Haloacetic acids are a relatively new group of disinfection by-products contaminating our drinking water supplies. As the disinfection process used by municipalities continues to evolve, the importance of understanding haloacetic acids in water will only continue to increase.
We’ll cover everything you need to know about common haloacetic acids like HAA5, including the primary sources, health effects, how to know if your tap water is contaminated, and what filters remove haloacetic acids.
- Haloacetic acids are a group of disinfection by-product compounds that are formed when the chlorine used to disinfect drinking water reacts with naturally occurring organic matter in water.
- Ingesting high levels of haloacetic acids can increase the risk of developing bladder, colon, and rectal cancer, in addition to adverse developmental effects during pregnancy.
- The EPA maximum contaminant level for HAA5 is 60 PPB for public drinking water supplies.
- Reverse osmosis water filters have been shown to be effective at removing haloacetic acids, including the most common HAA5 and other disinfection byproducts.
- The only method to detect haloacetic acids in tap water is to use a certified laboratory test that scans for HAA5 and other common disinfection byproducts.
What Are Haloacetic Acids In Water?
Haloacetic acids (HAA) occur in water as disinfection byproducts (DBP), like trihalomethanes (THMs). These byproducts are produced when the chlorine used to disinfect drinking water reacts with naturally occurring organic matter. Many water treatment plants around the world use chlorination as a viable treatment method to purify water.
Haloacetic acids can be further classified into four groups: HAA3, HAA5, HAA6, and HAA9.
- HAA3: This group inlcudes bromodichloroacetic acid (BrCl2AA), dibromochloroacetic acid (Br2ClAA), and tribromoacetic acid (Br3AA)
- HAA5: This is the most important group to make note of. It consists of monochloroacetic acid (ClAA), monobromoacetic acid (BrAA), dichloroacetic acid (Cl2AA), trichloroacetic acid (Cl3AA), and dibromoacetic acid (Br2AA).
- HAA6: This group represents the sum of HAA5 and bromochloroacetic acid (BrClAA).
- HAA9: The sum of HAA6 and HAA3 make up the HAA9 concentration in water.
All of these compounds are various combinations of chlorine and bromine elements. The most common class of HAAs is HAA5, this is also the only group that is currently regulated by the Environmental Protection Agency (EPA).
How Do Haloacetic Acids Get Into Drinking Water?
As mentioned above, DBPs enter the water supply by sterilizing the water with chlorine. Drinking water disinfection is imperative to remove harmful bacteria and pathogens frequently found in untreated surface water.
Because it’s usually surface water sources like lakes, rivers, or reservoirs that need to be treated, city water systems are more likely to have elevated HAA levels. It’s possible for private water sources or wells to contain HAA, however, it is less likely in groundwater. Much of the time groundwater is purified through soil and rock so chlorination treatments aren’t as vital. Shallow wells or groundwater sources that are frequently treated with shock disinfection should be tested for DBPs.
The concentrations of HAAs in public drinking water will vary based on the amount of time water is spent in the distribution system, the water source, and the disinfectant practices of the treatment plant.
What Are The Effects Of Haloacetic Acids In Drinking Water?
Dichloroacetic acid (DCA) and trichloroacetic acid (TCA) are classed as potential carcinogens by the EPA. The carcinogenicity of each HAA5 has also been measured, in which the other haloacetic acids are classed as “reasonably anticipated to be a human carcinogen” based on results from both animal and human studies.
Consuming high levels of haloacetic acids over an extended period of time increases the risks for:
- Bladder Cancer
- Colon Cancer
- Rectal Cancer
Specifically, there is concern that a lifetime of exposure of HAAs can impact liver and nervous system functioning.
Some evidence suggests that maternal exposure to HAA5 can negatively impact pregnancy outcomes and fetal development.
Researchers are still attempting to figure out how to accurately measure HAA exposure from drinking water. Hopefully, with better data, stronger policies may be put in place to ensure drinking water standards are set at levels where no known adverse health effects occur.
EPA Regulatory Levels For Haloacetic Acids In Drinking Water
The stage 1 and 2 disinfectant byproduct rules (DBPR) are in place to limit exposure to the population. HAA5 are regulated under stage 2. Though the other groups aren’t yet regulated, the fourth unregulated containment monitoring rule (UCMR 4) includes HAA5, HAA6, and HAA9. This rule is in place to keep tabs on and measure potentially harmful contaminants that aren’t yet regulated.
The set maximum contaminent level (MCL) for total HAA5 is 60 µg/L (one µg/L equals one part per billion) for public drinking water supplies. The 2018 Drinking Water Standards and Health Advisories lists figures for the individual HAAs:
- For dichloroacetic acid (DCA), the MCL is 0.06 mg/L, but the MCLG is 0, the DWEL is 0.1 mg/L and the Life-time Limit is 0.03 mg/L.
