The Fluoride Shortage Started in a Fertilizer Scrubber
Table of Contents
On 30 July 2026 the shared water treatment plant that serves Lewiston and Auburn, Maine — about 40,000 customers between them — stopped adding fluoride to the drinking water. It had been doing it since 1970, following a 1968 vote. The reason was not a policy change or a council decision. A shipment that was expected in June simply never arrived. Michael Broadbent, superintendent of the Auburn Water and Sewer District, told the local paper he had been at the plant in one role or another for well over a decade: “I’ve never seen this before.”
He is not the only one. Earlier in the year Baltimore, which serves about 1.8 million customers, and WSSC Water, which serves about 1.9 million people in suburban Maryland, both cut the fluoride concentration in their finished water from roughly 0.7 milligrams per litre down to 0.4 — not because anyone decided that was a better number, but to stretch a chemical they could no longer reliably buy. This article is about where that chemical actually comes from, why its supply has almost no slack in it, and why two separate things went wrong in 2026 at the same time. It is a supply-chain story, not a public-health argument: what follows takes no position on whether water should be fluoridated, only on how the molecule that does it is made and moved.
What utilities have actually done
The useful thing about this shortage is that water systems are regulated, public bodies, so they announce what they are doing and why. The pattern across 2026 is consistent: first dose reduction to conserve, then, where deliveries failed outright, suspension.
| System | Population served | Action | Date reported |
|---|---|---|---|
| WSSC Water (Montgomery & Prince George’s counties, MD) | ~1.9 million | Fluoride reduced from ~0.7 to 0.4 mg/L; supplier deliveries cut by about 20% | 7 April 2026 |
| Baltimore City Department of Public Works | ~1.8 million | Fluoride reduced from 0.7 to 0.4 mg/L | April 2026 |
| Lewiston-Auburn, Maine (shared treatment plant) | ~40,000 customers | Fluoridation stopped entirely; first interruption since 1970 | Stopped 30 July 2026 |
“This is a temporary adjustment driven solely by supply availability. We remain committed to maintaining safe, high-quality drinking water and will restore optimal fluoride levels as soon as supply conditions stabilize.”
— Ben Thompson, Director of Production, WSSC Water, 7 April 2026
Roughly 60% of the United States population receives fluoridated water, so the affected share of the country is not marginal. Dan Hartnett, chief policy officer at the Association of Metropolitan Water Agencies, and Matthew Garbark, director of Baltimore’s Department of Public Works, both described a market sourced from a very small pool of producers. That is the part worth explaining, because it is not obvious why a chemical used by most of the country should be so thinly supplied.
Where the fluoride actually comes from
Here is the fact that reframes the whole story: nobody builds a plant to make fluorosilicic acid. It is recovered from the off-gas of fertilizer manufacturing, and the EPA’s own supply-chain profile lays out the chemistry in two steps.
Phosphate rock is mostly fluorapatite, and it carries roughly 3 to 4% fluoride. The primary reaction is the wet process — the same digestion of rock with sulfuric acid that makes phosphoric acid for fertilizer, and that produces an enormous quantity of gypsum as well:
Ca₅(PO₄)₃F + 5 H₂SO₄ → 3 H₃PO₄ + 5 CaSO₄ + HF
During that reaction the fluoride and the silicon in the rock are mobilised and leave as gases: silicon tetrafluoride and hydrogen fluoride. Those vapours are captured, and when they are scrubbed with water the second reaction happens in the scrubber itself:
SiF₄ + 2 HF → H₂SiF₆
Two consequences of being a scrubber product. First, the output is set by how much fertilizer someone else decided to make — not by how much fluoride water systems need. Second, it is not even a clean single compound: the EPA notes, citing AWWA, that fluorosilicic acid “is not a discrete compound, but rather an aqueous mixture of fluorosilicated compounds.” The EPA’s own profile describes the material as forming “as a waste stream” when the gases are scrubbed.
So the chain runs: sulfur becomes sulfuric acid, sulfuric acid digests phosphate rock, the rock gives up its fluoride as gas, the gas is scrubbed into fluorosilicic acid, and a tanker truck takes it to a water treatment plant. Every link in that chain is somebody else’s business decision until the last one.
