Pentair Yellow, Tea-Colored Tannin Water Filter

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What the Official Record for Des Moines Water Reveals About Tannins

The EPA’s Public Water System record for Des Moines Water Works, serving Polk County, shows no direct monitoring data for tannins. This system relies on surface water sources, which are the type of water supply where natural organic compounds like tannins are more likely to occur. Although tannins themselves are not routinely tested by the system, the absence of federal data means there is no documented evidence of tannins at the system level. Homeowners experiencing tea-colored water or related stains should note that the municipal supply’s official record does not establish the presence or concentration of tannins in their tap water.

Interpreting Samples and Their Limitations in Public Water Records

Government records reflect aggregated data from many samples, but none report tannins here. The record’s sampling focuses on safety and secondary water quality factors rather than every possible constituent. A small number of samples or the lack of testing for a constituent means the data cannot confirm whether tannins are present or absent in any individual household’s water. For residents wondering about tannins in their home’s supply, this means the regional record alone is not sufficient to identify or rule out the problem.

How the Source Water Type Influences Tannin Potential in Des Moines

Des Moines Water Works uses surface water, which can contain naturally occurring tannins derived from decayed vegetation and organic materials in lakes or rivers. Groundwater wells typically show fewer tannins because these compounds tend to degrade underground. The likelihood of tannins causing tea-colored water increases with surface water use, especially if treatment processes do not specifically address organics that impart color or staining. The treatment process codes in the record show a variety of steps but do not confirm tannin removal specifically, leaving a potential gap for tannins to reach end users.

Identifying Which Household Fixtures and Appliances Show Tannin Effects First

When tannins are present, discoloration often becomes noticeable in water fixtures with frequent water contact, such as sinks, showers, and toilets. Tea-colored water stains porcelain and glass surfaces and can leave a colored film or residue. Appliances like humidifiers and coffee makers may also show signs sooner due to their water use patterns. Because tannins do not pose a health risk, residents typically first detect them through these aesthetic effects rather than taste or odor.

Seasonal and Long-Term Patterns of Water Color Problems in Surface Water Systems

Surface water source quality, including tannin levels, can vary seasonally with rainfall, temperature, and organic matter runoff. The Des Moines Water Works’ record does not include tannin monitoring over time, but generally, tannin concentration may rise during warmer months or after heavy rains when organic runoff increases. Long-term trends depend on watershed conditions and treatment adjustments, so residents noting fluctuating water color should consider timing and weather patterns as possible factors.

Testing to Confirm Tannin Presence and Next Steps in Treatment

The definitive way for a household to determine tannin presence in their water is to have a certified laboratory perform a specialized organic carbon test or a tannin-specific assay. Such analysis will measure the concentration and confirm if tannins are causing the tea coloration and stains. When tannins are confirmed, one effective approach to restore water clarity and protect plumbing is to use a Pentair Yellow, Tea-Colored Tannin Water Filter. This system ships ready to configure and is designed to reduce tannin-related discoloration at the point where water enters the home.

Where this information comes from

Source: EPA SDWIS public water system record. Sampled 2024-12-31. These figures describe the public water system's record, not the plumbing inside any individual building.

On record: EPA SDWIS record for DES MOINES WATER WORKS (IA7727031), surface water supply, serving 246055 people: 1 health-based violations of 3 total; lead 90th percentile 0 mg/L