When people say "fluoride is added to the water", in most large Australian plants they mean hydrofluorosilicic acid (H2SiF6, also called fluorosilicic acid).
Where it comes from
According to the NHMRC's Australian Drinking Water Guidelines, it is a by-product of making fertiliser from phosphate rock. When the rock is treated with sulfuric acid, fluoride gases are released and captured in water, producing the acid. It's supplied at up to 30% strength and usually dosed from a 20% stock solution.
Australian suppliers include Ixom and CSBP in WA. In 2010, SA Water told Parliament it was sourcing supply internationally.
Impurities
Because it comes from phosphate rock, the acid can contain trace contaminants including arsenic and lead, depending on the source rock. The rules require that dosing must not push any contaminant above Drinking Water Guideline values. NSW's Code of Practice notes metals are the main impurities of concern and "vary significantly" in this acid.
The standards it must meet
- NSW requires utilities to use a purchasing specification, with the American Water Works Association standard AWWA B703 as a minimum.
- B703 refers to NSF/ANSI/CAN 60 for health effects of treatment chemicals.
- US testing reported by the CDC found 57% of fluoride additive samples had no detectable arsenic.
Why this matters
Supporters point out that the finished water is tested and the trace levels are tiny. Critics argue a pharmaceutical-grade compound would be more appropriate than an industrial by-product. Both sides agree on one thing: the system relies on testing every batch. We are asking state health departments how often batches are independently tested, and will publish the answers.