On average, the cost per sample can range anywhere from $3.01-$3.68 per sample. The cost per sample varies depending on the COD/BOD range and the number of samples analyzed, as this affects consumable usage such as calibrant, electrolyte and sensors. In general, the cost per sample decreases with an increase in the number of samples. There are several reasons for this, one being that the sensor should be replace monthly, therefore running more samples per month will yield a better return on sensor usage. In addition, the PeCOD requires a daily calibration; by running more samples per calibration users save on consumable costs associated with calibrant. There are no disposal costs for the PeCOD, whereas disposal costs accumulate via the traditional dichromate method with every sample vial.