Bromate in Drinking Water
Found in 621 water systems • disinfection_byproducts
Updated September 2026 • Data from EWG & EPA
What is Bromate and Why Does It Matter?
BROMATE: A HIDDEN RISK IN TREATED DRINKING WATER
What is bromate and how does it get into your water?
Bromate (BrO3-) is a chemical that forms when water treatment plants use ozone to disinfect drinking water. Ozone is highly effective at killing bacteria and viruses, but when it reacts with naturally occurring bromide in water, it creates bromate as a byproduct. This means bromate isn't dumped into water intentionally—it's an unwanted consequence of trying to make water safer. Bromide itself occurs naturally in groundwater and surface water, particularly in coastal regions and areas with mineral-rich geology. When treatment plants add ozone to eliminate pathogens, they're essentially trading one problem for another if they don't manage the process carefully.
The problem is widespread. Out of 621 water systems tested, 600 exceeded the EWG health guideline for bromate. The average level found was 1.64 parts per billion (ppb), but some systems reached as high as 18.0 ppb—more than 18 times the EWG recommendation. This isn't a rare issue affecting a handful of communities. It's a systemic problem affecting hundreds of water systems across the country.
Health effects: What does bromate do to your body?
Bromate is classified as a probable human carcinogen by the EPA. Animal studies show it can increase cancer risk, particularly kidney and thyroid cancers, with long-term exposure at elevated levels. The EWG health guideline is set at 0.1 ppb based on these cancer risks. In contrast, the EPA's legal drinking water standard allows up to 10 ppb—100 times higher than the EWG guideline. This gap matters. The EPA standard was set decades ago and reflects older science. The EWG guideline incorporates newer research suggesting cancer risk at lower exposures than previously thought.
Short-term exposure to bromate isn't typically dangerous, but chronic exposure—drinking contaminated water daily for years—is where the real concern lies. Children may be at higher risk because their bodies are still developing and they drink more water relative to their body weight. For families in affected areas, reducing bromate exposure over time is a practical way to lower long-term cancer risk.
Regulation: Why is bromate still in drinking water?
The EPA set its 10 ppb standard in 1992, and that limit remains the legal requirement today. Water systems must stay below this level or face enforcement action. However, the EWG guideline of 0.1 ppb reflects current cancer research and is significantly stricter. Most water systems meet the EPA standard but exceed the EWG guideline—which is exactly what the data shows. This creates a frustrating situation: your water is technically "legal" but may carry more risk than independent health experts recommend.
Geographic patterns: Why are some regions hit harder?
Bromate contamination is heavily concentrated in Texas (147 affected systems), California (97), New Jersey (55), Florida (45), and Kansas (35). Texas and California dominate because they have large populations relying on treated surface water and use ozone disinfection widely. Coastal states like California, New Jersey, and Florida have naturally higher bromide levels in their water sources, making bromate formation more likely during treatment. Texas's size and reliance on ozone treatment create the perfect conditions for bromate formation.
How to remove bromate from your water
Reverse osmosis (RO) systems are highly effective, removing up to 99% of bromate. Granular activated carbon (GAC) filters remove some bromate but are less reliable than RO. Ion exchange resins don't effectively remove bromate. If you live in one of the affected states—especially Texas, California, or New Jersey—testing your water for bromate is a smart first step. Many municipal water systems publish annual water quality reports that list bromate levels. If your water contains bromate above the EWG guideline, a whole-home reverse osmosis system provides the most comprehensive protection for drinking and cooking water.
Regulatory Standards for Bromate
| Standard | Level | Notes |
|---|---|---|
| EWG Health Guideline | 0.10 ppb | Stricter, based on latest science |
| EPA Legal Limit (MCL) | 10 ppb | Legally enforceable standard |
| Average Detected Level | 1.64 ppb | Across all tested systems |
| Highest Detected Level | 18 ppb | Worst-case system |
Cities With the Highest Bromate Levels
| # | City | Detected Level | People Served |
|---|---|---|---|
| 1 | Hope, KS | 18 ppb | 312 |
| 2 | Herington, KS | 18 ppb | 2,332 |
| 3 | Woodbine, KS | 18 ppb | 160 |
| 4 | Wildomar, CA | 10 ppb | 4,026 |
| 5 | Lake Elsinore, CA | 10 ppb | 165,586 |
| 6 | St. Cloud, FL | 8.41 ppb | 542 |
| 7 | Orlando, FL | 8.41 ppb | 1,043 |
| 8 | Los Gatos, CA | 6.53 ppb | 152 |
| 9 | Houston, TX | 5.77 ppb | 5,160 |
| 10 | Houston, TX | 5.77 ppb | 5,061 |
| 11 | Justin, TX | 5.77 ppb | 4,409 |
| 12 | Houston, TX | 5.77 ppb | 3,897 |
| 13 | Houston, TX | 5.77 ppb | 3,090 |
| 14 | Houston, TX | 5.77 ppb | 2,955 |
| 15 | Argyle, TX | 5.77 ppb | 12,720 |
States Most Affected by Bromate
How to Remove Bromate From Your Water
Standard pitcher and refrigerator filters with basic activated carbon cannot effectively remove bromate because it is an inorganic oxyanion that does not bind well to unmodified carbon. Bromate requires advanced oxidation, reverse osmosis, or ion exchange with bromide-selective resins.
Standard pitcher filters and carbon-only filters do not reliably remove Bromate. A reverse osmosis system with NSF/ANSI 58 certification is the most reliable solution.
Bromate removal requires reverse osmosis (effective at 85-95%), ion exchange resins specifically designed for bromide/bromate, or GAC pre-treated with specialty media. Standard charcoal filters are inadequate.
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Shop Hydrogen FlaskFrequently Asked Questions
Is Bromate in my drinking water?
Bromate was detected in 621 water systems across the US. Check your city's water quality report to see if it affects your water supply.
What are the health effects of Bromate in water?
Bromate has been associated with various health concerns at elevated levels. The EWG has set health guidelines that are typically stricter than EPA legal limits.
Which city has the most Bromate in its water?
Based on our analysis, Hope, KS has the highest detected levels of Bromate in its water supply.
How do I remove Bromate from my water?
Reverse osmosis (RO) systems are generally the most effective at removing this contaminant. Check the filtration recommendations section for specific guidance.
Related Contaminant Guides
Data sources: Environmental Working Group (EWG) Tap Water Database, U.S. EPA Safe Drinking Water Information System (SDWIS)
Last updated: September 2026
Methodology: Contaminant levels are compared against both EPA legal limits (Maximum Contaminant Levels) and EWG health guidelines, which are often stricter and based on the latest scientific research.
