NDMA and Other Nitrosamines: Precursor Control, Treatment Practices and Distribution System Operations to Achieve Regulatory Compliance

Jun 6, 2019

Chloramines have been replacing chlorine as a secondary disinfectant as a cost-effective means to comply with stricter trihalomethane (THMs) and haloacetic acid (HAA) regulations. Chloramines have been shown to minimize the formation of THMs and HAAs, but they favor the formation of N-nitrosodimethylamine (NDMA), the most frequently detected nitrosamine. Also, increased contributions to source waters from treated wastewater discharges have led to elevated levels of nitrosamine precursors. Moreover, the commonly used polymer polyDADMAC and certain anion exchange resins are a source of nitrosamines or their precursors. Recent research indicates that certain materials in the distribution system may be a source of nitrosamines or their precursors.

In 2012, WRF initiated this Research Area to provide information to regulatory agencies and prepare water utilities for potential regulations. A comprehensive multi-year research agenda was developed that consisted of projects covering occurrence, formation, precursor identification, and control strategies.


Research Area Objectives

  1. Investigate the contribution of source water quality, treatment processes, and distributions system operations to the total pool of nitrosamine precursors
  2. Develop control strategies to prevent or minimize the formation of nitrosamines from source to tap
  3. Identify unintended consequences and cost of compliance


Research Area Project Timeline and Value

Investigating Alternative Coagulant Aids to PolyDADMAC

  • Timeline: 2012–2015
  • Total Project Value: $540,670
  • Research Area Objectives: Precursors, Treatment, Other

Nitrosamine Occurrence Survey

  • Timeline: 2013–2016
  • Total Project Value: $611,902
  • Research Area Objectives: Occurrence, Precursors

Unintended Consequences of Implementing Nitrosamine Control Strategies

  • Timeline: 2013–2017
  • Total Project Value: $376,710
  • Research Area Objectives: Occurrence, Precursors, Treatment, Other

Relative Importance and Contribution of Anthropogenic and Natural Sources of Nitrosamine Precursors

  • Timeline: 2014–2017
  • Total Project Value: $433,564
  • Research Area Objectives: Occurrence, Treatment

Effect of GAC on the Removal of DBPs of Health Concern

  • Timeline: 2014–2018
  • Total Project Value: $697,709
  • Research Area Objectives: Occurrence, Precursors, Treatment, Other

Understanding the Source and Fate of Polymer-Derived Nitrosamine Precursors

  • Timeline: 2015–2018
  • Total Project Value: $531,456
  • Research Area Objectives: Precursors, Treatment, Other

Biological Treatment: NDMA Control of Sources of Precursors

  • Timeline: 2016–2019
  • Total Project Value: $554,583
  • Research Area Objectives: Precursors, Treatment

Cumulative Project Value for Research Area: $3,746,594


Projects Funded Outside of the Research Area Program that meet a Research Area Objective

Controlling the Formation of Nitrosamines During Water Treatment

  • Year Completed: 2015
  • Funding Program: RAC
  • RA Objectives: Treatment

Seasonal Changes in NDMA Formation Potential and its Removal During Water Treatment

  • Year Completed: 2016
  • Funding Program: TC
  • RA Objectives: Precursors, Treatment

Major Sources of Nitrosamine Precursors in Raw Waters

  • Year Completed: 2017
  • Funding Program: TC
  • RA Objectives: Precursors, Treatment



RAC = Research Area Council

TC = Tailored Collaboration

Project Status

Year Initiated: 2012

Year Completed: 2016


Advisory Committee Members

  • Susan Andrews, University of Toronto, Canada
  • Eric Dickenson, Southern Nevada Water Authority (SNWA)
  • Michael Elovitz, EPA
  • Michael Hotaling, Newport News, VA
  • Stuart Krasner, Metropolitan Water District of Southern California (MWDSC)
  • Issam Najm, Water Quality & Treatment Solutions (WQTS)
  • Paul Westerhoff, Arizona State University
  • Steve Via, AWWA
  • Zaid Chowdhury, Garver