The EPA’s public water system record for Westerly Water Department, serving Washington County, Rhode Island, shows no perchlorate detected above the reporting level in the groundwater supply. Data from the 2001-2005 federal survey, covering 20 samples, found zero measurements above 4.0 µg/L perchlorate, with no federal maximum contaminant level established for this constituent.
How Public-System Records Differ from Private-Well Testing
The Scope of Public Water System Data
Public water system results represent combined data for an entire distribution network serving thousands of customers, such as Westerly’s system with over 14,800 connections. These data indicate conditions of the source water before it reaches individual homes but do not specify individual household water quality.
Limitations of Applying System Data to a Single Residence
Since local plumbing and private well characteristics can vary, private homeowners should conduct specific water testing to understand their own water’s perchlorate concentration rather than assume the system average applies directly.
How Perchlorate Differs from Other Commonly Confused Water Issues
Perchlorate is a Unique Constituent
Unlike common secondary concerns such as chloride or total dissolved solids, perchlorate is a chemical of interest for potential health effects but is not regulated by a federal maximum contaminant level. Its detection does not mean contamination or violation.
Not Associated with Taste, Staining, or Corrosivity
Perchlorate is not responsible for aesthetic water issues like corrosion or discoloration, setting it apart from constituents governed by secondary standards.
How Sample Depth, Well Depth, or Source Type Affect Expectations
Groundwater as the Source for Westerly
Westerly’s water system is supplied by groundwater, typically deeper and less exposed to surface contaminants compared to surface water sources. This contributes to the non-detection of perchlorate in the samples.
Variability Based on Well Construction and Depth
Individual wells may vary significantly in depth and location, influencing the likelihood and level of perchlorate detection when sampled directly.
Definitions: Detected, Median, and Range in the Sampling Record
Detection Level Explained
Detection refers to whether perchlorate was measured above the reporting level, which here is 4.0 micrograms per liter (µg/L). No samples from Westerly exceeded this threshold.
Median and Range
The median would represent the middle value of detected concentrations across samples, while range would show the spread between lowest and highest values detected. With no detects above the reporting level, these data are effectively zero in this instance.
Why Aesthetic Secondary Standards Differ from Health-Based Limits
Secondary Standards Address Appearance and Taste
Secondary standards manage water qualities like color, odor, and stains, which perchlorate does not influence. These standards do not imply health risk or necessitate treatment for perchlorate concerns.
Health-Based Limits Are Still Under Study
Since no federal maximum contaminant level exists for perchlorate, regulatory focus remains on monitoring and research rather than enforced limits. Homeowners concerned about perchlorate may consider testing their specific water to guide treatment decisions.
In summary, Westerly’s public water system record shows no perchlorate detections above reporting levels, providing reassurance about the source water’s quality. Those choosing water treatment equipment for perchlorate concerns in their household should first test their individual water supply and consider solutions such as the Pentair Perchlorate Filter, which ships ready to configure and addresses perchlorate effectively when present.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2003-07-31. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR1 monitoring (2001-2005) for WESTERLY WATER DEPARTMENT (RI1559512), RI: 20 results across 1 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level
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