Trihalomethanes are disinfection by-products. They form when the chlorine used to keep water safe reacts with natural organic matter in the water. Utilities balance enough disinfection to kill germs against keeping by-products low.
In Florida, it was reported by 1,329 community water systems serving about 21,273,042 people. 58 of those readings were above the federal legal limit, together serving 571,024 people.
The highest reading relative to the limit was at Sunshine Meadows in Palm Beach County, at 437% of it.
Where it comes from: By-product of drinking-water chlorination.
Enforceable. A utility must stay at or under this.
Health-based, not enforceable. Often lower than the limit, sometimes zero.
California has not published a PHG for this substance.
Health effects the EPA associates with it: May increase the risk of cancer. Liver, kidney, or central nervous system effects.
Water at or under the legal limit meets federal safety standards. A reading above a health goal is not the same as being unsafe, and health goals are set purely on health without regard to cost or treatability. Both are shown so the margin is visible either way.
Showing the 25 highest of 1,329 systems that reported Total Trihalomethanes (TTHM).
These figures describe water as delivered by each utility, not what your home’s plumbing adds after it arrives. Informational; not a substitute for testing your own tap.