Why the supply has no slack in it
Four structural facts, each independently sourced, explain why a disruption anywhere in that chain shows up quickly at the tap.
| Structural fact | Figure | Why it matters |
|---|---|---|
| Domestic production is concentrated in very few plants | 3 phosphoric acid plants recovered FSA in 2025; ~45,000 tons | USGS has recorded 40–45,000 tons a year recently, from three plants. There is no fourth plant to lean on |
| It cannot be stockpiled | Shelf life about one month | Buying ahead is not an option. A gap in deliveries becomes an operating decision within weeks |
| Imports are the larger half of supply | 2019: ~29 M kg produced, ~39 M kg imported, ~10 M kg exported | Consumption of roughly 58 M kg leans on imports for well over half the total |
| The certified supplier layer is wide but sits on a narrow base | 103 NSF-60 certified suppliers vs 5 domestic manufacturing locations | Having many certified sellers does not create supply. They are distributing the same few streams |
That last line is the one that fools people. A buyer looking at a long list of certified suppliers reasonably assumes a deep market. But certification is a quality credential, not a manufacturing capability: the EPA counted 103 NSF/ANSI Standard 60 certified suppliers of fluorosilicic acid against five domestic manufacturing locations. Depth of distribution is not depth of supply.
The EPA wrote this down in 2022
This is the part that ought to be better known. In December 2022 the EPA published a supply-chain profile for fluorosilicic acid as part of a series on water-sector chemicals. It assessed the risk of supply disruption and named the mechanism almost exactly as it played out.
“Production of fluorosilicic acid depends on the production of phosphate rock and manufacturing of sulfuric acid. Planned facility downtime at the limited number of domestic manufacturing facilities has resulted in recurring volatility in the supply of fluorosilicic acid.”
— EPA, Fluorosilicic Acid Supply Chain Profile, December 2022
The same document rated the likelihood of disruption as High, noting “previous widespread disruptions in supply that impacted the water sector,” and rated vulnerability as Moderate-High because of “limited domestic manufacturing concentrated in select geographic areas and strong reliance on imports.” The headline risk rating was nonetheless Moderate-Low, because the EPA scored criticality as Low — fluoridation is, in its words, a “discretionary application,” meaning a utility can reduce or stop dosing without the water becoming unsafe to drink. That is exactly what Baltimore, WSSC and Lewiston-Auburn did.
The forecast was right in substance and wrong in trigger. The EPA expected planned facility downtime to be the thing that wobbled supply. What arrived in 2026 was unplanned: an interruption at a major overseas producer, and a wave of curtailments at domestic phosphate plants driven by the price of sulfur. The vulnerability the document identified — too few plants, heavy import reliance, no ability to stockpile — was the correct diagnosis regardless of which shock found it.
Both ends tightened at once
Two independent things happened in 2026, and the reason this shortage is described by water managers as unprecedented is that they happened together.
The import leg. Fluorosilicic acid is mainly produced overseas and imported by US distributors, and in the spring of 2026 production at one of the world’s leading exporters was interrupted when a substantial part of the workforce at a major facility became unavailable. Reporting by NPR and member stations in April traced the US shortage directly to that interruption. It is worth being careful with trade figures here: the EPA notes that import and export data specific to fluorosilicic acid is not available, because it is reported inside a broader customs category for inorganic acids other than hydrogen fluoride. Within that broader category in 2021, the largest exporters were China at 92 million kg and Israel at 40 million kg, with the United States the fourth-largest importer.
The domestic leg. At the same time, the American phosphate industry was curtailing production — and for reasons that have nothing to do with fluoride. Sulfur, which is the dominant cash cost in making sulfuric acid, became expensive enough that converting it into fertilizer stopped making money. By August, Mosaic had curtailed or idled four phosphate facilities: Bartow and Riverview in Florida, and Faustina and Uncle Sam in Louisiana. We covered that decision, and the reason an idled acid plant is unexpectedly hard to restart, in our piece on why those acid plants were switched off rather than broken.
The connection that has gone largely unremarked. Those are not unrelated industries. The EPA’s profile records that domestic fluorosilicic acid manufacture has historically taken place in Florida, Louisiana, North Carolina and Wyoming, by J.R. Simplot, Mosaic and PCS Phosphate — and it identifies the Mosaic phosphoric acid plants in Florida and Louisiana among the sites from which the acid is derived. Three of the four facilities on the August curtailment list — Bartow, Riverview and Uncle Sam — sit in that same small population of phosphoric acid plants. So the domestic fallback for a disrupted import stream was contracting at precisely the moment it was needed. WSSC Water said as much in its April notice, attributing the disruption to both reduced domestic production and lower output from other producers.
One further piece of context makes the fragility plainer. The United States has been 100% net import reliant for fluorspar — the conventional mineral source of fluorine chemistry — for years running, excluding sales from stockpiles. Recovered fluorosilicic acid is genuinely useful here: USGS counts the 45,000 tons recovered in 2025 as equivalent to roughly 73,000 tons of 100% calcium fluoride, and one operation in Aurora, North Carolina makes hydrogen fluoride from it. Domestic fluorine chemistry leans on this scrubber stream more than its reputation as a waste product suggests.
