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Team TFS
Team TFS
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In my last blog post why we disinfect water, I gave a brief history of why disinfection of drinking water prior to consumption is necessary.   It is a positive process step to stop life-threatening disease outbreaks such as cholera and other waterborne diseases which have devastating effects and are completely preventable.

However, the disinfection process isn’t without chemical side effects.

As drinking water comes from sources such as streams, reservoirs, and dams, often there are naturally occurring organic materials (NOM) that come from plants and animals in the water.

Even after filtration, traces of NOM can still exist in the water source.  When disinfection occurs, usually by a chlorinated method, the disinfectants will react with that material and form disinfection byproducts (DBPs).

Depending on which disinfectant is used, the typical ones being free chlorine, chloramines, chlorine dioxide, and ozone, will determine which disinfection by-products are produced.

Chlorine-based disinfectants will generally lead to the formation of haloacetic acids (HAAs), where acetic acids have one or more hydrogens replaced with a halogen.

[caption id="attachment_22862" align="alignright" width="1000"]Image-2-0412B.png Chloracetic acid[/caption]

There are over 600 known disinfection byproducts and HAAs are the most abundant.  Studies show concern over potential health implications such as the increased risk of cancer, problems in the liver, kidneys, and central nervous system.  So, it is hugely important to monitor and regulate the levels of these compounds in our drinking water as well as in swimming pools, which are highly chlorinated environments.

There are 5 haloacetic acids with the most concern, known as the HAA 5, which are:

  • Monochloroacetic acid (MCAA)

  • Dichloroacetic acid (DCAA)

  • Trichloroacetic acid (TCAA)

  • Monobromateic acid (MBAA)

  • Dibromoacetic acid (DBAA)


However, there are monitoring programs on other HAAs such as the EPA fourth unregulated contaminant monitoring rule (UCMR4), which asks for monitoring of 4 further HAAs, listed below:

  • Bromochloroacetic acid (BCAA),

  • Bromodichloroacetic acid (BDCAA),

  • Dibromochloroacetic acid (DBCAA),

  • Tribromoacetic acid (TBAA)


Collectively these compounds are known as the HAA9. How many HAAs are monitored and regulated and the maximum concentration limits vary from country to country. Please click here for a summary of current regulations.

European regulations reviewed


In the EU, HAAs were monitored but not regulated and the EU drinking water directive was over 20 years old. Thus, a review was carried out in December 2020.

The review highlighted the need for HAAs, among others, to be included in the regulated compounds list.

There is also increased pressure to make water quality more consistent across the EU, thanks to the Right 2 Water campaign powered by European citizens to highlight that not everyone has access to safe water and sanitation plus the need to reduce bottled water consumption to help with the plastic crisis.

To quote the directive, “By 12 January 2026, EU Member States shall take the measures necessary to ensure that water intended for human consumption complies with the parametric values set out in Part B of Annex I for Bisphenol A, Chlorate, Chlorite, Haloacetic Acids, Microcystin-LR, PFAS Total, Sum of PFAS and Uranium.”

The HAA 5 will be regulated at 60 ug/L - another positive step in maintaining safety standards in our precious drinking water.

As investigative work is ongoing into the new sets of iodo- disinfection byproducts, we may well see further additions to regulations as more data becomes available.

Are you prepared for the regulation updates?  Contact us now to speak with an expert.

Further reading


Blog post on swimming pool disinfection byproducts  The Shark in the Swimming Pool

Dedicated webpages on haloacetic acids and methods and disinfection byproduct analysis