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Our Mercian Science Laboratory are a UKAS Accreditation Laboratory and regarded as one of the best in UK.
Practical Advice & Solutions
Certified & competent consultants who work to a high set of standards
Waterman can provide all types of Water Sampling, such as Microbiological, Metal, Corrosion and Chemical. We use Mercian Science who are regarded as one of the best in their industry and are UKAS accredited.
Our clients are given access to our LIMS (Laboratory Management System). This operates as a central database for all results, which the client utilise to create trend reports and analyse data from specific locations, providing detailed information and total audit repository.
Legionella monitoring should be carried out where there is doubt about the efficacy of the control regime or it is known that recommended temperatures, disinfectant concentrations or other precautions are not being consistently achieved throughout the system.
Water Sampling Process
Conduct An Assessment & Determine Requirement For Water Sampling
Microbiological monitoring of domestic hot and cold water supplied from the mains is not usually required, unless the risk assessment or monitoring indicates there is problem.
Where monitoring for Legionella is considered appropriate in hot and cold water systems, sampling should be carried out in accordance with “BS 7592:2008 Sampling for Legionella organisms in water systems. Code of Practice” The complexity of the system will need to be taken into account to determine the appropriate number of samples to be taken. To ensure the sample is representative of the water flowing around the system and not just of the area downstream of the fitting, samples should be taken from separate hot and cold outlets rather than through mixer taps or outlets downstream of TMVs or showers. Samples should be clearly labelled with their source location and if collected pre – post flushing.
Undertake Water Sampling
In both hot and cold water systems, samples should be taken:
- If considered necessary by the risk assessment.
- From areas where the target control parameters are not met (i.e. where disinfectant levels are low or where temperatures are below 50°C (55°C in healthcare premises) for hot water systems or exceed 20°C for cold water systems).
- From areas subject to low usage, stagnation, excess storage capacity, dead legs, excessive heat loss, crossflow from the water system or other anomaly.
In cold water systems, samples should also be taken if required:
- From the point of entry (or nearest outlet) if the water is supplied from a private water supply or where the temperature of the incoming mains supply is above 20°C from the cold water storage tanks.
- From the furthest and nearest outlet on each branch of the system (far and near sentinel outlets).
In hot water systems, samples should also be taken as required
- From the calorifier hot water outlet and from the base of the calorifier, if it is safe to do so, as some systems are under considerable pressure.
- From the furthest and nearest outlet on each branch of a single pipe system (far and near sentinel outlets)
- From the furthest and nearest outlet on each loop of a circulating system (far and near sentinel outlets)
Analysis of Water Samples
Analysis of water samples for legionella should be performed in UKAS-accredited laboratories with the current ISO standard methods for the detection and enumeration of legionella included within the scope of accreditation.
The below tables give guidance on action to take if legionella is found in the water systems, including Healthcare.
|Legionella Bacteria (cfu/l)||Recommended Actions|
|>100 cfu/l and up to 1000||Either|
If the a positive, the system should be reached on sampled.
If similar results are found again, a review of the control measures and risk assessment should be carried out to identify any other remedial action required.
Disinfection of the system should be considered.
|>1000 cfu/l||The system should be resampled and an immediate review of the control measures and risk assessment carried out to identify any remedial actions, including possible disinfection of the system.|
Retesting should take place a few days after disinfection and frequent intervals afterwards into a satisfactory level of control is achieved.
|Legionella Bacteria (cfu/l)||Recommended Actions|
|> Not detected or up to 100 cfg/l||In healthcare, the primary concern is protecting susceptible patients, so any detection of legionella should be investigated and, if necessary, the system resampled to aid interpretation of the results in line with the monitoring strategy and risk assessment.|
|>100 cfg/l and unto 1000 cfg/l||Either: if the minority of samples are positive, the system should be resampled. If similar results are found again, review the control measures and risk assessment to identify any remedial actions necessary or if the majority of samples are positive, the system may be colonised, albeit at a low level. An immediate review of control measures and a risk assessment should be carried out to identify any other remedial action required. Disinfection of the system should be considered.|
|>100 cfg/l||This system should be resampled and an immediate review of the control measures and risk assessment carried out to identify any remedial actions, including possible disinfection of the system. Retesting should take place a few days after disinfection and at frequent intervals thereafter until a satisfactory level of control is achieved.|
All records are maintained in our LIMS systems and copies sent to our clients. All records must be kept for at least 5 years.