All public water systems in America are required to disinfect the water they supply to the public to remove bacteria, fungi and other pathogens. To do this job, they use chlorine or chloramines (a combination of chlorine and ammonia). Without this disinfection, some people could become sick or even die after ingesting microorganisms in the water.
While disinfection and prevention of disease is vital, this process adds disinfection byproducts to the water supply. Some experts and public health advocacy groups feel that these disinfection byproducts present their own dangers. It is a good idea to get educated about these disinfection byproducts and then to find out how much of them are present in your own community water.
Frequently Asked Questions about These Disinfection Byproducts
- What disinfection byproducts are formed during community water disinfection? There are four: chloroform, bromodichloromethane, bromoform, and dibromochloromethane. Altogether, these are referred to as trihalomethanes or THMs.
- How do they get into the water? They are formed from the interaction of disinfectants and bromide (a naturally occurring substance) or decaying organic material such as plant matter.
- Why is there a concern about trihalomethanes in city water? When there is long-term exposure to high levels of THMs in city water, adverse health effects can occur.
- Can THMs be removed from city water? Yes, there are a few ways to remove THMs. The one most accessible to consumers is activated carbon filtration. Water treatment facilities have other advanced methods of removing these chemicals from water supplies.
Concerns About High Trihalomethane Levels in Community Water
Both the Environmental Protection Agency and World Health Organization have expressed their concerns about levels of these disinfection byproducts in community water supplies around the world. The EPA has set limits on the quantity of these four THMs that may be present in water supplies.
Total Trihalomethanes (TTHM): Total trihalomethanes refers to the total quantity of all four trihalomethanes. According to the EPA, there should be no more than 80 parts per billion in community water.
Other organizations have set much lower standards for THM in city water. The State of California established the following public health goals for these chemicals to protect the health of the public:
- Chloroform: 0.4 parts per billion
- Bromoform: 0.5 parts per billion
- Bromodichloromethane: 0.06 parts per billion
- Dibromochloromethane: 0.1 parts per billion
According to the State of California, a public health goal refers to a standard that is ideal, if cost or other factors do not need to be taken into consideration.
The Environmental Working Group (EWG), a public advocacy organization, also set a standard for total trihalomethanes in water of 0.15 parts per billion, vastly lower than the standard set by the EPA. The EWG recommends the same low levels for individual THMs as those recommended by the State of California.
How Many States Have Found Excessive Levels of TTHM in Their Water?
Thirty-six states have found higher levels of TTHM in their water than the 80 parts per billion recommended by the EPA. In some Louisiana communities, Total THM levels were found as high as 330 parts per billion, more than four times the limit set by the EPA. At least eight different Louisiana water systems exceeded 200 parts per billion between 2017 and 2019, along with one from Oklahoma and one from Florida.
All 50 states have found higher levels of TTHM in their water than the 0.15 parts per billion recommended by the EWG.
Possible Health Effects of Being Exposed to Trihalomethanes
- Cancer: Long-term exposure to high levels of THMs is associated with a higher risk of bladder and colorectal cancers.
- Reproductive harm: Some scientific data indicate that elevated levels of THMs can harm pregnant women and pose risks to fetal development.
- Liver and kidney damage: In animal studies, liver and kidney damage resulted from exposure to high levels of THMs.
- Nervous system: Very high levels of exposure to THMs in animal studies have resulted in central nervous system depression.
- Cardiac effect: Animal toxicity studies have detected cardiac depression and arrhythmias.
- The International Agency for Research on Cancer has classified bromodichloromethane as a possible human carcinogen.
Exposure to THMs can occur by drinking community water with these disinfection byproducts or by showering or swimming in the water.
Removing Trihalomethanes from Your City Water Supply
Trihalomethanes can be removed from your household water by utilizing a reverse osmosis or activated charcoal water filtration system. Before investing in a water filtration system, however, it is wise to obtain a complete profile of any contaminants in your community water so you can choose the most appropriate water filter for your home. Choose ETR Labs’ Premium Water Test to find out the level of all four THMs in your community water supply!