First-Line Indicators: This section is a dictionary for your water report. Your water quality test results sometimes use scientific terms and numbers. Here, we explain the common words you’ll see and give tips on how to read the water quality table. The glossary provides simple definitions, and the step-by-step guide will help you make sense of the numbers. Our goal is to make sure you feel confident reading your report and knowing what it tells you about your water. The first checks we perform on your water. By themselves, they don’t show if your water is safe, but they help us understand the rest of the results.

Salts: Minerals that dissolve in water. They can leave a white ring or spots on containers, dishes, or faucets after the water dries. This is an aesthetic issue, not a health risk.

Biologicals: Microbes (tiny living things) in your water. We focus on a few key bacteria that best show overall water quality and possible contamination sources. There is a health risk if harmful bacteria are present.

Metals: Metals occur naturally in water or can be there due to contamination. Some (such as iron or copper) are not harmful and can even be good for you in small amounts; others (such as lead and arsenic) cause health problems over time. Metals can also affect taste. There may be a potential health risk depending on the type and amount of metals.

MPN (Most Probable Number): A way to estimate how many microbes (tiny living things) are in a set amount of water (usually 100 mL, about 3 ounces).

Desirable Range: The level scientists and health experts consider safe to drink for many years. Results inside this range are preferred.

mg/L (milligrams per liter): A tiny amount of something. It is a unit used to measure small amounts of other substances in the water. One milligram is 1/1,000 of a gram (1 mg/L means 1 milligram in 1 liter of water). Parameter: Anything that can be measured and reported in your water, such as salts, particles, or bacteria.

EPA (Environmental Protection Agency): The U.S. government agency that sets the national rules for safe drinking water. The EPA sets standards, such as the maximum levels of certain chemicals or the number of germs allowed in tap water, to help protect people’s health.

CDC (Centers for Disease Control and Prevention): The U.S. public health agency that studies and tracks illnesses. The CDC provides information on how water quality can affect health and guidance to prevent illness from unsafe water.

WHO (World Health Organization): An international health agency that works with countries around the world to protect public health. The WHO sets global guidelines for safe drinking water and helps communities reduce health risks from contaminated water.