New Lab Test DataOctober 10, 2021
By Dave Conklin on 10/4/21
In 2019 we sent away an early prototype water box to an overseas lab for a microbiological challenge test. The report from the lab is available on our website.
The results were very positive: a “5-log” reduction in the test organism, i.e. a reduction of 99.999%.
In August this year we submitted a current production water box to an Oregon lab for a new microbiological challenge test. The initial results were disappointing: only a 1.7-log reduction with external power, and a mere 0.3-log reduction with hand-cranking. Because the new lab results were so different from 2019 results, we contacted both labs to get more details about how they had conducted the tests. Paul Berg visited the Oregon lab, Umpqua Research, in person to review their procedures. We reviewed the test specifications that we had provided to the labs. We looked at the differences in construction between the 2019 early prototype unit and the 2021 unit from the second production run. In the end we had the Oregon lab do another test with revised specifications and using a UV bulb from the same source as the one in the 2019 test. Last month we received the results of the second test by the lab in Oregon, and they are more positive: a 2.3-log reduction using external power, and a 1.5-log reduction with hand cranking.
The latest test results from Umpqua Research support estimates of the log reduction in the activity of various pathogens in the table below, when the water box is operated for 60 seconds with external power. Further testing of hand-cranked operation is still in progress. While that testing is being conducted, we are recommending that treatment with hand-cranking be done for 90 seconds rather than 60 seconds.
The estimates in the table are inferences based on a lab test result of a 2.3-log reduction of the MS-2 coliphage using external power. The lab used strain ATCC 15597-B1 of MS-2 in their tests. Based on a guidance document of the International Ultraviolet Association (“Fluence (UV Dose) Required to Achieve Incremental Log Inactivation of Bacteria, Protozoa, Viruses and Algae”), we believe that the water box delivers an average fluence of at least 30 millijoules per square centimeter, when used with external power for 60 seconds. Using the data for the various pathogens in that same guidance document, we worked out lower bounds for the removal percentages given a UV dose of 30 mJ/cm2.
We are continuing a series of tests to characterize the efficacy of the water box in more detail. There is another microbiological challenge test in progress now at the Oregon lab. In addition, we are outfitting one of our water boxes with special quartz windows in the bottom of the tank, to allow us to measure the UV intensity directly from outside the tank itself, after the UV light has passed through the water in the tank.
The reports from the Oregon lab are available at
New test reports will be made available here on this website when we receive them; copies of the lab reports may also be obtained directly by sending an email request to firstname.lastname@example.org.