Diquat
Overview
An herbicide used on land and in water bodies.
In Florida, Diquat was found in 5 community water systems serving about 3,715 people. It was measured by 1,559 systems in all, so it was detected in under 1% of the systems that tested for it.
The highest reading relative to the limit was at Paradise Park Condo. Assoc. in Charlotte County, at 2% of it.
Where it comes from: Runoff from herbicide use.
The standards
Enforceable. A utility must stay at or under this.
Health-based, not enforceable. Often lower than the limit, sometimes zero.
California OEHHA PHG (2016).
Health effects the EPA associates with it: Cataracts.
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 reduces it, though it is water-soluble enough that carbon works less efficiently here than against oily compounds. Reverse osmosis alongside carbon is the surer combination.
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
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.