Do Berkey Filters Reduce Haloacetic Acids and Trihalomethanes?

Yes, see test results

What are Haloacetic Acids and Trihalomethanes?

Tap water is cleaned by municipalities before it ever reaches your house. There are a few different ways to treat water and one of the most common methods is using chlorine. It is proven to being effective at killing waterborne contaminants. Despite its wide use and powerful abilities, chlorine has some negative attributes, one of them being its disinfectant by products (DBPs), such as haloacetic acids and trihalomethanes.

haloacetic acid molecules

Haloacetic Acids (HAA5)

Haloacetic acids refer to the molecules in the acetic acid molecule (C2H4O2) where the hydrogen atoms that are attached to a carbon atom, are replaced by a halogen. A halogen is an element in in Group 17 on the periodic table of elements: chlorine, bromine, fluorine and iodine. 

  • Monobromoacetic acid (C2H3Br1O2) is one bromine atom replacing one hydrogen atom in an acetic acid molecule.
  • Monochloroacetic acid (C2H3Cl1O2) is one chlorine atom replacing one hydrogen atom in an acetic acid molecule.  
  • Dibromoacetic acid (C2H2Br2O2) is two bromine atoms replacing two hydrogen atoms in an acetic acid molecule. 
  • Dichloroacetic acid (C2H2Cl2O2) is two chlorine atoms replacing two hydrogen atoms in an acetic acid molecule.
  • Trichloroacetic acid (C2H1Cl3O2) is three chlorine atoms replacing three hydrogen atoms in an acetic acid molecule.

The hydrogen atoms react with organic material in water to create the various different haloacetic acids. Since most potable water is treated with disinfectants containing chlorine, haloacetic acids are prevalent. They are more present in water that originates from surface water, such as rivers, lakes, and streams because there's more organic material, therefore more to disinfect and more to react with. 

Trihalomethanes (THM)

Trihalomethanes (CHCl3) are chemical compounds in when three of the four hydrogen atoms of methane (CH4) are replaced by a halogen atom. Chlorine, bromine, fluorine, and iodine are are halogen atoms. The replacement of atoms happens when methane compounds react with water that has chlorine or other halogen elements in it. Water treatment plants often use chlorine to disinfect water. These byproducts occur more often when there is a higher amount of inorganic and organic material.

  • Trichloromethane (CHCl3) also known as chloroform is three chlorine atoms replacing three hydrogen atom.
  • Dibromochloromethane (CHClBr2) is two bromine atoms replacing two hydrogen atoms.
  • Bromodichloromethane (CHCl2Br) is the hydrogen atoms are replaced by one bromine atom and two chlorine atoms.
  • Tribromomethane (bromoform) (CHBr3) is three bromine atoms replacing three hydrogen atoms.

Health Risks Caused by Haloacetic Acids and Trihalomethanes

The adverse affects of consumption or absorption of HAA5 and Trihalomethanes are most apparent over long periods of time of high concentrations. THM levels tend to increase with pH, temperature, time, and the level of material present in the water. 

The Maximum Contaminant Level (MCL) for HAA5 is 60 µg/L (one µg/L equals one part per billion). This MCL is for the five HAAs added together.

The Maximum Contaminant Level for Total Trihalomethanes is 80 µg/L.


Cancer At high level of these compounds in drinking water the likelihood of cancer increases. The effects of these are still being studied but preliminarily the EPA identified dichloroacetic acid and trichloroacetic acid to be highest likelihood of being cancerous. Exposure to disinfectant byproducts, including HAA5, increased the incidence of bladde