Key Informant Interviews

William Cottrell

• Key Insights Gained:
  • Municipal water treatment facilities commonly use chlorine to disinfect the water that is distributed as tap water
  • Free Chlorine Residual is the chlorine available for disinfection of water after the chlorine load has been met. Free Chlorine Level is the commonly used term for testing for this value
  • The Free Chlorine Level in drinking water has to be above 0.2 mg/L in order to sufficiently neutralize infectious pathogens, but below 4.0 mg/L in order to not exceed the level that is safe for a human to consume in a lifetime
  • The water is tested when leaving the treatment plant and the Free Chlorine Level must be above 0.2 mg/L, and there should be trace all throughout the distribution system
  • The WHO recommends keeping the Free Chlorine Level below 2 mg/L to prevent issues with tasting the chlorine
  • Hach company colorimeters and spectrophotometers, as well as those made by many other companies are used in municipal water treatment facilities in order to ensure Free Chlorine Level is above 0.2 mg/L
  • Ascorbic acid (Vitamin C) is used as a dechlorinating agent when the FCR is above 4 mg/L, because the reaction forms nonharmful byproducts
  • Testing for quality assurance for some things occurs as often as hourly at times, and as infrequently as every 5 years for other things
  • Testing is always scheduled well in advance at every level (local, state, federal)

Contract Lab Services Aggregate (4 representatives interviewed)

• Key Insights Gained:
  • Ultraviolet/Visible Light Spectrophotometry can be used in order to detect Free/Total Chlorine, and glucose concentrations, and would be an efficient and accurate method to use for detection of these things in water.
  • Induced Coupled Plasma Mass Spectroscopy can be used to detect sodium and potassium concentrations efficiently and accurately
  • Ion Chromatography can be used to detect chloride and citrate efficiently and accurately
  • Chlorite is likely converted to chloride by reactions with citrate in solution

Dr. Yuangen Yang

University of Georgia Feed & Environmental Water Lab

We approached The University of Georgia Feed and Environmental Lab fter finding that they were an EPA certified facility for testing water samples for microbes. This is a way we envisioned analyzing our water samples if the “at-home” sampling kits were not specific enough. We had various questions, and gained lots of great information.

• Key Insights:
  • Total Coliform counts is the method the lab would use to analyze the samples for bacteria. The results are highly specific, and further analysis using NExt Gen Sequencing wouldn’t be necessary to quantify bacterial load Distinguishing the type of coliform count is important
  • Total coliforms include bacteria that are found in the soil, in water that has been influenced by surface water, and in human or animal waste
  • Fecal coliforms are the group of the total coliforms that are considered to be present specifically in the gut and feces of warm-blooded animals. Fecal coliforms are considered a more accurate indication of animal or human waste than the total coliforms
  • Escherichia coli (E. coli) is the major species in the fecal coliform group, because it is generally not found growing and reproducing in the environment like other species. Consequently, E. coli is considered to be the species of coliform bacteria that is the best indicator of fecal pollution and the possible presence of pathogens
  • This lab would use an E. coli coliform count, as opposed to a total coliform count that you would find in standard at home kits. This would give us the best indication, but with more cost associated
  • As for analyzing Protozoa and Viral particles in the samples, this lab said that it is not something they generally do as it requires an extraction, followed by qPCR and sequencing
  • More information on Viral and Protozoa determination can be found here