Chromium-6 in California Drinking Water: What Inland Empire Residents Need to Know

Chromium-6 — the hexavalent chromium made nationally famous by the Erin Brockovich case — is not confined to the Hinkley, California industrial contamination that put it on the map. It has been detected in water supplies serving millions of Californians, including communities throughout the Inland Empire. In Banning, California in particular, chromium-6 has been found at concentrations above California's stringent public health goal of 0.02 ppb, alongside already-extreme 249 PPM water hardness. Understanding what chromium-6 banning California data means for your family requires separating the facts from the fear — and this guide does exactly that.

What Is Chromium-6?

Chromium is a naturally occurring metal found in rocks, soil, plants, and animals. It exists in multiple chemical forms, of which two are commonly encountered in water: chromium-3 (trivalent chromium), which is an essential nutrient at low levels, and chromium-6 (hexavalent chromium), which is the form linked to health concerns.

Chromium-6 forms when chromium interacts with oxygen-rich environments, both through natural geological processes and through industrial activity. In the Inland Empire, including Banning and the wider San Gorgonio Pass region, chromium-6 in groundwater is primarily geogenic — meaning it leaches naturally from chromite-containing rock formations that are prevalent in Southern California's geology. This is different from industrial contamination like the Pacific Gas & Electric case in Hinkley, but the chromium-6 molecule itself is identical regardless of origin.

The Science Behind Chromium-6 Health Concerns

The health concerns around chromium-6 in drinking water center on its classification as a known human carcinogen when inhaled (as in industrial settings) and research data showing it causes cancer in laboratory animals when ingested at elevated levels.

The National Toxicology Program conducted studies showing that rats and mice drinking chromium-6 in water developed intestinal tumors. California's public health scientists used this data to establish a PHG of 0.02 ppb — the level at which lifetime exposure results in a less than one-in-one-million increased cancer risk. The EPA's legal limit for total chromium is 100 ppb, set in 1991 before modern understanding of chromium-6's specific toxicity was fully developed.

California set its 0.02 ppb chromium-6 PHG in 2011. In 2014, the state set an MCL for chromium-6 of 10 ppb, but this was struck down by a court ruling in 2017 on cost-benefit analysis grounds. As of 2026, California is working on a new regulation, but residents in areas with detected chromium-6 above the PHG cannot rely on legal standards alone for health protection.

Where Chromium-6 Has Been Detected in the Inland Empire

Several Inland Empire water districts have reported chromium-6 detections in their Consumer Confidence Reports and in EWG's analysis of EPA testing data. Banning's water — already notable for its 249 PPM extreme hardness — has shown chromium-6 levels above California's 0.02 ppb PHG. Hemet and parts of San Jacinto have also reported chromium-6 detections, where it is found alongside arsenic above California's health goals.

Industrial areas near Riverside and San Bernardino carry additional chromium-6 concerns from historical manufacturing activity, particularly in older industrial corridors where chromium was used in electroplating and metal finishing operations. In these areas, chromium-6 may have both natural and industrial origins.

It's important to note that most Inland Empire water utilities meet federal and state legal standards. "Above the PHG" does not mean "illegal" — it means the detected level exceeds the stricter, health-protective benchmark that California scientists recommend for negligible lifetime health risk.

Chromium-6 and Banning, CA: The Specific Situation

For Banning residents, chromium-6 is one part of a two-challenge water quality picture. The city's 249 PPM hardness — the highest in the San Gorgonio Pass — creates significant daily home damage and quality-of-life impacts. The chromium-6 detection above California's PHG adds a health dimension to the equation.

Banning draws from 19 active groundwater wells. The chromite-rich geology of the San Gorgonio Pass means that local well water is particularly susceptible to geogenic chromium-6. Unlike contamination from a localized industrial source that can be remediated, geogenic chromium-6 is a permanent feature of the regional geology. For Banning residents, long-term treatment at the tap is the practical answer.

How to Remove Chromium-6 from Drinking Water

Standard water softeners address hardness but do not remove chromium-6. The technologies proven effective for chromium-6 removal include reverse osmosis (RO) filtration, which achieves 90–99% removal through a semipermeable membrane that blocks heavy metal ions at the molecular level. Strong base anion exchange systems can also remove chromium-6 effectively, and coagulation/filtration processes are used at the municipal scale.

For residential use, under-sink reverse osmosis is the most practical and cost-effective solution. An RO system installs beneath the kitchen sink and provides a dedicated tap for drinking and cooking water that has been filtered to remove chromium-6, arsenic, lead, nitrates, PFAS, and hundreds of other contaminants. The membrane does require periodic replacement (typically every 2–3 years depending on water quality and usage), but operating costs are minimal.

For comprehensive protection in Banning and other high-hardness IE cities, the most effective approach combines a whole-home water softener (addressing the extreme hardness that damages every pipe and appliance in your home) with an under-sink RO system (producing chromium-6-free water at your kitchen tap). Select Source Water's HYGIA+ system supports this two-stage configuration.

Should You Be Worried?

The evidence on chromium-6 at low concentrations is evolving, and scientists continue to debate the precise dose-response relationship. What is clear is that California's public health community, after reviewing the best available science, set a PHG of 0.02 ppb — and that detections above this level are worth addressing if you can do so effectively and affordably.

Many Inland Empire families choose to use reverse osmosis drinking water filtration not because their water is dangerously contaminated, but because the science is uncertain enough that reducing exposure through affordable, available technology is a sensible precautionary choice. An under-sink RO system that provides chromium-6-free drinking water typically costs $500–$1,500 installed, depending on the system configuration.

Learn more about our service in Banning, Hemet, Riverside, and throughout the Inland Empire. Call Select Source Water at (833) 422-7765 to schedule a free in-home water test. We'll test your water, show you the results in real time, and explain exactly what's in your water and what your options are — with no pressure and no obligation.