Total Trihalomethanes in Drinking Water: Health Risks, Sources, and How to Remove It
Total Trihalomethanes are a group of organic chemicals that can be found in drinking water. They fall under the category of organic contaminants. The Environmental Protection Agency (EPA) has set the Maximum Contaminant Level (MCL) for Total Trihalomethanes at 80 μg/L.
Health Effects
Long-term exposure to Total Trihalomethanes above the standard can lead to liver, kidney, or central nervous system problems. Additionally, consuming water with elevated levels of these contaminants is associated with an increased risk of cancer. It is important to monitor and limit exposure to avoid these chronic health conditions.
How Total Trihalomethanes Gets Into Tap Water
These organic chemicals are formed as disinfection byproducts in drinking water systems. They typically occur when chlorine reacts with naturally occurring organic matter present in the water source. Consequently, tap water that has undergone chlorination treatment is the primary place where these substances are generated.
How to Remove Total Trihalomethanes From Your Water
Several treatment methods are available to reduce or remove Total Trihalomethanes from drinking water. These include the use of granular activated carbon filtration, aeration techniques, and enhanced coagulation processes. Implementing these systems helps lower the concentration of these disinfection byproducts in public and private water supplies.
Should You Test Your Water?
To check the levels of Total Trihalomethanes in your tap water, you can review your local water utility's annual Consumer Confidence Report or search for test results on WaterQ. If you use a private well, periodic laboratory testing is recommended to ensure your water meets safe guidelines. You can also look up your local water system on WaterQ or check the Total Trihalomethanes data page for reported levels in your area.
Frequently Asked Questions
Is Total Trihalomethanes dangerous in drinking water?
Consuming water containing Total Trihalomethanes over a long period can be hazardous to your health. It is linked to liver, kidney, or central nervous system problems, as well as an increased risk of cancer. Because of these chronic health concerns, it is regulated to ensure water safety.
How does Total Trihalomethanes get into tap water?
They enter tap water as disinfection byproducts. This happens when chlorine, used to treat the water, reacts with organic matter.
How can I remove Total Trihalomethanes from my water?
You can remove them using treatment systems such as granular activated carbon or aeration. Enhanced coagulation is also used in water treatment to reduce their presence.
Source: EPA National Primary Drinking Water Regulations and WaterQ National Database. For more contaminants, visit our contaminant library.
What actually removes trihalomethanes and disinfection byproducts
These are the trade-off contaminants: they exist because the water is being disinfected, and disinfection prevents far more harm than the byproducts cause. That said, they are easy to reduce. Activated carbon with an NSF/ANSI 53 VOC claim handles them well, so a modest under-sink or pitcher filter is sufficient. Levels are usually highest in summer and at the far end of the distribution network.
Works
- 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.
- Basic activated carbon (NSF 42)Fixes taste and smell. Does not remove any health-regulated contaminant.
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 | |
|---|---|---|---|---|
| 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 |
| 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 |
| APEC ROES-50 EssenceUnder-sink | Built with WQA-certified components to NSF/ANSI 58.Catch:Needs an under-sink drain connection and a spare hole for the dedicated faucet. Strips minerals — some people dislike the flat taste. | $180–240 | $50–80 | 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 trihalomethanes and disinfection byproducts.