The Maximum Contaminant Level and the Public Water Supply

Water is an effective solvent, so the water from a residential faucet will naturally have trace amounts of different substances. Ionic minerals like calcium and sodium will improve the taste of tap water. Many water systems add fluoride to support dental health in the area. Other contaminants are not beneficial. When a substance has associated health risks, the Clean Water Act empowers the EPA to develop regulations around it. Calculating a maximum contaminant level is an essential step in maintaining the safety of the water supply.

The List of EPA Contaminants

The EPA currently has a list of over 90 contaminants that require regulation. Every year, the agency decides if there are new substances that require drinking water limits. While there are many possible contenders, the EPA chooses new substances based on criteria outlined in the Safe Water Drinking Act.

  • Known Health Risks: Has research shown that the substance has adverse effects on health and well-being.
  • Contamination Risk: Is the substance likely to be present in public water systems?
  • Meaningful Risk Reduction: Will lowering levels of the substance provide significant benefits?

Establishing EPA Regulations on Water

After identifying a substance as a contaminant of concern, researchers work to develop new EPA standards for safe drinking water. This process goes through several stages as the agency learns more about the effects of the contaminant.

MCL Goals

The drinking water limit calculation begins with an MCL goal. This level is a non-enforceable guideline determined by how the substance affects sensitive populations like infants and the elderly. The MCLG will inform water facilities as they look at ways to mitigate new EPA contaminants.

MCL Measurement

Often, the enforceable maximum contaminant level will be higher than the MCLG. The MCL is the standard water systems must meet to comply with clean water regulations. The EPA determines the MCL measurement based on several criteria.

  • Long and Short-Term Health Risks
  • Ease of Measurement
  • Contamination Risk
  • Cost/Benefit Analysis

Once the MCL is in place, the level isn’t necessarily final. It’s subject to review every six years as new information and technologies arise.

MCL Enforcement

Water systems have three years to come into compliance with new EPA standards. The agency can extend this time if measuring and treating the substance require significant changes to water treatment facilities.

If measuring the substance requires techniques or equipment that aren’t feasible for a local water system, the EPA may establish treatment techniques. In this case, water systems must preemptively add the technique as a preventive measure.

Other MCL Sources

The EPA is the primary resource for determining drinking water limits. However, individual states can establish MCLs for their territories. The federal government may also legislate MCLs based on research done outside the EPA.

SCADA and MCL Water Testing

EPA regulations on the water often require additional testing techniques from water facilities. A supervisory control and data acquisition system can simplify this process. SCADA technology uses sensors to provide real-time data to facility staff members. As water flows through the system, these sensors can check current contaminant levels to ensure they are within the acceptable limit.

If MCL water testing reveals levels that are near or above the limit, the system will send an alert to the facility manager. A water treatment plant could also create an automatic response that turns on additional treatment protocols, minimizing the potential service disruption.

A Partner for Cloud-Based SCADA

High Tide Technologies provides cloud-based SCADA technology to municipal water collection, distribution, and treatment facilities. We design adaptable systems that can change as new requirements come online. Our cloud-based model allows facility managers to receive alerts from any location on a handheld device. HTT can help develop responsive, efficient facilities in the water industry. Contact us today for more information.