By: Gabriel Sanglay, PhD
With the addition of eight new microbiological methods for potable water testing to our portfolio, choosing the right tests might seem like a daunting task. In order to ensure safety and quality of your potable water supply or finished products, we offer a multitude of tests to meet your specific needs. Below is a description of tests and their provided information:
- Total Coliforms (quantitative)/Total Coliforms and E. coli by Colilert (qualitative): Coliform bacteria are defined as Gram-negative, nonspore forming rods that ferment lactose to produce acid and gas . Coliforms can include genera such as Escherichia, Klebsiella, Hafnia, Enterobacter, Citrobacter, etc. These bacteria are commonly found in the environment or in the digestive tracts/feces of animals and humans. While most coliforms are not harmful to human health, they can act as indicators of the presence of pathogenic bacteria and/or fecal contamination [1, 2]. Per the EPA’s National Primary Drinking Water Regulations, the maximum contaminant level goal (MCLG) of coliforms is zero, while the maximum contaminant level (MCL) is no more than 5% total coliform positive samples within a month . For facilities that test less than 40 samples per month, no more than one sample can be total coliform positive in a month . Even though the EPA’s Total Coliform Rule only requires an absence/presence result per 100ml of potable water, quantitative data can provide information of the magnitude of contamination . We offer both a quantitative membrane filtration that includes coliform confirmation, as well as a qualitative method that provides the absence/presence of total coliforms and E. coli.
- Heterotrophic Plate Count (HPC; Pour Plate at 35°C, Membrane Filtration at 35°C or 22°C): HPC, which is also known as standard plate count, is a procedure that measures the amount of live, culturable microorganisms in water . HPC does not have any negative health effects . We offer a standard pour plate method, or membrane filtration of 100ml at two different temperatures (the lower temperature method may improve recovery of stressed or fastidious bacteria) to monitor HPC in your water.
- Our other methods (Yeast and Mold Enumeration, Enumeration of Sulfite-Reducing Anaerobic Bacteria, Enumeration of aeruginosa by Rapid PA) are not required by EPA, but provide information on the cleanliness of the potable water supply, or quality issues with finished product.
- Fungi (which includes yeasts and molds) are present in the environment and can make their way into drinking water systems . These organisms may be pathogenic, allergenic, or toxigenic and can be of particular concern to immunocompromised patient in hospitals . They may also affect drinking water quality, affecting taste or odor in water sources or finished products .
- Sulfite-reducing anaerobic spore-forming bacteria (notably, Clostridium perfringens) can be resistant to disinfection processes, but their presence can serve as an indicator of protozoa, fecal contamination, or the effectiveness of filtration/disinfection processes .
- Pseudomonas aeruginosa can be an opportunistic bacterial pathogen, but rarely causes serious illness . It is a common environmental organism, and its presence in potable water or finished products may affect taste, odor, and turbidity .
Please note, that while these are validated methods, they are not EPA certified nor is NQAC Dublin an EPA certified lab.
If potable water/finished product testing is of interest to you, NQAC Dublin can help. Below, you will find links to our technical datasheets for more information on our testing options. If you have further questions, please do not hesitate to reach out to our Customer Service team at NQAC Dublin at firstname.lastname@example.org.
- ISO-4831:2006 – Detection & Enumeration of Coliforms – Most Probable Number Technique – Micro
- LI-10.112 – Yeasts and moulds enumeration – Micro
- LI-10.114 – Sulfite-Reducing Anaerobic Spores Enumeration – Micro
- LI-10.222 – Enumeration of P. aeruginosa by Rapid PA – Micro
- SMEWW 9215B – Heterotrophic Plate Count, Pour Plate – Micro
- SMEWW 9215D – Heterotrophic Plate Count, Membrane Filtration – Micro
 ScienceDirect. (2020). Coliform Bacteria. Retrieved from: https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/coliform-bacteria
 Environmental Protection Agency. (2009, May). National Primary Drinking Water Regulations Complete Table. Retrieved from: https://www.epa.gov/sites/production/files/2016-06/documents/npwdr_complete_table.pdf
 Standard Methods for the Examination of Water and Wastewater, 23rd ed. (2017). Section 9222B – Standard Total Coliform Membrane Filter Procedure Using Endo Media. p. 9-82 to 9-88.
 Standard Methods for the Examination of Water and Wastewater, 23rd ed. (2017). Section 9215 – Heterotrophic Plate Count. p. 9-53 to 9-856.
 Hageskal, G. and others. (2009). Review – The Study of Fungi in Drinking Water. Retrieved from: https://www.sciencedirect.com/science/article/pii/S0953756208002414
 World Health Organization. (2017). Guidelines for Drinking-Water Quality, 4th ed. Chapter 11: Microbial Fact Sheets. pg. 231-306. Retrieved from: https://www.who.int/water_sanitation_health/publications/gdwq4-with-add1-chap11.pdf?ua=1