Understanding Water Quality Standards: PHGs vs. MCLs

-Zach Greenfield

Introduction

At Greenfield Water Solutions, we understand that many of our customers prioritize the highest standards of water quality. We frequently receive questions about Public Health Goals (PHGs), also known as health guideline levels (HGLs), and how our filters measure up. Here, we aim to clarify the difference between PHGs/HGLs and Maximum Contaminant Levels (MCLs) and explain why most filters, including reverse osmosis (RO) systems, ultrafiltration, and distillation, typically adhere to MCL standards.

What Are Public Health Goals (PHGs) or Health Guideline Levels (HGLs)?

Public Health Goals (PHGs), also known as health guideline levels (HGLs), are set by the Office of Environmental Health Hazard Assessment (OEHHA). When calculating a PHG/HGL, OEHHA considers all available information to identify the level of a chemical in drinking water that would not cause significant adverse health effects in people who drink that water every day for 70 years. For cancer-causing chemicals, the PHG/HGL is typically established at the “one-in-one-million” risk level, meaning that not more than one person in a population of one million people drinking the water daily for 70 years would be expected to develop cancer as a result of exposure to that chemical.

PHGs/HGLs are not regulatory standards but serve as aspirational targets that indicate the level of contaminants at which no adverse health effects are expected. They provide a framework for understanding health risks and guide the improvement of drinking water quality.

What Are Maximum Contaminant Levels (MCLs)?

MCLs are enforceable standards set by the Environmental Protection Agency (EPA) under the Safe Drinking Water Act. These standards represent the highest level of a contaminant that is allowed in drinking water. MCLs are set as close to the PHGs/HGLs as feasible, considering available technology, treatment capabilities, and cost.

MCLs balance the ideal health outcomes represented by PHGs/HGLs with practical considerations such as technological feasibility and cost. While MCLs might not achieve the near-zero contaminant levels of PHGs/HGLs, they are set at levels that ensure safety and public health, providing a realistic and enforceable standard.

Why Do Filters Adhere to MCLs?

While PHGs/HGLs represent ideal conditions, achieving these levels with current technology is often not feasible. Most water filters, including high-quality reverse osmosis (RO) systems, ultrafiltration, and distillation, are designed to meet MCL standards, which are realistic and attainable benchmarks ensuring safe drinking water.

Achieving PHG/HGL levels with current filtration technologies is challenging. Most commercially available filters can significantly reduce contaminant levels but often fall short of PHG/HGL targets due to the limitations of available technology. Achieving and maintaining PHG/HGL levels would require frequent filter changes, advanced technologies, and higher costs, making it impractical for most households.

Addressing Customer Concerns

One challenge we face is that some customers use PHGs/HGLs as the standard for evaluating water treatment efficacy. It is important to understand that PHGs/HGLs were never intended to be the sole determinant of a filter’s effectiveness. Instead, they are meant to inform and guide improvements in water quality.

We understand that our customers want the cleanest water possible, and while it’s challenging to achieve PHG/HGL levels, our filters aim to get as close as possible to these standards. By adhering to MCLs, we ensure that the water is safe and clean, meeting the stringent requirements set by regulatory bodies.

Using EWG.org’s Tap Water Database as a Reference

We recommend using resources like EWG.org’s Tap Water Database. Customers can visit this site to learn what is in their municipal water (not well water). Visit the EWG Tap Water Database for more detailed information.

Conclusion

At Greenfield Water Solutions, we strive to provide the highest quality water filtration systems that meet or exceed MCL standards. While PHGs/HGLs are valuable for understanding potential health risks, MCLs offer a practical and achievable benchmark for ensuring safe drinking water. We are committed to continuous improvement and are always here to address your concerns and provide the best solutions for your water quality needs.