Municipal Affairs and Environment

Haloacetic acids (HAAs)

Haloacetic acids (HAAs) are a type of chlorination disinfection by-product (CDBP) that are formed when the chlorine used to disinfect drinking water reacts with naturally occurring organic matter (NOM) in water. Haloacetic acids are a relatively new disinfection by-product.

HAAs are a collection of several different compounds. The sum of Bromodichloroacetic Acid (BrCl2AA), Dibromochloroacetic Acid (Br2ClAA), and Tribromoacetic Acid (Br3AA) concentrations is known as HAA3. The sum of Monochloroacetic Acid (ClAA), Monobromoacetic Acid (BrAA), Dichloroacetic Acid (Cl2AA), Trichloroacetic Acid (Cl3AA), and Dibromoacetic Acid (Br2AA) concentrations are known as HAA5. HAA6 refers to the sum of HAA5 and Bromochloroacetic Acid (BrClAA) concentrations. HAA6 and HAA3 together make up HAA9 (Roberts et al., 2002)1.

The reported HAAs value refer to the sum of the concentration of six haloacetic acid compounds which include mono-, di-, and trichloroacetic acids, and mono- and dibromoacetic acids, and bromochloroacetic acid.

The Guidelines for Canadian Drinking Water Quality (GCDWQ) recommend a maximum acceptable concentration (MAC) of 80 micrograms per litre (μg/L) for HAAs in drinking water, based on a locational running annual average of a minimum of quarterly samples taken in the distribution system. As per guideline, total HAAs refers to the HAA5 (the total of monochloroacetic acid (MCA), dichloroacetic acid (DCA), trichloroacetic acid (TCA), monobromoacetic acid (MBA) and dibromoacetic acid (DBA)). Sampling for HAAs in Newfoundland and Labrador began in 1999 with the main objective of collecting baseline information. Since the adoption of the new GCDWQ MAC in April 2008, HAA monitoring is being conducted in a systematic manner for all public water supplies that have chlorination.

Water facilities that derive their water from surface water (lakes, rivers, reservoirs) are likely to produce water with higher levels of disinfection by-products than facilities that draw water from groundwater. The natural characteristics of a surface water source and the characteristics of the associated watershed greatly influence water quality, including the potential formation of HAAs.

The natural factors that are key parameters to influence water quality are hydrology, topography, geology, soil, vegetation and climate. The formation of HAAs has been reported to be a function of precursor concentration (NOM), chlorine dose, chlorination pH, temperature, contact time, and bromide ion concentration.

Groundwater benefits from natural filtration. As a result, the waters pumped from wells or obtained from artesian wells and springs are often low in concentrations of NOM.

Preventative and Mitigative Measures

While control and minimization of HAAs and some CDBPs is necessary, the primary goal of disinfection of drinking water cannot be compromised. The preferred approach to control HAAs levels is to reduce the precursors in the raw water that react with the disinfectant to produce the by-products. Fine-tuning of the treatment system may also achieve a reduction in by-products without impairing disinfection. Various control measures are available to control the level of HAAs in public drinking water supplies. Control measures are site specific since the parameters that affect HAAs formation will vary for each water supply.

Chlorine is the most commonly used disinfectant in the province. Chlorine demand management could be used as one of the first mitigative options to control HAAs. A chlorine demand strategy would normally consist of management of the chlorine dose at the water supply source or the use of satellite treatment, such as re-chlorination at storage tanks or multiple chlorine injection points along the distribution system. These strategies can be used alone or in conjunction with one another.

The data below is for all sampling carried out up to December 31, 2018

The Drinking Water Quality data shown on this page is now also available via the Newfoundland and Labrador Water Resources Portal. Using the Community Water Resources Reports feature a Community can be selected to generate reports that show all of the Drinking Water Quality data the Department has collected for that community.

To see when your community has been sampled please refer to the Sampling Schedule web page.

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For additional information on HAAs or any other water resources related topics please contact us.

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