What is the difference between micrograms (μg/L) and milligrams (mg/L)? Microgram per liter (μg/L) is a unit of concentration that measures the amount of a substance dissolved in a given volume of water (1 liter). A microgram is equivalent to one millionth of a gram. 1000 micrograms is equivalent to 1 milligram (mg), so 1 mg/L is equal to 1000 μg/L.
What is the difference between micrograms (μg) and ppb (parts per billion)? They are basically the same. Micrograms per liter (μg/L) are sometimes referred to as ppb (parts per billion) in aqueous solutions because there are 1 billion micrograms in 1 liter.
What does MCLG and MCL mean? Maximum contaminant level goal (MCLG) is the level of a contaminant in drinking water below any known or expected risk to health. MCLGs allow for a margin of safety and are not enforceable standards. Maximum contaminant level (MCL) is the highest level of a contaminant that is allowed in drinking water. MCLs are enforceable standards.
What happens if the water tests over the MCL from the EPA? If the water tests over the MCL (maximum contaminant level), this triggers regulatory action based on the Safe Drinking Water Act. In general, the water supplier must consistently test water. If a contaminant is consistently present, the water supplier must take steps to reduce the amount of the contaminant so that it is consistently below that level. MCLs require monitoring, remediation, and public notice when standards are exceeded.