Chlorine Dioxide in Drinking Water: Health Risks, Sources, and How to Remove It
Chlorine dioxide is a chemical substance used in drinking water systems, categorized as a disinfectant. The U.S. Environmental Protection Agency (EPA) has established a Maximum Contaminant Level (MCL) of 0.8 mg/L for this substance to protect public health. Exceeding this regulatory limit can lead to potential health concerns.
Health Effects
Consuming water with elevated levels of chlorine dioxide can result in health issues, particularly anemia. In addition, infants exposed to high levels may experience adverse nervous system effects. Monitoring water quality is important to avoid these potential health impacts.
How Chlorine Dioxide Gets Into Tap Water
Chlorine dioxide enters drinking water supplies primarily through water disinfection processes. Municipal water treatment facilities use it to control microbes and ensure water safety. Consequently, trace amounts may remain in the tap water delivered to households.
How to Remove Chlorine Dioxide From Your Water
To reduce or remove chlorine dioxide from your drinking water, treatment systems using activated carbon filtration are effective. These filtration methods are commonly used to target and absorb the disinfectant from household water. Using properly maintained activated carbon filters can help ensure water quality is maintained.
Should You Test Your Water?
To check for chlorine dioxide in your water, you can review your local utility's annual consumer confidence report or search the WaterQ database. For private supply testing, consulting a certified local laboratory is recommended. You can also look up your local water system on WaterQ or check the Chlorine Dioxide data page for reported levels in your area.
Frequently Asked Questions
Is Chlorine Dioxide dangerous in drinking water?
At levels above the EPA limit, chlorine dioxide can present health concerns. It may cause anemia in consumers, and infants exposed to it can experience nervous system effects. Keeping levels below the MCL of 0.8 mg/L helps prevent these risks.
How does Chlorine Dioxide get into tap water?
Chlorine dioxide is introduced into tap water during the water disinfection process at treatment facilities. It is used to sanitize water before it is distributed to homes.
How can I remove Chlorine Dioxide from my water?
You can remove chlorine dioxide from your drinking water by using activated carbon filtration systems. These filters are designed to capture and reduce the concentration of the disinfectant in household tap water.
Source: EPA National Primary Drinking Water Regulations and WaterQ National Database. For more contaminants, visit our contaminant library.
What actually removes chlorine taste and smell
This is the one problem where the cheap answer is the right answer. Any activated carbon filter certified to NSF/ANSI 42 removes chlorine taste and odor, and a $25 pitcher performs as well as a $1,000 system for this specific job. Do not let a chlorine smell be upsold into a whole-house purchase. Letting water sit uncovered in the fridge for a few hours also works, for free.
Works
- Basic activated carbon (NSF 42)Fixes taste and smell. Does not remove any health-regulated contaminant.
- Carbon certified for lead (NSF 53)The cheapest thing that genuinely removes lead, cysts and many VOCs.
- Reverse osmosis (NSF 58)The broadest removal available at home: arsenic, nitrate, fluoride, PFAS, TDS.
Will not fix this
- Ion-exchange water softener
- UV disinfection (NSF 55)
Options that carry the right certification
Ordered cheapest-adequate first. Prices are indicative bands and move often.
| Product | Certification | Upfront | Per year | |
|---|---|---|---|---|
| Brita Elite Pitcher FilterPitcher | NSF/ANSI 42 and 53 certified, including a lead reduction claim.Catch:No fluoride, nitrate or arsenic reduction. Not PFAS-rated. | $25–40 | $50–70 | Check price |
| PUR PLUS Faucet MountFaucet mount | NSF/ANSI 42, 53 and 401 certified, including lead.Catch:Slows flow noticeably and will not fit every faucet. No fluoride or nitrate claim. | $25–45 | $60–90 | Check price |
| Aquasana AQ-5200 Under-SinkUnder-sink | NSF/ANSI 42, 53, 401 and P473 certified.Catch:Carbon, not RO — no meaningful fluoride, nitrate or arsenic reduction. | $110–160 | $80–120 | Check price |
Certification listings change. Before buying, confirm the current listing for the exact model in the NSF certified products database — a manufacturer's marketing page is not a certification. WaterQ earns a commission on purchases made through these links at no extra cost to you; see our affiliate disclosure. This is general information, not medical or engineering advice.
For a full breakdown of certifications, running costs and the models worth considering, see our buying guide for chlorine taste and smell.