Interpreting the Median and Range of Water Quality Data: What Tacoma Water Division’s Record Shows
When examining Pierce County’s primary water supplier, the Tacoma Water Division, it is important to note their source water is surface water. Public system records from federal EPA databases list various measured parameters for the overall system, but they do not include tannins. This absence means the publicly available data does not specify tannin levels for the system that serves approximately 446,170 people across 155,577 connections.
Since tannins are organic compounds commonly found in surface waters, especially in forested or wetland areas typical of Pierce County, their presence in household water is possible. However, any assumption about tannin levels in a specific home must rely on direct water testing and not on public system-wide figures.
Understanding Seasonal and Multi-Year Variability in Public Water Data
Public water system monitoring often aggregates data across seasons and years. The Tacoma Water Division’s records include health-based violation reports but contain no documented monitoring for tannins at any time. This lack of data could reflect either low priority for tannin testing or limited regulatory mandate. Seasonal changes, such as increased runoff during rainy months, commonly affect tannin concentrations in surface water sources. Without specific monitoring data, however, it’s impossible to determine how tannin content fluctuates over time within this public system.
Sample Size and Source Depth: What the Number of Samples Indicates
The public record draws on numerous samples but none specifically measuring tannins. This means household water characteristics concerning tannins may differ markedly from the general source profile. For a homeowner, this underscores the need for private testing to establish whether tannins contribute to water coloration or other aesthetic issues. Without this, reliance on public data alone cannot confirm individual conditions or severity.
Adapting Water Treatment for Large, Secondary, or Seasonal Homes
Households larger than typical single-family residences, second homes, or seasonal properties may experience different water quality dynamics due to usage patterns or stand-by periods. If tannin-related issues have caused prior equipment failure, these variables could influence tannin accumulation or breakthrough. Repeat water assessment under varied occupancy scenarios helps clarify treatment needs, ensuring equipment can handle specific household demands.
Clarifying Terminology: Detected, Median, and Range in Water Quality Reports
Within EPA records, terms like detected simply indicate the presence of a substance during sampling without implying problematic levels. Median represents the middle value in a data set, and range shows the span between the lowest and highest measured levels. For tannins in Pierce County’s public water system, these terms are not applicable due to absent monitoring data. Therefore, individual water testing remains the definitive method to establish tannin concentration and its impact.
Given the failure of current household equipment to manage tannins effectively, evaluating tannin concentration through certified laboratory testing is the recommended step. Following that, equipment like the C-Series Yellow, Tea-Colored Tannin Water Filter ships ready to configure and is specifically designed to address tannin coloration and related issues identified in water tests. This targeted solution can restore water quality for households in Pierce County where tannin presence has been confirmed by analysis.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2025-12-31. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA SDWIS record for TACOMA WATER DIVISION CITY OF (WA5386800), surface water supply, serving 446170 people: 9 health-based violations of 12 total; lead 90th percentile 0 mg/L