient source to some microorganisms).
Keeping areas dry, since bacteria thrive in moist environments.
Other difficult-to-eradicate bacteria
Another difficult-to-eradicate bacterium, Klebsiella pneumoniae, can affect middle-aged and older men, and is becoming antibiotic-resistant. Its natural environmental niches are the soil, skin, mouth, and intestines. The Gram-negative bacterium can cause healthcareassociated infections including pneumonia, bloodstream infections, wound or surgical site infections, meningitis, and sepsis. For infection transmission, a person must be exposed to the bacterium; i.e. K. pneumoniae must enter the respiratory tract to cause pneumoniae, or the blood to cause a bloodstream infection
Preventing Klebsiella infections spreading requires specific infection control precautions, including strict hand hygiene – preferably using an alcoholbased hand rub (60-90%), or soap and water if hands are visibly soiled. Alcoholbased hand rubs are effective against these Gram-negative bacilli, and wearing gowns and gloves when entering rooms housing patients with Klebsiella–related illnesses is essential. Healthcare facilities must also follow strict cleaning procedures.
To prevent infection spread, patients also should clean their hands very frequently, including:
Before preparing or eating food.
Before touching their eyes, nose, or mouth
Before and after changing wound dressings or bandages.
After using the toilet.
After blowing their nose, coughing, or sneezing
After touching hospital surfaces.
Benefits of strict hand hygiene
Correct hand hygiene in healthcare must be strictly observed to slow down, if not eradicate, hazardous microorganisms. The COVID-19 pandemic highlighted its importance to everyone
The other mycobacterium of concern is Nontuberculous mycobacteria (NTM),4 with pulmonary infections a growing global issue, especially among those with pre-existing health conditions. BS 8580-2 :2022 Part 2: Water quality Risk assessments for Pseudomonas aeruginosa and other waterborne pathogens – Code of practice, emphasises the importance of non-tuberculous mycobacteria, or NTM – a group of bacteria that causes rare lung infections sometimes known as NTM pulmonary disease
Risk assessment key
Risk assessment is important in determining the correct scheme of control for NTMs in areas housing severely immunocompromised patients – including transplant units, haematologyoncology units, cystic fibrosis units, and ‘high-risk’ augmented care units. NTM predominantly cause pulmonary infections, but also skin, soft tissue, and post-operative infections. The bacteria are found in soil and water, and can be present in man-made water systems. Like other water-associated opportunistic pathogens, non-tuberculous mycobacteria are present in the environment, and can proliferate in drinking water systems, attaching to a variety of surfaces, and establishing biofilms not too dissimilar to Pseudomonas aeruginosa and Legionella bacteria – which are among select bacteria able to enter, and survive within, amoebae. These properties confer the resistance needed to survive conventional water treatment, and proliferate in drinking water systems despite the presence of disinfectant residuals. Their resistance to chlorine has been recognised as key to the survival, colonisation, and persistence, of environmental mycobacteria in water distribution systems.
Generic variability
Identifying and quantifying NTM in environmental samples is complicated by genetic variability among species, making it challenging to determine if clinically relevant NTM are present. Sampling frequency should be agreed by the WSG and the IPC team. Analysis for Non-Tuberculosis Mycobacteria is normally covered within the Environmental Mycobacteria analysis (EM). The bacteria are principally transmitted by ingestion, inhalation, and inoculation from environmental sources, rather than person to person
A BBC News story last November highlighted a case of Mycobacterium abscessus – a group of rapidly growing bacteria of particular concern to lung transplant patients and other immunosuppressed individuals.5 This Mycobacterium species is currently not monitored in healthcare, but this is something that needs addressing.
Mycobacterium abscessus is a bacterium distantly related to the ones that cause tuberculosis and Hansen’s Disease (Leprosy). Part of a group of environmental mycobacteria, it is found in water, soil, and dust, and has been known to contaminate medications and medical devices.
Skin and soft tissue diseases
M. abscessus can cause a variety of infections. HAIs caused by it are usually of the skin and the soft tissues underneath. It also causes serious lung infections in those with chronic lung diseases like cystic fibrosis.6 People with open wounds, or who receive injections without appropriate skin disinfection, may also be at risk.
UKAS accreditation and choosing a laboratory
Since water analysis provides vital information, it should be undertaken in accordance with current ISO standard methods. In the UK, laboratories and other organisations providing certification, testing, inspection, and calibration services, should be accredited by UKAS. Water sample analysis for Legionella should be performed in UKASaccredited laboratories. The current ISO standard methods for the detection and enumeration of Legionella are included within the scope of accreditation to EN ISO 17025: General requirements for the competence of testing and calibration laboratories.
The Health and Safety Executive HSG 274 Technical guidance Part 2 recommends that these laboratories take part in a water microbiology proficiency testing scheme, such as that run by Public Health England (PHE), or an equivalent ISO 17043-accredited scheme. Alternative quantitative testing methods may be used if validated using ISO 17994: Water quality – Requirements for the comparison of the relative recovery of microorganisms by two quantitative methods, and the tests meet the required sensitivity and specificity. This standard was last reviewed and confirmed in 2019, and is still current.
