Search by issues or solutions
ico Haloacetic acids in water

Haloacetic acids in water

What are haloacetic acids?

Haloacetic acids (HAA) are a group of compounds that are formed when the chlorine used to disinfect drinking water reacts with naturally occurring organic matter. They are a by-product of water chlorination.

Total haloacetic acids refers to the sum of monochloroacetic acid (MCA), dichloroacetic acid (DCA), trichloroacetic acid (TCA), monobromoacetic acid (MBA), and dibromoacetic acid (DBA).


  • In Canada, the maximum acceptable concentration (MAC) for total haloacetic acids (HAA) in drinking water is 0.08 mg/L (80 µg/L) based on a locational running annual average of a minimum of quarterly samples taken in the distribution system.
  • Drinking water regulations in Quebec set a maximum level of 0.06 mg/L (60 μg/L) for the sum of the most common HAAs. That level is based on an annual average, as HAA concentrations in finished water can vary seasonally.
  • Provinces and territories can set limits that are below the Canadian guideline level.

Health effects

  • Since haolacetic acids include five different compounds, the health effects associated with exposure to that group of substances will vary with the specific compound.
  • The recommended maximum acceptable concentration (MAC) is primarily designed to be protective of the health effects of dicholoracetic acid (DCA), the compound that would pose the most significant health concerns.

How can you prevent the formation of HAAs in water?

To prevent the formation of HAAs in water, you can treat organic matter (total organic carbon, or TOC) such as tannin and lignin, as well as bromide, prior to chlorination.

How can Magnor help?

Magnor manufactures anion exchange resin systems that can help control TOC (total organic carbon) levels. Our custom-built systems effectively address the root cause of haloacetic acid formation as a result of chlorination.