New Chemical Identified in Chloraminated Drinking Water: Implications for Water Treatment Facilities and Chloramine Manufacturers

After more than forty years of research, scientists finally determined the molecular formula of a chemical found in chloraminated drinking water. 1 Using advanced analytical techniques, researchers detected and characterized the chemical, which, until recently, could not be done using standard methods due to the chemical’s low concentrations in drinking water. The new chemical, which they named chloronitramide anion, is not necessarily toxic.

The researchers suggest that chloronitramide anion has a similar composition to other chemicals of concern, which may warrant further study. However, researchers are unwilling to declare the new chemical toxic without additional research. Chloramine manufacturers, distributors, and users should closely follow the forthcoming research on toxicity, as plaintiffs’ lawyers and environmental groups will move quickly toward litigation alleging personal injuries and pushing for new regulatory limits.



Background Over 100 million people in the United States consume drinking water treated with chloramines. Chloramines are a class of chlorine-based disinfectants that kill harmful bacteria in drinking water. When added to water, chloramine naturally reacts with other materials present in the water to produce disinfectant byproducts (DBPs).

Chloronitramide anion is a chloramine DBP. Regulatory Implications Under the Safe Drinking Water Act (SDWA), EPA has the authority to establish national primary drinking water regulations (NPDWRs) for chemical disinfectants. 42 U.

S.C. § 300g-1(b)(4).

EPA must review NPDWRs every six years to determine whether revisions are warranted. Id. at (b)(9).

Since December 2016, EPA has been debating whether the existing body of scientific evidence on microbial and disinfectant byproducts warrants revising disinfectants’ NPDWRs, which includes chloramine. 2 EPA enforces chloramine’s NPDWR by setting a Maximum Residual Disinfectant Level (MRDL). The study’s authors detected the chloronitramide anion at concentrations ranging from 1 to 120 μg/L.

For reference, chloramine’s MRDL is currently limited to 4.0 μg/L and typically, limits for regulated DBPs range from 60 to 80 μg/L. 89 Fed.

Reg. 59623, 59625 (July 23, 2024). Should EPA choose to set a NPDWR for chloronitramide anion, the threat of an EPA enforcement action will force regulated entities to curtail chloramine usage while confronting the need for a new means of disinfecting drinking water.

Further, armed with the SDWA’s citizen suit provision, environmental groups can pressure EPA to target regulated entities that struggle to comply with EPA’s mandatory timeframe. See 33 U.S.

C. § 1365. The SDWA, however, is not the only source of potential liability implicated by this new chemical.

The Toxic Substances Control Act (TSCA) obligates EPA to regulate chemical substances deemed an unreasonable risk to health or the environment. 15 U.S.

C. § 2605(a). TSCA provides three avenues to obtain a rule regulating a chemical, which includes a “citizen petition.

” Id. § 2620(a). As detailed in a prior news alert , at least one environmental group convinced a federal district court that the remedy for a successful citizen petition is ordering EPA to initiate rulemaking that imposes limits on the said chemical.

See generally Food & Water Watch, Inc. v. EPA , No.

17-cv-02162, 2024 WL 4291497 (N.D. Cal.

Sept. 24, 2024). Unless a higher court holds otherwise, an environmental group copying the Water Watch strategy could obtain a judicial order forcing EPA to initiate rulemaking under TSCA even if EPA declines to regulate chloronitramide anion.

Looking Ahead EPA has yet to commit to initiating rulemaking under the SDWA for chloronitramide anion. But an EPA spokeswoman advised that “[f]urther investigation . .

. will be needed before EPA can determine if regulatory action is warranted,” which means that EPA recognizes the possibility that chloronitramide anion may eventually require its own NPDWR. 3 Scientific uncertainty works in favor of environmental groups, incentivizing them to push state and federal agencies for toxicity study funding and eventual regulation.

So, chloramine manufacturers and distributors, public and private drinking water systems, and state government agencies should closely monitor scientific developments on chloronitramide anion’s potential toxicity or agencies’ notices of intent to initiate rulemakings concerning chloronitramide anion or chloramines generally. If evidence of toxicity emerges, given environmental groups’ recent success in Food Watch , it is likely that Plaintiffs’ lawyers and environmental groups will bring similarly structured TSCA test cases using TSCA’s citizen petition provision. Given the lower standard of proof required in court relative to EPA, 4 these challengers will not necessarily wait for additional chloronitramide anion toxicity studies before taking action.

Regulated entities should take stock of their chloramine usage to prepare for either possibility. Private toxic tort lawsuits may allege contamination of drinking water from chloramine treatment—analogizing chloronitramide anion to other chemicals of concern. Any tort lawsuits alleging injuries from chloronitramide anion should be aggressively defended, and—given the absence of toxicity research—the question of whether plaintiffs can establish general causation should be frontloaded in the case schedule to try to secure an early favorable disposition.

1 Fairey, et al., Chloronitramide Anion Is a Decomposition Product of Inorganic Chloramines , Sci., Nov.

21, 2024, at 882–87. 2 Potential Revisions of Microbial & Disinfection Byproducts Rules , U.S.

Env’t Prot. Agency, https://www.epa.

gov/dwsixyearreview/potential-revisions-microbial-and-disinfection-byproducts-rules (Mar. 13, 2024). 3 Carolyn Y.

Johnson & Joel Achenbach, Mysterious Chemical Byproduct in U.S. Tap Water Finally Identified , Wash.

Post (Nov. 21, 2024), https://www.washingtonpost.

com/science/2024/11/21/tap-water-byproduct-chloronitramide-anion/ . 4 Compare 15 U.S.

C. § 2625(h), with 15 U.S.

C. § 2620(b)(4)(B). Decisions to establish or revise a NPDWR must be based on the best available scientific evidence.

42 U.S.C.

§ 300g-1 (b)(3)(A)..