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NSF/ANSI 55 – Ultraviolet Microbial Water Treatment Systems


Purpose and Goals

  • Evaluate and compare the antimicrobial efficacies of a novel UV disinfectant product/device against a variety of planktonic microbes in flowing water under different flow rates in laboratory-controlled testing. 

Materials and Methods

  • This testing will be performed as a modification of the Standard Test Method NSF / ANSI 55-2022 – Ultraviolet Microbiological Water Treatment Systems. 
    • This standard is intended for UV systems in the range of 240 nm – 300 nm for point-of-use (POU) and point-of-entry (POE) installations.
  • The novel UV disinfectant product/device will be connected to a holding tank, liquid pump, and collection tank. The holding tank will be decontaminated, then filled with filtered water (tested to meet NSF / ANSI 55-2022 specifications for pH, UV Transmission, Turbidity, Temperature, Total Dissolved Solids, and Chlorine) and sterile Phosphate Buffered Saline (PBS) added as needed.
  • The holding tank will be inoculated with planktonic microbes and mixed thoroughly to the specified UV Transmission. The pump flow rate will be set and the system primed to remove any air bubbles. The unexposed effluent will then be collected for 10 seconds into sterile bottles. The test product/device will be switched on, and the system primed for at least 10 seconds. Then the exposed effluent will then be collected for 10 seconds into sterile bottles. The microbes from each effluent sample will then be dilution-plated onto nutrient agar and cultured to provide quantifiable viable microbial burden data for each sample collected.
  • Each test will include one microbial strain:
    • Pseudomonas aeruginosa (ATCC 15442) – a standard bacteria
  • Each test will include 24 total data-points:
    • 2 device settings: on & off (as a negative control)
    • 4 flow rates: 1, 2, 3, & 4 Liters per minute.
    • 3 replicate products/devices will be tested for each testing condition (sample size n=3).
  • Note: Optional GLP services are available for an additional fee.
  • Note: Alternate strains can be validated for testing upon request for an additional fee.
  • Note: Optional dosimeter and/or radiometer data collection and analysis are available for an
    additional fee, with pricing dependent on the device(s) requested (please inquire).

Data Analysis

  • Data will be calculated to determine the quantifiable microbial burden in each effluent sample.
  • Data will be analyzed to determine the consistency between replicate samples in each set (n=3).
  • Data will be analyzed to compare the efficacies of each testing condition to determine the percent reductions and log reductions of microbial burdens compared to unexposed samples. 

Turnaround Time

  • 2-4 weeks following receipt of the test materials.