HGL

The Health Guidance Level (HGL) is a health protective drinking water benchmark compiled by SimpleLab to help make lab results easier to interpret. The HGL is determined by selecting the lowest, and therefore, most protective human health benchmark available from public health agencies for a contaminant. It represents the concentration above which there may be a potential risk to human health if the water is consumed over a lifetime. Some of the benchmarks that the HGL is derived from include Federal Maximum Contaminant Level Goals (MCLG) and California's Public Health Goals (PHG). Drinking water at or near the HGL over the course of your lifetime is thought to be safe and protective of your health.
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When the Report shows "No HGL Available", it means that there is not enough data or research in the scientific literature to support establishing a recommended maximum.

Federal MCL

The federal maximum contaminant level (MCL) is an enforceable primary drinking water standard set by the U.S. EPA. MCLs are the highest concentration of a contaminant permitted in drinking water from public water systems under the Safe Water Drinking Act. MCLs are set as close as possible to health protective levels, while also taking into account the cost and availability of treatment technologies.

Federal MCLG

The federal level maximum contaminant level goal (MCLG) is a non-enforceable public health objective. MCLGs are set to zero for known carcinogens, or a lifetime no-effects level for non-cancer endpoints, assuming that you drink the tap water for 70 years. This is considered a minimum risk level that is protective of your health.

MDL

The method detection limit (MDL) is the lowest value at which a laboratory is confident it can detect a contaminant.

LOQ

The limit of quantification is the concentration at which the laboratory is confident enough to accurately quantify the concentration of a detected contaminant.

PPM

The parts per million (PPM) notation is used to convey a ratio of mass to volume of a concentration in water. It stands for one part of contaminant by mass to one million parts water by volume. Based on the density of water, we know that 1PPM is equivalent to a mass-to-volume ratio of 1 mg/L. Therefore if you have 10 PPM of nitrate in your water, you have 10 mg/L of nitrate in your water.

PPB

The parts per billion (PPB) notation is used to convey a ratio of mass to volume of a concentration in water. It stands for one part of contaminant by mass to one billion parts water by volume. Based on the density of water, we know that 1PPB is equivalent to a mass-to-volume ratio of 1 ug/L. Therefore if you have 10 PPB of nitrate in your water, you have 10 ug/L of nitrate in your water.

PPT

The parts per trillion (PPT) notation is used to convey a ratio of mass to volume of a concentration in water. It stands for one part of contaminant by mass to one trillion parts water by volume. Based on the density of water, we know that 1PPT is equivalent to a mass-to-volume ratio of 1 ng/L. Therefore if you have 10 PPT of nitrate in your water, you have 10 ng/L of nitrate in your water.

pCi/L

Radiological compounds are frequently measured as the ratio of radioactive decay per unit volume. Picocuries per liter (pCi/L) is a standard unit. A picocurie (pCi) is the rate of radioactive decay of a radioactive element. One pCi is one trillionth of a Curie, or 0.037 disintegrations per second.

CFU/mL

Bacterias grow in colonies. As such, a common measure of bacteria in drinking water is to measure the number of colony forming units (CFU) per milliliter (mL) of water. CFU/mL therefore measures the concentration of viable bacterial (or fungal) cells in water.

Present/Absent

Present/Absent is a binary way of reporting the presence or absence of bacteria, fungi, or any contaminant that does not get quantified at the lab. If a contaminant is “present”, it has been detected in water, but not quantified. If a contaminant is “absent”, it was not detected in water.

Non-detect

Non-detect is short for non-detection, or not detected. This phrase is used to indicate that the laboratory tested for a contaminant, but it was not detected above the detection limit. A non-detect does not mean that the contaminant concentration is zero–but rather that, given laboratory methods and analytical instrument capacities, the contaminant was not seen above a very low concentration (the detection limit).