Chloramines & Disinfection Byproducts
What is Chloramines & Disinfection Byproducts?
To stop waterborne disease, utilities disinfect drinking water with chlorine or chloramine (chlorine combined with ammonia). This is essential and saves lives, but there's a tradeoff: the disinfectant reacts with natural organic matter in the water to form disinfection byproducts (DBPs), most notably total trihalomethanes (TTHMs) and haloacetic acids (HAA5).
Health effects
Long-term exposure to disinfection byproducts has been associated with increased cancer risk and reproductive and developmental concerns. Chloramine itself is also a common cause of the chlorine taste and odor many people notice in tap water.
In DC-metro tap water
Utilities across the DC metro that draw from the Potomac River share this profile, which is why TTHMs and HAA5 show up above EWG health guidelines in city after city in the region. It's the single most common contaminant class on our local water reports.
How to remove it at the tap
High-quality activated carbon reduces chlorine, chloramine, and their byproducts, improving taste immediately. A reverse osmosis system pairs that carbon filtration with an RO membrane to reduce disinfection byproducts along with dissolved metals and PFAS, a comprehensive fix at the tap.
Where Chloramines & Disinfection Byproducts shows up locally
Local water reports where this contaminant class is documented in the utility's data or watershed. Open your area to see the specifics and look up your exact zip code.
Frequently asked
What are TTHMs and HAA5?
They're disinfection byproducts, groups of chemicals formed when chlorine or chloramine reacts with organic matter in water. They're regulated by the EPA but frequently sit above the stricter EWG health guidelines.
Why does my tap water smell like chlorine?
That's typically chloramine or chlorine used for disinfection. Carbon filtration and reverse osmosis both reduce that taste and odor.
Does reverse osmosis remove disinfection byproducts?
Yes. A multi-stage RO system with carbon pre-filtration reduces chloramine and disinfection byproducts like TTHMs and HAA5 at the point of use.
Related guides
The gap between what's legal and what's healthy
A utility can pass every federal test and still deliver water far above the levels health scientists consider safe. Federal legal limits were largely set decades ago; the health-based guidelines below reflect current cancer- and development-risk research.
Federal law allows 533× the health guideline
Federal law allows 600× the health guideline
Sources: EPA National Primary Drinking Water Regulations (legal limits) and the EWG Tap Water Database / state public-health goals (health-based guidelines). A reverse osmosis system reduces every contaminant above at the point of use.