Total Trihalomethanes in Drinking Water
Disinfection Byproduct · MCL: 80 ppb · 9 systems exceeding limit
Overview
Total Trihalomethanes is regulated under the Safe Drinking Water Act with an MCL of 80 ppb. The EPA Safe Drinking Water program sets and enforces the maximum contaminant levels shown here.
Health Effects
Exposure to Total Trihalomethanes above the MCL of 80 ppb may cause adverse health effects. Consult EPA fact sheets for detailed information.
Sources of Contamination
Total Trihalomethanes can enter drinking water from natural deposits, industrial discharges, or other sources.
Treatment & Removal
Treatment methods for Total Trihalomethanes include activated carbon filtration, reverse osmosis, and specialized media.
How to Remove Total Trihalomethanes From Water
These filtration methods are effective for reducing Total Trihalomethanes in drinking water:
| Filter Method | Effectiveness | Cost Range | Certification |
|---|---|---|---|
| Activated Carbon (granular or block) | 90-99% removal | $30-100 (pitcher/faucet/under-sink) | NSF/ANSI 53 |
| Reverse Osmosis (RO) | 80-90% removal | $200-500 (under-sink) | NSF/ANSI 58 |
| Aeration | 70-90% removal | $500-1500 (whole-house) | Varies |
Activated Carbon (granular or block), details
Carbon is the most effective and affordable method for THMs. Even basic pitcher filters work well.
Reverse Osmosis (RO), details
Effective but carbon pre-filter does most of the THM work.
Aeration, details
THMs are volatile and can be removed by aeration. Also reduces exposure during showers.
Water Systems with Total Trihalomethanes Detected
Cocoa, City Of
Cocoa, Florida
Tucson City Of
Tucson, Arizona
Aurora City Of
Aurora, Colorado
Minneapolis
Minneapolis, Minnesota
Ecwa Direct
Buffalo, New York
Mobile, Bd. Of W&s Comm. Of the City Of
Mobile, Alabama
Buffalo Water Authority
Buffalo, New York
Wildwood City Water Department
Rio Grande, New Jersey
Alderwood Water District
Lynnwood, Washington
Gru - Murphree Wtp
Gainesville, Florida
Springfield Water and Sewer Commission
Springfield, Massachusetts
Tuscaloosa Water & Sewer
Tuscaloosa, Alabama
Lansing Board of Water & Light
Lansing, Michigan
Kansas City Board of Public Utilities
Kansas City, Kansas
Olathe, City Of
Olathe, Kansas
Rio Rancho Water & Ww Services
Rio Rancho, New Mexico
Harford County D.p.w.
Abingdon, Maryland
Wvawc - Huntington Dist
Charleston, West Virginia
Lawton
Lawton, Oklahoma
Bloomington
Bloomington, Minnesota
Brooklyn Park
Brooklyn Park, Minnesota
Sioux City Water Supply
Sioux City, Iowa
City of Gulfport
Gulfport, Mississippi
City of Southaven
Southaven, Mississippi
City of Olive Branch
Olive Branch, Mississippi
City of Hattiesburg
Hattiesburg, Mississippi
Shreveport Water System
Shreveport, Louisiana
Newark Water Department
Newark, New Jersey
Chandler City Of
Chandler, Arizona
City of Jackson
Jackson, Mississippi
Gilbert, Town Of
Gilbert, Arizona
Atlanta
Atlanta, Georgia
Clermont Public Water System
Batavia, Ohio
Papillion, City Of
Papillion, Nebraska
Kearney, City Of
Kearney, Nebraska
Frequently Asked Questions
Total Trihalomethanes has been detected in 9 water systems that exceed the EPA maximum contaminant level (MCL) of 80 ppb, affecting approximately 2,463,205 people. Check your local water system's annual Consumer Confidence Report or search by ZIP code on this site.
Exposure to Total Trihalomethanes above the MCL of 80 ppb may cause adverse health effects. Consult EPA fact sheets for detailed information.
Effective filtration methods for Total Trihalomethanes include Activated Carbon (granular or block), Reverse Osmosis (RO), Aeration. Look for filters certified to NSF/ANSI standards for Total Trihalomethanes removal. See the detailed comparison table above for effectiveness ratings and cost ranges.
The EPA Maximum Contaminant Level (MCL) for Total Trihalomethanes is 80 ppb. The MCL Goal (MCLG), the level with no known health risk, is 0 ppb. Water systems must test regularly and notify customers if levels exceed the MCL.