How to Use This Guide

Many New Mexico residents rely on private wells for their drinking water. Unlike public water systems, private wells are not regulated in New Mexico or in most other U.S. states. This means there are no enforceable drinking water standards that apply to private well water, and well owners are responsible for deciding whether their water is safe to use.

This guide is intended to help people who rely on private wells interpret laboratory test results by providing health-based reference values, brief explanations of potential health effects, and information about who may be most at risk. The goal is not to tell people what they must do, but to give them the information needed to make informed decisions about drinking, cooking, and household water use.

What the numbers in this guide mean

For contaminants that do not have a federal MCL, this guide may also include:

• Health-based limits or guidance values from other U.S. states
• Health-based standards or guideline values from other countries
• Lifetime health advisories or other non-enforceable reference values

These additional values are included for informational purposes only. They do not apply to public water systems in New Mexico and are not legally enforceable. They are provided so private well users can better understand how their test results compare to health-based values used elsewhere and decide what level of protection they are comfortable with for themselves and their families.

Note: Health-based reference values are typically set well below levels where health effects are expected to occur and are intended to be protective over a lifetime of exposure. A result below a listed value does not necessarily mean zero risk, and a result above a value does not necessarily mean that health effects will occur. These values are tools to help interpret results, not precise thresholds between "safe" and "unsafe."

How this guide is intended to be used

This guide is designed to be used alongside your private well water test results:

• Compare your test results to the health-based reference values listed.
• Review the brief descriptions of potential acute and long-term health effects.
• Pay special attention to contaminants that identify infants, children, pregnant women, or people with certain health conditions as being most at risk.
• Use this information to decide whether to continue using the water as is, seek additional testing, install treatment, or consult a health or water professional.

Summary of Water Analytes

The table below summarizes common water analytes, associated health-based reference values, and potential health effects relevant to drinking water.