The water filter manufacturers supply performance data sheets. We take these numbers as given when they are tested and certified by NSF International.
Lead
Lead reduction is tested at two different pH levels; each level has a minimum and average reduction. This information can be represented as a 2x2 matrix. For example, the Brita Pitcher filter's matrix is:
|
pH 8.4 |
pH 6.3 |
| Minimum % |
95.7 |
97.9 |
| Average % |
98 |
99 |
The minimum reduction at pH 8.4 is 95.7% (highlighted), which is the worst case in the matrix. We always use the worst case because that is the minimum reduction you are gaurenteed.
Chlorine
Average and minimum chlorine reduction is stated in the performance data sheets. We use the minimum reduction.
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