is ppb the same as mg/l?
For water, 1 ppm = approximately 1 mg/L (also written as mg/l) of contaminant in water, and 1 ppb = 1 ug/L (also written as ug/l). A measurement of 6 mg/L is the same as 6 ppm or 6,000 ppb, which is equal to 6,000 ug/L.