If you see perchlorate mentioned, but no detected levels above 4.0 µg/L, what does this mean?
Many homeowners worry upon hearing about perchlorate presence in water sources. However, Clackamas County’s public water system record for Wilsonville, City of (OR4100954) shows 18 samples taken from 2002 to 2003 with no perchlorate detected above the reporting level of 4.0 micrograms per liter (µg/L). This indicates the instrument detected perchlorate below this threshold or not at all. Importantly, federal regulations have not set a maximum contaminant level (MCL) for perchlorate yet, so these detections or non-detections are measurements, not violations or safety conclusions.
If you want to understand why aesthetic secondary standards differ from health-based limits for perchlorate
Aesthetic secondary standards focus on taste, odor, color, or staining that might affect water quality perception but are not health safety levels. Perchlorate lacks an aesthetic secondary standard because it does not impact these qualities. Instead, health-based limits would address health risks, but since perchlorate currently has no federal MCL, regulatory authorities rely on voluntary monitoring and research to evaluate any potential health concerns. For Wilsonville’s system, EPA records show no health-based violations related to perchlorate during the monitoring period.
If you observe variation in perchlorate results over time in public records
The 18 samples for perchlorate in Wilsonville were collected between July 25, 2002, and November 4, 2003. Although no perchlorate was detected above 4.0 µg/L in any sample, this timeline illustrates how monitoring spans more than a year to identify any seasonal or multi-year fluctuations. The lack of detections above the reporting level during various seasons and conditions suggests a consistent low perchlorate presence in the public water system’s surface water source.
If you want to compare Clackamas County perchlorate monitoring data with neighbouring counties without overreading it
Comparisons between counties require careful context. For example, a neighbouring county might show detections at or below the reporting level for perchlorate, similar to Wilsonville’s public system. Since no federal MCL exists and detections below reporting levels do not signify violations, one cannot conclude one county’s water is safer or more problematic solely based on these findings. Differences in water sources, sampling frequency, and measurement techniques all influence results and their interpretation.
If you wonder how public water system records differ from private well testing in what they establish
Public water system data, like Wilsonville’s, represents overall conditions affecting thousands of connections and serves 25,915 people. These records reflect average or range measurements from the system’s source and treatment points but do not specify individual household water quality. Private wells vary greatly by location and depth and require individual laboratory testing to establish perchlorate levels accurately. Public system monitoring does not replace or predict the outcome of private well testing for a household.
If you want to understand what a certified laboratory test for perchlorate reports and how to read it
A certified lab test for perchlorate measures the specific concentration in your household water sample. Results below the laboratory reporting level (for example, 4.0 µg/L) mean perchlorate was either absent or present at very low levels not quantifiable by the method used. Any detection is simply a measurement, not a violation or indication of safety or risk. Compare your lab’s result to the EPA’s published data for the local public system to understand relative levels but remember your household’s water may differ.
If you consider how many samples and wells stand behind Clackamas perchlorate figures and what a small sample means
The EPA’s record for Wilsonville includes 18 perchlorate samples collected over roughly 15 months from the public water system serving 7,187 connections. This number of samples provides a baseline understanding, but it is not exhaustive of all conditions or changes since 2003. A small sample size means there may still be local variations or shifts over time not captured in that dataset. Ongoing monitoring and individual water testing help capture any changes for your household water quality profile.
For households concerned about perchlorate, the C-Series Perchlorate Filter ships ready to configure and offers documented technology designed to reduce perchlorate if testing shows elevated levels in your water. Confirm your own water’s perchlorate concentration with certified laboratory testing, then consider this filter system to suit your household’s demand and water quality needs.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2003-11-04. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR1 monitoring (2001-2005) for WILSONVILLE, CITY OF (OR4100954), OR: 18 results across 1 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level