Government records from U.S. Geological Survey sampling of groundwater in Westchester County's aquifer 111FILL show copper was detected in 32 out of 33 wells sampled between 2012 and 2015, with concentrations ranging from 1.2 to 694.0 micrograms per liter and a median of 20.6 micrograms per liter. None of these results exceeded federal thresholds.

Understanding Certified Lab Test Reports for Copper

Test Results Express Concentrations in Micrograms per Liter (L/L)

A certified laboratory test for copper in household water will show numeric concentration values, often in micrograms per liter (L/L). This reports the copper amount dissolved or suspended in the water sample. It is important to note that such numbers reflect that specific sample only, not necessarily your well or tap water at all times.

Detection Does Not Imply a Violation or Safety Issue

Detection means the instrument measured copper at or above the test's reporting limit. It is not synonymous with a legal or health violation. In Westchester County, no sampled wells exceeded federal copper limits, indicating no established health-based violation from the regional data.

Seasonal and Multi-Year Variation in Copper Levels

Samples Collected Across Nearly Three Years Reflect Temporal Changes

The 33 samples span from late 2012 to late 2015, capturing possible annual and seasonal variations. Copper levels ranged broadly, suggesting fluctuations may occur over time and between wells.

Range Indicates Some Wells Show Higher Copper Than Others

With values from 1.2 to 694.0 L/L, the data reveal significant variability likely influenced by local geology, well depth (30-122 feet sampled), and other environmental factors.

Distinguishing Aesthetic Secondary Standards From Health-Based Limits

Secondary Standards Relate to Staining and Taste, Not Safety

Standards addressing aesthetic concerns such as copper staining focus on taste, color, or fixture discoloration. These secondary standards do not define health hazards.

Federal Health-Based Copper Limits Are Not Exceeded in These Samples

The Westchester County regional sample set did not exceed health-based federal copper limits, underscoring that observed copper concentrations are not a safety violation.

Differences Between Public Water Records and Private Well Testing

Public System Records Reflect Distribution Water, Not Source Wells

Municipal water records report on treatment and distribution systems, which can differ in copper levels from raw groundwater sampled in this regional study.

Private Well Water Requires Specific Testing To Know Copper Levels

To understand copper in your household water, testing your own well or tap water through a certified lab is necessary; regional data cannot confirm your private water conditions.

Comparing Westchester County Copper Data to Neighboring Counties

Regional Differences Can Exist Based on Aquifer and Geology

Neighboring counties may have different copper ranges and medians; comparisons should acknowledge geological and hydrological distinctions.

Avoid Inferring Individual Well Water Quality from Regional Data

Regional medians and ranges are meant to set expectations but do not predict exact copper concentrations in any one household supply.

Distinguishing Copper Stains From Other Common Household Water Issues

Copper Staining Is Visibly Different From Iron or Manganese Staining

Copper stains typically appear as blue-green discoloration, distinct from reddish-brown or black stains caused by iron or manganese.

Water Chemistry and Plumbing Materials Affect Stain Formation

Age and composition of pipes, water pH, and dissolved solids interplay with copper presence to influence stain occurrence.

It is important not to conclude that the regional copper data represent your own household's water quality. Confirm your water conditions with certified laboratory testing before considering treatment options. If copper staining is evident and testing confirms elevated copper, the C-Series Blue-Green Copper Stains Filter ships ready to configure to address this issue effectively in residential water supplies.

Where this information comes from

Source: USGS groundwater sampling. Sampled 2015-11-19. These figures describe groundwater sampled in this area. They are not a test of any individual private well - only a test of that well can establish its own water.

On record: U.S. Geological Survey sampling of Copper in the 111FILL aquifer (Westchester County): 33 results from 31 wells, median 20.6 ug/L, range 1.2-694.0 ug/L; none above any federal threshold