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What are haloacetic acids?

Do Water Filters Remove Haloacetic Acids?


Haloacetic acids (HAA5) are the unintended byproducts of chlorine disinfection of drinking water. Unfortunately, while disinfection is important for controlling bacteria and other pathogens, long term exposure to HAA5 has been linked to harmful health effects related to pregnancy and cancer.

Installing the right filtration systems can help keep your drinking water safe. 

What Are Haloacetic Acids (HAA5)?

Haloacetic acids or HAAs/HAA5 are a group of five disinfection by-products (DBPs) that are created when chlorine and/or chloramine react with naturally occurring organic matter found in certain water supplies during treatment. The resulting HAA5 compounds include:

  • Dichloroacetic acid
  • Trichloroacetic acid
  • Monochloroacetic acid
  • Bromoacetic acid
  • Dibromoacetic acid 
Haloacetic Acids in Water Infographic

    Health Symptoms of HAA5 in Drinking Water

    The EPA states that drinking water containing haloacetic acids above the regulatory limit of 60 parts per billion (PPB) over many years may lead to health issues with the liver, kidneys, or central nervous system, as well as an increased risk of cancer.[1]

    Studies have also found that HAA5 exposure can lead to harmful effects to fetal growth and development during pregnancy.[2]

    How to Tell If Your Water Has HAA5

    Unfortunately, haloacetic acids do not cause changes to water’s smell, appearance, or taste. 

    Higher levels of these compounds are more likely to be found in water supplies sourced from surface water—like rivers or reservoirs—rather than groundwater because soil and rock act as filters for removing organic matter that lead to DBPs. 

    Public water systems are also required to notify their customers if haloacetic acids exceed a maximum contaminant level (MCL) of 60 PPB.

    Contacting your local utility or public health department is a good first step toward finding out which contaminants may be in your drinking water distribution system. Additionally, water testing can tell you what concentrations of HAA5 are at your tap.

    Haloacetic Acids Water Test
    6 Analytes Tested
    $ 235.00

    At-Home Water Treatments for HAA5 

    If you have been issued a notice or are concerned that haloacetic acids may be in your drinking water, there are several options for filtering water at home. Always be sure to check that the device you choose is actually certified to remove HAA5. NSF/ANSI Standards 42 & 53 cover HAA5 removal.[3]

    Does Reverse Osmosis Remove Haloacetic Acids?

    Yes, reverse osmosis filters have been shown to reduce HAA5. While expensive, they typically remove more contaminants than other filters.

    Do Activated Carbon Filters Remove Haloacetic Acids?

    Yes, activated carbon can reduce HAA5 levels in tap water.

    Do Filter Pitchers Remove Haloacetic Acids?

    Depending on the type of technology the pitcher uses (such as those with activated carbon filters), point-of-use filters–like the Brita–can reduce HAA5 in water.

    Do Ultraviolet (UV) Filters Remove Haloacetic Acids?

    No, UV filters will not remove HAA5. While UV filters may be used as an alternative to chlorine during central water treatment to avoid the creation of HAA5, it will not remove HAA5 already in the water system.[4]

    Does Boiling Water Remove Haloacetic Acids?

    No, boiling water will not reduce HAA5.

    Can Anything Be Done to Prevent HAA5 in Drinking Water?

    Rather than filtering at home, ultimately the safest approach is for utilities to prevent the formation of HAA5 during water treatment by deploying corrective approaches to remove natural materials from water supplies before disinfecting with chlorine, if possible.[5]

    While service providers are required to monitor their treated water for HAA5, several communities have experienced periods of high concentration in their local supplies. Whether you want to test for just HAA5 or are interested in a comprehensive package like Extended City Water Test (which includes HAA5, along with a broad range of potentially dangerous contaminants)–Tap Score can help.

    Every Tap Score report includes a detailed breakdown of all parameters tested and are presented in any easy-to-understand way–along with health-risk analysis, information about common sources, and how your water’s levels compare to a variety of regulatory and public health guideline thresholds. Each report also includes unbiased treatment recommendations tailored to address any issues found in your water. 

    Take a look at an example report here. Have more questions? Send Tap Score a message at and the team of water chemists, treatment experts, and water quality engineers will be able to help!

    Talk to Tap Score

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