Why do the log reduction levels differ for varying Berkey® element tests? Some laboratory results show testing to greater Log reduction (example: 99.9% vs. 99.99999%) than others.

“…The quantitation limit of an individual analytical procedure is the lowest amount ofanalytein a sample which can be quantitatively determined with suitable precision and accuracy. The quantitation limit is a parameter of quantitative assays for low levels of compounds in sample matrices, and is used particularly for the determination of impurities and/or degradation products…” 


Quantitation Limit

The reduction level chosen is the lowest amount of potential contaminants in a sample that can be accurately determined, given the laboratory test equipment available. This value is determined following EPA protocols and verified by an annual EPA audit.

Various laboratories offer different log reduction levels for which they can test. Typically, the higher the log level of testing, the higher the cost per contaminate. In other words, testing to Log 4 reduction levels costs much more than testing for Log 3, etc. It is a function of cost vs what log levels are necessary for customers to determine the effectiveness of our elements in removing a broad range of contaminants.

For example, it may cost the same amount to test 200 contaminants at Log 3 (99.9%) reduction, 20 contaminants at Log 4, or two contaminants at log 5. The feedback from our customers indicates that most of them would prefer testing on a broader range of contaminants tested at 99.9% reduction than a much narrower list of contaminants tested at a higher log. In general, 99.9% reduction is sufficient for static contaminants such as chemicals and heavy metals whereas dynamic contaminants, such as biological contaminants, which can multiply, require greater precision testing (higher log reduction).

The reduction level achieved can fall above the detection limit or below the detection limit. Either way, the actual reduction levels reported are calculated using the quantitation limit, which provides the percentage reduction levels reported by the individual laboratory. It is important to note that >99.9% reduction denotes that the actual reduction levels are “greater than” 99.9%”, which exceeds the maximum log testing target and implies a greater log reduction is taking place than that which is being reported.

Moreover, the human body is a remarkable piece of engineering capable of effectively eliminating many varieties of contaminants. The purpose of water purification it to prevent the body from becoming overwhelmed with such high levels of toxins that the body can no longer effectively eliminate them. It is NMCL’s goal to provide purification and filtration systems that are able to remove and reduce as many toxic contaminants as is possible without removing the healthful and beneficial minerals that your body needs.