What this means if you buy fluorosilicic acid industrially
Municipal fluoridation is the dominant use of this acid — the EPA puts roughly 63% of domestic consumption in the water sector — but it is not the only one. The same molecule goes into aluminium fluoride and other metal fluorosilicates, hardening masonry and ceramics, metal surface treatment, solar panel and silicon chip production, and hydrogen fluoride manufacture. If you are in one of those industries, you are drawing on the same narrow stream as the water utilities, and you should expect that to show up as lead time rather than as a headline.
Be clear about which market you are in. Chemicals dosed into public drinking water in the United States are normally certified to NSF/ANSI/CAN Standard 60 for that application, and that certification attaches to a specific product from a specific supply chain. If you are a water system, buy against that certification. If you are an industrial user, the question is different and simpler: what does your process actually need, and what documentation does your quality system want with it? Tell us the application and we will tell you what we can supply against it.
For industrial buyers there is a grade question underneath the supply question, and it is the same discipline that applies to any acid bought against a specification. Our 23% technical material and our 23% ACS grade are the same concentration and a different purity conversation: ACS grade is held to reagent-level purity, which matters when trace metals would interfere with a synthesis or an analysis, and is simply an unnecessary cost when it would not. If you want the fuller treatment of strengths, handling and materials compatibility, our guide to hydrofluorosilicic acid uses, grades and safety covers it.
Handling, plainly. Fluorosilicic acid is a strongly corrosive acid that attacks metals and tissue, and it is a fluoride-bearing material, which makes exposure a different problem from a mineral acid burn. The EPA profile notes that exposure to strong oxidisers or elevated temperatures can decompose it and release hydrogen fluoride and hydrogen gas. It wants cool, well-ventilated storage, compatible transfer equipment, and trained operators. Sections 7 and 8 of the safety data sheet for the specific product you receive are where the storage and protective-equipment guidance lives, and they should be read before the drum is opened rather than after.
What we are watching next
- Whether the curtailed phosphate capacity comes back. Domestic fluorosilicic acid recovery is a passenger on phosphoric acid run rates. Restarts at the Florida and Louisiana plants are the leading indicator for the domestic leg.
- The sulfur price. It is the input that decides whether those plants are worth running at all, and therefore whether the scrubbers are running.
- Utility notices rather than trade data. Because the customs category is broader than the product, public dose-reduction notices from water systems are a faster and more honest signal than import statistics.
- Lead times on industrial fluoride chemistry. Aluminium fluoride, fluorosilicates and hydrogen fluoride all draw on the same stream; pressure tends to appear there before it appears in price.
Common questions
Why is there a fluoride shortage for drinking water in 2026?
Two things happened at once. Production at one of the world’s leading overseas producers of fluorosilicic acid was interrupted in the spring of 2026, and imports supply well over half of US consumption. At the same time US phosphate producers curtailed output at plants that also recover fluorosilicic acid, because the price of sulfur made fertilizer production uneconomic. Because the acid has a shelf life of about a month, neither utilities nor distributors could buy ahead of the gap.
Where does the fluoride in tap water come from?
It is a byproduct of phosphate fertilizer manufacturing. Phosphate rock contains about 3 to 4% fluoride. When sulfuric acid digests the rock to make phosphoric acid, the fluoride and silicon leave as silicon tetrafluoride and hydrogen fluoride gas; scrubbing those gases with water produces fluorosilicic acid, which is the compound most US community water systems use.
How many plants make fluorosilicic acid in the United States?
Very few. USGS estimated that 45,000 tons were recovered in 2025 from three phosphoric acid plants processing phosphate rock. The EPA counted five domestic manufacturing locations as of 2017, in Florida, Louisiana, North Carolina and Wyoming, and the number has moved between four and six over the preceding decade.
Why can utilities not just stockpile it?
Fluorosilicic acid has a shelf life of roughly one month under recommended storage conditions, and it is highly corrosive, so holding large inventories is neither practical nor safe. That is why a missed delivery turns into a dose reduction within weeks rather than months.
Is the water safe when fluoride is reduced or stopped?
Reducing or suspending fluoridation does not make water unsafe to drink, which is why utilities were able to use it as their conservation lever. The EPA’s own supply-chain profile classifies the criticality of fluorosilicic acid as low on the grounds that it is a discretionary application. Questions about the dental effects of the change belong to the utilities and public health authorities, and the notices above link to what each system said.
What else is fluorosilicic acid used for besides water fluoridation?
Water fluoridation is the dominant use — the EPA puts roughly 63% of domestic consumption in the water sector — but the same molecule goes into aluminium fluoride and other metal fluorosilicates, hardening masonry and ceramics, metal surface treatment, solar panel and silicon chip production, and hydrogen fluoride manufacture. Those industrial users draw on the same narrow recovered stream, which is why pressure tends to show up there as lead time rather than as a headline.
