Where It Comes From
Decaying plants and soils, algae, wetlands/peat, stormwater and wastewater runoff; levels often rise after heavy rains or wildfires [1][2].
How You Are Exposed
Mainly by drinking tap water. In chlorinated water with high DOC, DBPs can be taken in by drinking, inhaled during showers, and absorbed through skin while bathing or swimming [2][3].
Why It Matters
DOC makes water darker and can cause taste/odor issues, and it increases DBP formation. EPA limits DBPs and requires treatment to remove total organic carbon (TOC) to reduce them [1].
Who Is at Risk
People on surface-water supplies with high color/tannins, during runoff events; communities relying on chlorine; pregnant people, infants, and frequent pool users may be more sensitive to DBPs [2][3].
How to Lower Your Exposure
Check your water utility’s Consumer Confidence Report for TOC/DBPs; use NSF-certified activated carbon or reverse osmosis filters; run cold water and ventilate during showers; maintain and flush private wells after disinfection [1][2].
References
- [1]US EPA. Disinfectants and Disinfection Byproducts Rules (DBPRs). https://www.epa.gov/dwreginfo/disinfectants-and-disinfection-byproducts-dbpr-rules
- [2]WHO. Guidelines for Drinking-water Quality, 4th ed. https://www.who.int/publications/i/item/9789241549950
- [3]CDC. Trihalomethanes (THMs) Factsheet. https://www.cdc.gov/biomonitoring/Trihalomethanes_FactSheet.html