The EPA's monitoring records for the Midwest City public water system (OK1020806) serving Oklahoma County report chromium-6 (hexavalent chromium) detections in surface water supply. Among 56 samples taken from 2014 to 2015, chromium-6 was identified above the reporting level of 0.03 micrograms per liter (µg/L or ppb) in 46 instances; the highest measured concentration was 16.4 µg/L, with a median detected value of 3.505 µg/L. No health-based violations were noted in this system's record by the EPA. It is important to distinguish these system-wide findings from any specific household’s water condition, which requires individualized testing.

Trivalent Versus Hexavalent Chromium: Why Total Chromium Data Can't Tell the Whole Story

Total chromium measurements include all chromium species but do not differentiate between chromium-3 (trivalent chromium) and chromium-6 (hexavalent chromium).

Chromium-3 is an essential nutrient in small amounts, while chromium-6 has different chemical properties and potential health considerations. Since the public water record separates chromium-6 and total chromium data, understanding the proportion of chromium-6 is critical when assessing water quality concerns.

California’s 10 µg/L Chromium-6 Limit and Its Implications for Oklahoma County Residents

California has established a public health goal of 10 micrograms per liter (µg/L) specifically for chromium-6 in drinking water, a regulatory level that does not apply federally. This limit reflects state-level risk assessments but does not represent a legal threshold in Oklahoma or federal mandates.

Midwest City’s monitoring shows chromium-6 levels up to 16.4 µg/L, above California’s guideline but without any associated federal health violations or enforceable limits for chromium-6. Residents outside California should view such guidelines as contextual information rather than direct mandates.

Sample Depth, Source Type, and What to Expect in Household Water Quality

Water quality parameters for chromium-6 can vary according to source types like surface water or groundwater and sampling depth. Midwest City’s system utilizes surface water sources, which may have different chromium profiles compared to wells drawing from aquifers.

Households relying on private wells or different water sources should obtain their own water tests to determine specific chromium-6 presence and levels, as regional public system results do not substitute for individual analysis.

What to Document Before Selecting a Chromium-6 Water Treatment Option

• Have an up-to-date, laboratory-certified chromium-6 test specific to your household water source.
• Note whether your water is from a municipal supply or a private well.
• Record whether your water source is surface or groundwater.
• Be aware of any local water quality reports from your public water system.

Collecting this information ensures informed decisions regarding treatment needs and appropriate technology selection.

Differences Between Aesthetic Secondary Standards and Health-Based Limits for Chromium-6

Aesthetic secondary standards issued by EPA address taste, staining, or odor concerns rather than health risks. These may include recommendations for total dissolved solids or chloride but do not directly apply to chromium-6.

For chromium-6, no federal health-based maximum contaminant level (MCL) currently exists, though total chromium has an MCL of 100 µg/L, which is much higher than observed chromium-6 levels in Midwest City. Therefore, detected chromium-6 concentrations here do not indicate a breach of federal health limits but may influence treatment considerations based on personal preferences or local guidelines.

Summary and Next Steps

The EPA's public water system record for Midwest City in Oklahoma County confirms chromium-6 is detected in surface water at levels varying up to 16.4 micrograms per liter, with no health-based violations reported. These findings apply at the system level and are not definitive for individual household water quality.

Residents considering treatment options should obtain specific chromium-6 water test results for their home and document water source details. A suitable approach to managing chromium-6 includes technologies like the Pentair Chromium-6 Filter, which ships ready to configure for household use and is designed to address chromium-6 presence effectively.

For more information and access to official data, visit the EPA's Unregulated Contaminant Monitoring Rule database, which provides ongoing surveillance of chromium-6 and other constituents in public water systems.

Where this information comes from

Source: EPA SDWIS public water system record. Sampled 2015-08-04. These figures describe the public water system's record, not the plumbing inside any individual building.

On record: EPA UCMR3 monitoring (2013-2015) for Midwest City (OK1020806), OK: 112 results across 2 listed contaminants, 100 detections above the reporting level; no federal MCL for hexavalent chromium; total chromium MCL 100 ug/L