Standards writing for many different sectors
The International Organization for Standardization (ISO)7 is the international organisation that writes standards for many sectors, ISO 9001 and 14001 being among the best known. UKAS oversees the standards in the UK, assessing organisations including laboratories against recognised standards. Not all ISO standards require UKAS accreditation. ISO 9001 is a standard used for certification, rather than accreditation, and thus UKAS does not assess or provide accreditation to this standard. So, what is the difference between accreditation and certification?8
A written assurance
Certification is a third party’s written assurance on the conformity of a service, product, or process, based on specified requirements provided by some form of education, audit, assessment, or external review. The third party provides certification by indicating full satisfaction with a service, product, or process. It is important to be certified by an official certification body
Accreditation refers to formal recognition on the competency towards specified standards by an authoritative body like UKAS. These bodies also test and supervise organisations tasked with testing, calibrating, inspecting, and certifying, firms against internationally set standards.
Selecting the correct laboratory is important to ensure that water analysis is undertaken within specified timeframes. The HSE’s HSG 274 Technical guidance stipulates that water sample testing for Legionella should be performed in a UKAS-accredited laboratory, although alternative quantitative testing methods may be used if validated using ISO 17994, and they meet the required sensitivity and specificity
On-site rapid analysis
Although no replacement for a UKAS laboratory test, on-site rapid analysis technology can provide invaluable reassurance to, for example, Maintenance managers, Responsible Persons, and Duty Holders. Using on-site testing to quickly identify the presence of Legionella enables hospital management teams to make faster decisions on the correct remedial actions. Using rapid on-site testing can significantly reduce Pseudomonas aeruginosa positive outlets through a faster sampling turnaround, and more rapid implementation of remedial work, to return outlets to use considerably more quickly.
Water sampling for both Legionella and Pseudomonas aeruginosa bacteria must be carried out by a competent, trained, and methodical individual fully familiar with HTM 04-01 and the HSE’s HSG 274 Technical guidance, and the following British Standards:
BS 7592: 2022 Sampling for Legionella bacteria in water systems – Code of practice.
BS 8554: 2015 Code of practice for the sampling and monitoring of hot and cold-water services in buildings.
Guidance documentation
HTM 04-01: Safe water in healthcare premises. Department of Health and Social Care. 20 May 2016.
Health Technical Memorandum 04-01 Part C: Pseudomonas aeruginosa – advice for augmented care units. Department of Health. March 2013.
BS 8580-1: 2019 Water quality – Risk assessments for Legionella control – Code of practice.
BS 8580-2: 2022 Water quality Part 2: Risk assessments for Pseudomonas aeruginosa and other waterborne pathogens – Code of practice.
DWI, 2021. Legislation, Drinking Water Inspectorate. DWI. www.dwi.gov.uk/ water-companies/legislation/
The Water Supply (Water Fittings) Regulations 1999. WRAS. n
BS 7592: 2022 Sampling for Legionella bacteria in water systems – Code of practice.
Health Technical Memorandum 04-01: Safe water in healthcare premises. Part B: Operational management. Department of Health. 20 May 2016.
Karina Jones
Karina Jones MIHEEM, MIET, MWMSoc, MWES, is an IHEEMregistered Authorising Engineer (Water), and a member of the Institute’s Water Technical Platform, who gained extensive water management company experience before becoming an AE (Water) at consulting engineers, Eta Projects. She specialises in healthcare.
She is also a member of the Water Management Society, the Institution of Engineering and Technology, and the Women’s Engineering Society. She has extensive experience providing advice on water hygiene management, advising clients on the legal drivers for statutory obligations and ACOP L8 compliance, and providing comprehensive guidance on microbiological waterborne contamination in water systems to NHS Trusts.
She delivers regular water hygiene training, and works closely with soft FM personnel and Estates Departments, and others involved with water hygiene, through regular communication systems, audits, testing and verification, reviews of Water Safety Plans, and Written Schemes of Control.
References
1 Vaerewijck MJM, Huys G, Palomino JC, Swings J, Portaels F. Mycobacteria in drinking water distribution systems: ecology and significance for human health. FEMS Microbiol Rev 2005; Nov 29 (5):911-34.
2 Aspiration Pneumonia Symptoms. Treatment and Information. Patient online. https://tinyurl.com/2k33yse4 3 Qureshi S. MD, FACP. (Chief Editor: Bronze MS. MD) Pseudomonas aeruginosa Infections Medication. Medscape.
3 March 2020. https://tinyurl. com/ypfpw792
4 Dowdell K, Haig S-J, Caverly L-J, Shen Y, LiPuma JJ, Raskin L. Nontuberculous Mycobacteria in Drinking Water Systems – The Challenges of Characterization and Risk Mitigation. Curr Opin Biotechnol 2019 Jun; 57: 127–136. https://www.ncbi. nlm.nih.gov/pmc/articles/PMC6924000/
5 BBC News. 3 November 2022. Papworth Hospital: Contaminated water led to women’s deaths – inquest. https://tinyurl. com/7ahsbknh
6 Mycobacterium abscessus in Healthcare Settings. Centers for Disease Control and Prevention. www.cdc.gov/hai/ organisms/mycobacterium.html
7 International Organization for Standardization. Wikipedia. https://tinyurl.com/2ww9ummz
8 Certification and accreditation. Difference Between Certification and Accreditation. DifferenceBetween.net. https://tinyurl.com/2p8epump