For more than a century, public water systems have used disinfectants like chlorine and chloramines to kill bacteria, viruses, and parasites. Without disinfection, even clear-looking water can carry pathogens responsible for cholera, typhoid, and dysentery. Modern treatment has saved countless lives, and that's not up for debate.

But here's the part most homeowners never hear:

According to recent research from Stevens Institute of Technology, disinfecting chemicals can, in theory, create byproducts we don't yet fully understand — some of which may affect human health.

That doesn't mean "tap water is unsafe." It means disinfecting water is a tradeoff: it protects you from microbes, but it can also create a chemical shadow that's harder to see and harder to regulate.

The EPA explains it plainly:

"Disinfection byproducts are formed when disinfectants used in water treatment plants react with bromide and/or natural organic matter (i.e., decaying vegetation) present in the source water."
— U.S. Environmental Protection Agency

In other words, the disinfectant isn't the only thing in the water. When source water contains natural organic carbon — from leaf litter, soil, runoff — chemistry happens, and new compounds can form.

Don't misunderstand — disinfection is critical. Since the early 1900s, it has dramatically lowered rates of infectious disease spread through untreated water. And the most important question — does the benefit of chlorination outweigh the health risks of DBPs? — has a clear answer from water utilities: Yes.

The concern isn't that treated water is dangerous. The concern is that there may be more to the picture than what's currently regulated.

Here's the simplest way to think about it:

Organic matter in source water + disinfectant + time = DBPs

• Heat can accelerate reactions — so levels can rise seasonally in summer.
• Different disinfectants (chlorine vs. chloramine) produce different mixtures of byproducts.
• Chlorine reacts with naturally occurring total organic carbon (TOC) left over after organic materials break down in rivers, lakes, and streams.

Many byproducts exist, but only a small group is regulated. Here are the main categories and EPA maximum contaminant levels:

EPA Maximum Contaminant Levels for Regulated DBPs

EPA materials state that some DBPs — such as THMs and HAAs — have been linked to potential health risks, including increased risk of cancer and reproductive or developmental issues at elevated exposure levels.

Why This Research Matters

Researchers at Stevens Institute have identified several hundred additional DBPs that we "don't know much about" — and some may be more toxic than the ones currently regulated.

• Built a model using toxicity data for 227 known chemicals
• Predicted toxicity for 1,163 disinfection byproducts
• Found some unregulated candidates had potential toxicity 2 to 10 times higher than some EPA-regulated chemicals

This isn't just academic paranoia. EPA's own working group notes that more than 700 DBPs have been identified, while current rules mainly regulate THM4 and HAA5 as proxies for the wider mixture.

Bottom line: The regulatory framework covers a small, well-studied slice of a much larger chemical picture. That's not a reason to panic — it's a reason to filter.

You don't need to panic. You need a plan. Here are three practical tools, ranked by what they do best.

Disinfectants protect you from microbes — full stop. That benefit is real and proven over a century of public health history. But disinfectants can also create DBPs, and emerging research suggests there may be unregulated byproducts we haven't fully characterized yet.

If you want practical, layered protection: