Researchers tested spring, groundwater, and purified bottled waters against local tap to see how treatment shapes the byproducts that emerge — and the differences were striking.
By
How to Make Lemony White Bean DipClose
:max_bytes(150000):strip_icc():format(webp)/Fewer-Disinfection-Byproducts-BottledWater-FT-DGTL0226-bb7e2b2a08ab4dde974c35caf14eb2c9.jpg)
- A new study found that bottled water contains lower levels of disinfection byproducts (DBPs) than chloraminated tap water, averaging less than half the amount found in typical U.S. tap samples.
- Researchers detected DBPs—including trihalomethanes and haloacetic acids—in all 10 bottled water brands tested, though levels remained relatively low.
- Spring and groundwater brands tended to have fewer DBPs than purified bottled waters, making them the better choice for minimizing chemical byproducts.
The news hasn’t been great for bottled water fans lately. In January, Food & Wine reported on a new study showing that the more bottled water you drink, the more microplastics you consume, and another study showing that bottled water may contain more bacteria than you might expect. And don’t even get us started on what happens when you leave bottled water in a hot car for too long.
Now, a new study published in the journal Water Research is giving bottled water the silver lining it desperately needs.
In the new March issue, researchers from the University of South Carolina published findings measuring levels of disinfection byproducts (DBPs) in bottled water compared to chloraminated tap water. The study noted that bottled water often begins as municipal tap water, which is sometimes further disinfected. This process, the researchers added, can form DBPs, chemical compounds created when disinfectants react with natural organic matter.
This Is the Bottled Water Brand Americans Reach for Most, According to New Data
The researchers noted that some of these DBPs are already regulated in bottled water by the U.S. Food and Drug Administration (FDA); however, many more fly under the unregulated radar. To find out which ones may be lurking in your water, the researchers purchased 10 popular brands of bottled water from local stores, including lower-cost “grocery” brands, mid-tier “name” brands, and higher-end “designer” brands. Some of the water was labeled as “purified” (often just code for treated tap water), while others were labeled as spring or groundwater. They also collected a sample of local tap water (treated with chloramine) for comparison with the bottled brands.
The researchers then tested for 64 different DBPs, including 50 unregulated DBPs that had not previously been measured in bottled water. They found that every bottled water sample they tested contained some level of disinfection byproducts, but at relatively low levels, ranging from 0.01 to 22.4 micrograms per liter, or up to about 22 millionths of a gram in roughly 34 ounces of water. By comparison, the tap water sample they analyzed contained 47.3 micrograms per liter, and previous studies suggest U.S. tap water averages closer to 52 micrograms per liter, about double the highest bottled water level measured in this study.
| Bottled water vs. tap water: How do DBP levels compare? | |||
|---|---|---|---|
| Water Type | DBP Levels in This Study | How It’s Treated | What to Know |
| Purified bottled water | 0.01–22.4 µg/L (some samples near the higher end of the bottled range) | Often municipal tap water that has been further treated (e.g., reverse osmosis, distillation, or carbon filtration) | May still contain DBPs formed during disinfection. Levels varied by lot. |
| Spring/groundwater bottled water | Generally lower overall DBPs than purified brands | Sourced from underground aquifers; may be disinfected but often undergoes less treatment than purified water | Showed lower DBP levels in this study, but not DBP-free. |
| Chloraminated tap water (sample) | 47.3 µg/L | Treated with chloramine to kill pathogens | Higher DBPs than any bottled sample tested, but within federal regulatory limits. |
| Average U.S. tap water (prior research) | ~52 µg/L | Typically chlorinated or chloraminated | Federal EPA limit for total trihalomethanes is 80 µg/L. |
Here’s how disinfection byproduct (DBP) levels in bottled water brands stack up against chloraminated tap water samples and prior U.S. averages.
And a hot tip: If you’re hoping to score the bottled water with the lowest levels of DBPs, go for spring and groundwater, which showed lower overall DBPs than purified brands.
As for which byproducts they identified, the team reported that trihalomethanes and haloacetic acids had the highest concentrations. Both are common DBPs that form when chlorine reacts with organic matter in water. (However, some studies have linked long-term exposure at high levels to an increased risk of certain cancers.) The researchers also found several unregulated DBPs, including dibromoacetonitrile, which is carcinogenic.
The one thing the team couldn’t do was say with certainty that there is a “safest” brand of water, because DBP levels varied from lot to lot, making brand-level comparisons impossible. As for what’s next, the team hopes their work can inform future studies tracking these DBPs over time to see how they develop as water sits on the shelf.
Tap Water Disinfection May Form Far More Chemical Byproducts Than Regulators Track, Study Finds
Bottom line: Bottled water isn’t DBP-free — but it may contain lower levels than some tap water. If you’re concerned, spring water and proper storage are your best bets. And as always, balance convenience, cost, and environmental impact before stocking up.
CLICK HERE FOR MORE INFORMATION
https://www.foodandwine.com/tap-vs-bottled-water-disinfection-byproducts-usc-study-2026-11909742
GET WET! 