Understanding "Detected", "Median", and "Range" in Water Sampling Records
When reviewing water quality data from government sources, terms like detected, median, and range describe the measurements found during sampling campaigns but do not directly reflect safety or treatment needs for any individual household. "Detected" means a measurement instrument found some concentration, but it is not a violation or necessarily a concern. "Median" shows the middle value among samples collected, and "range" covers the lowest and highest values observed. It is important to recognize these figures relate to broad system-wide water sampling, not to individual wells or household taps.
How Tannins Enter the Water Supply in Green Bay and Brown County
Green Bay's water source, according to the EPA's records, is surface water. Tannins commonly originate from decomposed vegetation—especially leaves and organic material—in surface water environments like lakes, rivers, and reservoirs that feed municipal supplies. These naturally occurring organic compounds color water tea-like brown but are not regulated by federal health-based standards. Although tannins themselves are not sampled by the EPA in the Green Bay system, the surface water source type is generally where tannin presence arises if any. Homeowners must test their own water specifically for tannins if concerned.
Consequences of Untreated Tannins in Household Water Over Time
If water contains tannins over a long period, homes may notice tea-colored staining on fixtures, laundry discoloration, or taste and odor changes. Tannins can also contribute to water hardness effects and make conventional disinfection less efficient. While these outcomes are aesthetic and practical rather than health hazards, persistent tannins can affect household water experience and appliance longevity. Without appropriate treatment, these signs may accumulate but do not indicate immediate safety issues.
Distinguishing Tannins From Two Commonly Confused Water Issues
Tannins are often mistaken for iron or manganese contamination because all can discolor water brown or reddish. Unlike iron or manganese, tannins do not precipitate as metals and are organic in nature. Iron and manganese issues may cause metallic taste or staining due to oxidation, while tannins tend to cause consistent tea-like coloration without metallic taste. Proper water analysis helps clarify the difference, avoiding ineffective treatment approaches designed for metals rather than organic compounds.
Interpreting Water System Measurements and Federal Standards Regarding Tannins
The EPA record for Green Bay Waterworks shows zero health-based violations and very low lead levels in 2023 sampling, which reflects safety standards but does not include tannin monitoring. Since tannins are not regulated under federal health rules, their detection or concentration in surface water is not subject to legal limits or deemed unsafe. The absence of tannin measurement data means that any tannin presence remains unquantified at the municipal level, so individual households must conduct their own testing to determine if treatment is appropriate.
For residential households facing tannin-related concerns, the Pentek Yellow, Tea-Colored Tannin Water Filter is a documented option that ships ready to configure. It is designed specifically to reduce organic color compounds like tannins and improve water clarity and aesthetic quality.
In summary, the Green Bay Waterworks municipal system serves over 100,000 residents with surface water and maintains a compliance record free of EPA health-based violations. While tannins are typical in surface water sources generally, no federal monitoring data exists for tannins in this system, underscoring the importance of individual water testing for household treatment decisions. For more detailed government data, refer to the EPA public water system records.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2023-09-30. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA SDWIS record for GREEN BAY WATERWORKS (WI4050356), surface water supply, serving 107369 people: 0 health-based violations of 4 total; lead 90th percentile 0.0025 mg/L
- ✓ 90-Day Money-BackNo restocking fees — return within 90 days.
- ✓ Manufacturer WarrantyGenuine Fleck · Pentair · VIQUA equipment.
- ✓ Free Expert SizingTalk to a specialist and buy the right system the first time.