Autotrol Perchlorate Filter

Buy Now

View full details

Understanding What 'Detected', 'Median', and 'Range' Mean in EPA Sampling Records

When EPA reports on perchlorate in the WATER AND POWER AUTHORITY public water system serving VI, it uses terms that can be confusing. A 'detected' value means perchlorate was measured above the method's reporting level of 4.0 micrograms per liter (µg/L). In this system’s 2002 monitoring, every one of the 16 samples tested below that reporting threshold, meaning no perchlorate was detected above 4.0 µg/L. The record also shows zero health-based violations for perchlorate.

The terms 'median' and 'range' describe the distribution of sample measurements across the system. Because no perchlorate was detected above the reporting level in any sample, the median value would be reported as below 4.0 µg/L, and the range does not extend beyond that limit. This does not indicate unsafe water; it reflects that perchlorate concentrations were consistently not measurable above this reporting cutoff during the monitoring period.

A Worked Example: How a VI Homeowner Might Interpret These Data

If you receive water supplied by the WATER AND POWER AUTHORITY in VI, understand these facts:

• Out of 16 federal monitoring samples taken in 2002, perchlorate was not detected above 4.0 µg/L in any.
• The EPA has no health-based maximum contaminant level (MCL) established for perchlorate, so there is no legal violation or health limit exceeded.
• Failure to detect perchlorate at concentrations above the reporting level means perchlorate is either absent or present at very low levels during that timeframe.

Without knowing your specific home's water, these findings mean the water system’s perchlorate levels were below the detection capability of EPA’s monitoring but do not guarantee your well or tap has no perchlorate. A certified laboratory test for perchlorate concentration in your household water is the only way to know your own water’s perchlorate status.

What Distinguishes Perchlorate from Two Commonly Confused Water Concerns

Perchlorate is a chemical that can enter water supplies primarily through environmental contamination from industrial use, but it is distinct from other water quality issues such as nitrate or chlorides which often affect taste or cause staining. Unlike nitrate, which can have a health-based MCL, perchlorate currently lacks a federal regulatory limit and is monitored as an unregulated contaminant.

Perchlorate does not cause the typical odors or metallic tastes associated with some other chemicals and does not contribute directly to hardness or corrosion in household piping. This differentiates it from other constituents that may be confused with it and require different treatment approaches.

How Larger Households, Secondary Homes, or Seasonal Properties Should Consider This Data

Water consumption patterns vary with household size and usage schedule. A larger household or a secondary residence with intermittent use may influence how treatment solutions are chosen if perchlorate is present. Because EPA records for the WATER AND POWER AUTHORITY system show no detections above the reporting level, the prevalence of perchlorate at a concentration requiring treatment is unlikely but not impossible.

Should testing of your water reveal perchlorate at measurable levels, treatment capacity must accommodate the household’s daily water demand. This means selecting equipment that can reliably remove perchlorate at the flow rates and volumes your household uses.

Influence of Sample Depth, Well Depth, and Water Source Type on Perchlorate Expectations

EPA’s monitoring data reflect system-wide sampling rather than individual points such as a specific well or tap. Depth of a water source and type (surface or groundwater) can influence perchlorate presence. Groundwater wells closer to contamination sources may show different results than surface water or deep wells.

Because the WATER AND POWER AUTHORITY’s record shows no perchlorate detections above 4.0 µg/L, it is likely that source water for this public system generally has low perchlorate. However, homeowners using private wells or other sources should test their own water directly to confirm perchlorate levels because local variation can occur.

Ordering a Perchlorate Water Test and Next Steps to Address Your Household’s Water Quality

The crucial step for any homeowner in VI wanting clarity about perchlorate is to order a certified laboratory perchlorate test on their specific household water. This test will report perchlorate concentration precisely, enabling informed decisions about treatment needs.

If perchlorate is detected at levels of concern for your household, the Autotrol Perchlorate Filter is a documented system that ships ready to configure for residential use. It uses proven technology to reduce perchlorate and provides a targeted approach to address this constituent specifically.

Understanding both the regional EPA data and your own home's water test results ensures you can take measured, reliable steps toward maintaining the quality of your household water supply.

Where this information comes from

Source: EPA SDWIS public water system record. Sampled 2002-12-16. These figures describe the public water system's record, not the plumbing inside any individual building.

On record: EPA UCMR1 monitoring (2001-2005) for WATER AND POWER AUTHORITY (VI0000097), VI: 16 results across 1 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level