Fleck Chromium-6 Filter

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Have you noticed any subtle differences in your tap water's appearance or taste in La Crosse? One factor contributing can be the presence of chromium-6, also known as hexavalent chromium or Cr(VI). While La Crosse Waterworks sources its water from groundwater, federal monitoring between 2014 and 2015 found chromium-6 detected in 31 of 33 samples, with a median concentration of 0.86 micrograms per liter (µg/L or ppb) and a highest recorded value of 1.6 µg/L. Importantly, these measurements are specific to the municipal water system and do not represent individual household water quality. If your treatment equipment is struggling to keep pace, understanding chromium(VI) behavior helps guide the next steps.

How do ion exchange and reverse osmosis differ in handling chromium-6 specifically?

Ion exchange and reverse osmosis (RO) are common technologies used to address chromium(VI) presence, but they operate differently on the chemical.

• Ion exchange selectively swaps chromium-6 ions from water onto resin beads, reducing hexavalent chromium levels effectively when maintained properly.
• Reverse osmosis uses a semipermeable membrane to filter out a broad range of dissolved substances, including chromium in its hexavalent form, by physically blocking them from passing through.

Each method has its strengths depending on household water profiles and demand volumes.

How can chromium’s oxidation state change between the groundwater source, distribution mains, and your tap?

Chromium exists in multiple oxidation states; hexavalent chromium (Cr(VI)) is one, and reduction can convert it to trivalent chromium (Cr(III)), which behaves differently in water. Factors influencing these changes include:

• Water chemistry and pH variations along the distribution system.
• Presence of natural organic matter or disinfectants that can alter oxidation states.
• Contact with plumbing materials that may promote chemical reactions.

As a result, the form and concentration of chromium at your tap may differ from samples taken at the groundwater source or distribution points.

How do you measure your household’s water demand relative to treatment capacity?

Your existing equipment’s challenge in keeping up with chromium(VI) could stem from a mismatch between its capacity and your household’s daily water use. Estimating your daily water demand (gallons per day) is key. Once measured, this demand figure can be compared against documented treatment capabilities of available equipment. Higher usage or simultaneous demand from multiple fixtures can reduce effective treatment time per volume of water, leading to less chromium-6 contact time and breakthrough.

What does the seasonal or multi-year variation in chromium-6 levels reveal?

The available EPA Unregulated Contaminant Monitoring Rule 3 (UCMR3) data for La Crosse Waterworks covers a one-year span from June 2014 to June 2015. Within this period, chromium-6 was persistently detected in most samples, with concentrations varying from just above 0.03 µg/L to 1.6 µg/L. This suggests some fluctuation but overall consistent presence over that year. Longer-term or seasonal monitoring data would be required to identify broader trends or shifts in chromium(VI) levels.

How many samples and wells support the chromium-6 data for La Crosse, and what does the sample size imply?

The chromium-6 data is based on 33 samples taken from the La Crosse Waterworks system, which serves approximately 53,000 people via 16,176 connections. The samples represent a federal occurrence survey rather than compliance testing. While 33 samples provide an overview, they are limited in scope for detailed variation patterns across all sources or times. They do establish that chromium-6 presence in the system is common and measurable but not uniform at every moment or location.

If your home's treatment equipment is struggling to maintain chromium-6 levels within your expectations given your household's water demand, consider equipment designed to handle chromium(VI) effectively and at your measured usage. One such option that ships ready to configure is the Fleck Chromium-6 Filter. It addresses hexavalent chromium in residential settings, scaling treatment capacity to meet daily household flow and helping ensure consistent reduction aligned with your needs.

Where this information comes from

Source: EPA SDWIS public water system record. Sampled 2015-06-16. These figures describe the public water system's record, not the plumbing inside any individual building.

On record: EPA UCMR3 monitoring (2013-2015) for La Crosse Waterworks (WI6320309), WI: 66 results across 2 listed contaminants, 60 detections above the reporting level; no federal MCL for hexavalent chromium; total chromium MCL 100 ug/L