Measurement is within the interquartile range (IQR), defined as the 25th to 75th percentile or middle half (50%) of the measurements. Examples: sulfate, ammonium, sodium, and potassium.
Measurement is within the range defined by the median + IQR/1.349. The ratio, IQR/1.349, is the non-parametric estimate of the standard deviation, sometimes called the pseudo-standard deviation. Examples: nitrate, chloride, and calcium.
Measurement is outside the range defined by the median + IQR/1.349. Examples: pH, conductivity, and magnesium.
Measurement is below the detection limit of the laboratory’s analytical method. Example: fluoride.
Measurement | DQO (before January 2018) | DQO (effective January 2018) |
---|---|---|
pH < 4.00 | + 0.07 units | + 0.05 units |
pH: 4.00 - 4.99 | + 0.07 units | + 0.07 units |
pH > 5.00 | + 0.07 units | + 0.10 units |
conductivity | + 7% | + 7% |
acidity | + 25% | + 25% |
sulfate | + 7% | + 5% |
nitrate | + 7% | + 5% |
ammonium | + 7% | + 7% |
fluoride | none | + 20% |
chloride | + 10% | + 10% |
sodium | + 10% | + 10% |
potassium | + 20% | + 20% |
calcium | + 15% | + 15% |
magnesium | + 10% | + 10% |