INITIAL LESSONS FROM THE FIELD TRIALFebruary 09, 2022
By Dave Conklin
DayZero Products and the Water Box Volunteers group are working together to field test and improve the water box. During the last several months, we have conducted and documented an analysis of water box performance relative to World Health Organization criteria, we have developed a mathematical model of the spatial variability of the UV dose throughout the volume of the water box, and we have commissioned four rounds of lab testing. Details of these efforts are available on request.
In an update to the dayzerointernational.org website to be made this month, there is a list of what has been learned so far from the ongoing water box field trial in Uganda:
- For 1 minute illumination, hand-cranked operation delivers only about 70% of the UV dose delivered by operation using external power.
- UV intensity varies by about one-third from manufacturer to manufacturer. We have standardized on bulbs from the best manufacturer.
- The bulbs require more than one minute to reach full intensity. We have increased the illumination time using external power to 2 minutes.
- We have a >10% early failure rate on timer circuits.
- With the current design operated for 2 minutes using external power, we now expect the water box to perform well enough to qualify for the World Health Organization’s 2-star rating, but probably not well enough to qualify for the WHO’s 3-star rating.
- Most households in the Ugandan district selected for the field test have electrical service. Water boxes supplied to the test households have been modified to require external power.
The Water Box Volunteers group is organizing and funding the field trial in Uganda. The group met last month and made a decision to postpone deployment of water boxes to test households until we can demonstrate performance which would merit a 2-star rating from the World Health Organization. A fourth round of testing at a U.S. lab is underway now. We have concluded, from the lab tests performed in 2021 in the U.S. lab and other analysis, that the initial lab test results in 2019 from an overseas lab are not trustworthy.
Water boxes for the field trial have been modified to require external power and to increase the illumination time to 2 minutes. Eventually, DayZero Products will make retrofits available for U.S. water box customers, based on final results from the field trial in Uganda and from further testing of hand-cranked operation here in the U.S. I expect that we may add a reflector to improve hand-cranked performance, but there is more work still to do before a decision can be made.