Haloacetic Acids (HAA5)
Overview
Haloacetic acids are disinfection by-products, formed when chlorine reacts with natural organic matter in the water. They are reported as the sum of five regulated acids (HAA5).
In Florida, Haloacetic Acids (HAA5) was found in 1,298 community water systems serving about 20,744,216 people. 35 of those readings were above the federal legal limit, together serving 223,476 people.
The highest reading relative to the limit was at Sunshine Meadows in Palm Beach County, at 451% of it.
Where it comes from: By-product of drinking-water chlorination.
The standards
Enforceable. A utility must stay at or under this.
Health-based, not enforceable. Often lower than the limit, sometimes zero.
Nobody has published a health goal for haloacetic acids as a total. California has published one for each acid the totals count: dibromoacetic acid 0.03 ppb, trichloroacetic acid 0.1 ppb, dichloroacetic acid 0.2 ppb, monobromoacetic acid 25 ppb and monochloroacetic acid 53 ppb, all issued 2022. Florida Water Report reads the total against the strictest of them. EPA's own health goal for dichloroacetic acid is zero. Source: California State Water Resources Control Board, MCLs, DLRs and PHGs for Regulated Drinking Water Contaminants, updated September 2025.
Health effects the EPA associates with it: May increase the risk of cancer.
The health goal is set on health alone. The legal limit is set as close to it as is technically and economically feasible, so treatment cost and available technology are written into the number a utility is measured against. A system at or under the limit is meeting the standard it is required to meet. Both numbers are shown so the distance between them is visible.
What removes it
Activated carbon, the same as trihalomethanes, which these almost always accompany. Unlike trihalomethanes these are not volatile, so shower exposure is not the concern and a carbon filter at the drinking tap addresses most of the exposure. A softener does nothing for them.
Treatment guidance describes the methods generally used for this contaminant. What your own tap actually carries depends on your plumbing and your service line as much as on the utility, which is what a test at the house tells you and an annual report cannot.
Where in Florida
Highest reported levels
Showing the 25 highest of 1,298 systems that reported Haloacetic Acids (HAA5).
Data Sources
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.