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Sorcerer Colony Counter used to assess drinking water quality

Vending machines and bottled water dispensers are commonplace in many organisations; however, nearly 30% of all the cold water samples taken from vending machines fail to meet the wholesome drinking water criteria stated in the Water Supply 2000 regulations. These regulations stipulate that wholesome drinking water should have no colour, odour, taste, or turbidity nor should it contain certain chemicals or micro-organisms.

The 4 main types of micro-organism that can be present in water are Coliforms, Cryptosporidium, Pseudomonas aeruginosa andEscherichia coli (E.coli).

case_ems_coliform1Coliforms are a large collection of various species of bacteria (both faecal and non-faecal). Contamination from these bacteria, does not pose any threat to human health, but can indicate that there may be more dangerous bacteria present in the supply, such as Salmonella.

Cryptosporidium are microscopic parasites found in water. Contamination occurs due to the presence of farm animals, particularly cattle, close to the water up-stream of a water treatment work’s intake point. Cryptosporidium are also found in highly turbid water (as found after heavy rain, when silts and other organic matter are washed into rivers).

Pseudomonas aeruginosa can infect any tissue if the body’s defences are low. When tissue is healthy, however, there are not likely to be any health effects and problems are most likely to be noticeable in the taste and odour of the drinking water.

Escherichia coli (E.coli) is a species of faecal coliform bacteria that only grows in the animal’s gut. Its presence in drinking water is therefore an indication of direct faecal contamination. This contamination occurs due to leakage of sewage onto the drinking water source, or where staff have employed poor hygiene practices.


case_ems_coliform2Health, safety & environmental consultancy Assurity Consulting has for over 25 years “monitored the health of buildings” through independent workplace audits, especially covering indoor air and water quality. Assurity Consulting UKAS accredited laboratory, based in Horsham, West Sussex processes around 35,000 samples each year. Rebecca Jupp and her colleagues are regularly look at drinking water quality using general TVC’s (Total Viable Counts) at a range of dilutions, E.coli/coliform identification, Pseudomonas aeruginosa identification and Legionella identification from water samples.

When analysing samples for the TVC analysis, 1ml of the sample is placed into 2 separate Petri dishes, 15ml of Yeast extract agar (YEA) is added to each and left to set. They are then incubated at their relevant temperatures for a set period of time. After incubation, they are read using the Sorcerer system. Each Petri dish is placed in the Petri-viewer and dark-field illumination provides a high contrast image for the system to analyse. Special algorithms are used to detect, separate and count the number of colonies. The Sorcerer system is linked to the Assurity Consulting database, allowing all counts to be automatically entered against each particular sample. Typically, up to 400 plates are counted per day.

The system has significantly reduced the time spent in reading these plates, and by linking to the company database, the risk of errors has also been reduced. Furthermore, certain bacteria such as aerobic spore bearing types, which have irregularly shaped colonies can be excluded from the counts using the image editor function. Assurity Consulting has a UKAS accredited laboratory, and any new procedures/equipment must be of a high standard. The accuracy of the Sorcerer colony counter ensures that there is no ‘drift’ during use and its audit trail facilities guarantee that it conforms to UKAS standards.

Assurity Consulting has a broad spectrum of customers ranging from major blue chip corporations and financial institutions to schools and colleges. They provide professional, qualified advice on a broad range of Environmental Auditing, Risk Assessment, Health & Safety, Training needs and specialist consultancy. Assurity Consulting expertise ensures clients receive independent strategic technical advice to achieve practical solutions and help meet legal compliance. This gives reassurance of providing a healthier, safer, and more productive environment.

Sorcerer Colony Counter

Find out more about Sorcerer Colony Counter.

Further information


Rebecca Jupp – Lab Supervisor