- For monochloroacetic acid (MCA), the MCL is 0.06 mg/L, but the MCLG is 0.07 mg/L, the DWEL is 0.35 mg/L, and the Life-time Limit is 0.07 mg/L
- For trichloroacetic acid (TCA), the MCL is 0.06 mg/L, but the MCLG is 0.02 mg/L, the DWEL is 1 mg/L, and the Life-time Limit is 0.02 mg/L.
- There are no MCLG for MBA and DBA.
For the HAA9 group, there is currently no legal limit, but this group may face regulation soon. To refresh your memory, this group consists of concentrations of HAA3 and HAA6.
Interestingly, the Environmental Working Group (EWG) provides more conservative recommendations. A level of HAA5 in the drinking water where no adverse health effects are observed after a lifetime of exposure is 0.1 ppb. This is quite different than the legal maximum containment level (MCL) of 60 ppb set by the EPA. For HAA9, the EWG recommended level is 0.06 ppb.
The EWG has collected data on containment concentrations in tap water systems nationwide. According to EWG data, from 2017-2019, people in all 50 states are exposed to HAA5 from the water supply to some extent. Specifically, 285 million people were exposed to amounts over health guidelines and 272,000 were exposed to haloacetic acids above the legal limit.
This is likely why some states like California have implemented public health goals (PHGs) stricter than EPA standards. According to the Office of Environmental Health Hazard Assessment (OEHHA), a PHG is based on carcinogenicity and is set at a level of risk of one additional cancer case per one million persons exposed over a lifetime.
California’s PHGs for HAA5 are:
- 0.2 parts per billion (ppb) for DCA
- 0.1 ppb for TCA
- 0.03 ppb for DBA
- 53 ppb for MCA
- 25 ppb for MBA
How To Detect Haloacetic Acids In Drinking Water
An issue with all DBPs is that there usually isn’t any indication that they are present unless water has a strong chlorine smell. The only way to know for sure if your water contains haloacetic acids is to test a sample of your tap water.
Certified Laboratory Test
The most effective way to determine haloacetic acids in drinking water is to complete a certified laboratory test. With this method, you collect a tap water sample and send it to a certified lab where an expert analyzes the sample for contaminants like haloacetic acids.
I recommend the Freshnss Labs Ultimate Water Test Kit which scans for HAA5, disinfection byproducts, and dozens of other harmful contaminants. The kit includes everything you need to properly collect a water sample and send it to a certified laboratory. Within 3 business days, you receive a detailed report with the exact levels of haloacetic acids detected, any health or plumbing alerts, and the best treatment options based on your data.
Check Water Quality Report
Another way people can monitor contaminants in their water supply is by reading their Consumer Confidence Report (CCR). Public water systems are required to send out these reports to the people served. If levels exceed the EPA’s regulatory levels, citizens will also be notified by their water supplier.
Simply go to the EPA database and search your location by zip code to access your latest report.
Treatment Methods To Remove Haloacetic Acids
If you’ve received a notice that your water supply has elevated HAA levels, you can rest assured knowing that there are filtration methods to either significantly reduce or eliminate the concentration of HAAs in your drinking water.
Catalytic carbon is an effective treatment method to remove haloacetic acids and other disinfection byproducts like chloramines from drinking water. Catalytic carbon can be used in either whole-house or point-of-use filters.
Not to be confused with granular activated carbon (GAC) which are not well suited for disinfection byproducts, catalytic carbon has a reduction capacity almost four times greater for contaminants like HAAs. The filter is made up of organic material (made with carbon) like coconut shells or wood that is activated to be able to adsorb chemicals, in turn removing them from drinking water.
Reverse osmosis (RO) systems can be applied to whole-house, drinking water taps, or as point-of-use systems.
RO is a common water filtration system that removes up to 99.9% of disinfection byproducts in addition to a broad spectrum of other contaminants. This filtration system works by forcefully using water through a semipermeable membrane where clean water passes through and contaminants are left behind.
The downside to RO systems is they use a small amount of wastewater to flush the membrane clean of contaminants. They can also be more expensive than a traditional single-stage carbon filter.
Can Anything Be Done Reduce Exposure To HAA5 In Drinking Water?
Unfortunately, a permanent solution to eliminate HAA5 exposure must be done at the systems level or treatment plant to reduce the chlorine dose. This can be done by limiting the naturally occurring organic matter prior to chlorination.
Frequently Asked Questions
Do Brita filters remove haloacetic acids?
Brita filters may reduce the amount of HAAs in drinking water. However, most Brita filters use activated carbon technology, which is not specifically effective at reducing haloacetic acids in water.
What type of contaminant is haloacetic acids?
Haloacetic acids (HAAs) are a type of disinfection byproduct (DBP) that occur during the reaction between naturally occurring organic matter and chlorine in the water distribution system.
Does boiling water remove HAA5?
No, boiling water does not remove HAA5. In fact, boiling water can increase the concentration of HAA5 in your water.