References & Authoritative Sources
The supply-chain structure, chemistry and risk assessment are from the EPA and USGS; the utility actions are from the utilities and the outlets that reported them; the curtailment facts are from the trade press.
- Fluorosilicic Acid Supply Chain Profile (PDF) — US Environmental Protection Agency, EPA 817-F-22-028, December 2022. The two-step manufacturing chemistry and Figure 1 equations; 3–4% fluoride in phosphate rock; “formed as a waste stream”; “not a discrete compound, but rather an aqueous mixture of fluorosilicated compounds”; one-month shelf life; ~63% of consumption in the water sector; 2019 production 29 M kg, imports 39 M kg, exports 10 M kg, consumption 58 M kg; 103 NSF-60 certified suppliers against 5 domestic manufacturing locations; the risk drivers and the Criticality/Likelihood/Vulnerability ratings; historical producers and states; the caveat that FSA-specific trade data is unavailable.
- Fluorspar — Mineral Commodity Summaries 2026 (PDF) — US Geological Survey. “In 2025, an estimated 45,000 tons of FSA, equivalent to about 73,000 tons of fluorspar grading 100% CaF2, was recovered from three phosphoric acid plants that processed phosphate rock”; the recent 40–45,000 ton series; 100% net import reliance for fluorspar; HF production from FSA at Aurora, North Carolina.
- Toxicological Profile for Fluorides, Hydrogen Fluoride, and Fluorine — Production, Import/Export, Use and Disposal — Agency for Toxic Substances and Disease Registry, September 2003. “Fluorosilicic acid is a byproduct of the action of sulfuric acid on phosphate rock containing fluorides and silica or silicates”; 2001 production of 65,200 tons from 10 plants owned by 6 companies, of which about 41,200 tons were sold for water fluoridation.
- Middle East conflict causes a fluoride shortage for US drinking water — NPR, via OPB, 15 April 2026. The interruption at a leading overseas producer; a market sourced from a small pool of international producers; delivery in 5,000-gallon tanker trucks; Baltimore and WSSC dose reductions; a supplier cutting deliveries by about 20%; roughly 60% of the US population on fluoridated water. Quotations from Matthew Garbark (Baltimore DPW), Dan Hartnett (Association of Metropolitan Water Agencies) and Ben Thompson (WSSC Water).
- WSSC Water Temporarily Reduces Fluoride Levels in Drinking Water Due to Nationwide Supply Chain Disruptions — WSSC Water, 7 April 2026. The 0.7 to 0.4 mg/L reduction for 1.9 million customers; attribution to reduced domestic production as well as lower output from other producers; the Ben Thompson quotation.
- Nationwide shortage forces Lewiston-Auburn to stop fluoridating drinking water — Sun Journal, 12 August 2026. Fluoridation stopped 30 July 2026; fluoridated since 1970 after a 1968 vote; the shipment expected in June that did not arrive; roughly 40,000 customers; the Michael Broadbent quotation; Erica Kidd and Lindsay Hammes (Maine DHHS) on timing.
- Mosaic to further curtail US, Brazil phosphate output — Argus Media, 7 August 2026. The four curtailed facilities: Bartow and Riverview in Florida, Faustina and Uncle Sam in Louisiana.
- The Acid Plants Are Not Broken. They Were Switched Off. — Alliance Chemical, 17 September 2026. Our account of the phosphate curtailments, the sulfur economics behind them, and why an idled sulfuric acid plant does not restart cheaply.
The two we stock
Hydrofluorosilicic Acid 23% (HFS)
The industrial working strength, for metal treatment, fluorosilicate synthesis and masonry hardening.
Hydrofluorosilicic Acid 23% ACS
Same strength, reagent-level purity, for analytical work and synthesis where trace metals interfere.
Industrial fluoride chemistry, and not sure which grade you need?
Tell us the application, the concentration you run today and the container size you receive, and we will tell you whether technical grade does the job or whether the reagent purity is actually buying you something. Tell us what the material has to do and what paperwork has to come with it, and we will tell you what fits — that is the right answer, not the nearest thing in stock.
See fluorosilicic acid grades and sizesKey numbers and sources
| Number | What it is | Source |
|---|---|---|
| 3 plants / 45,000 tons | US fluorosilicic acid recovery in 2025 | USGS MCS 2026 |
| 3–4% | Fluoride content of phosphate rock | EPA 817-F-22-028 |
| ~1 month | Shelf life of fluorosilicic acid | EPA 817-F-22-028 |
| 29 / 39 / 58 M kg | 2019 domestic production / imports / consumption | EPA, from USGS + USITC |
| 103 vs 5 | NSF-60 certified suppliers vs domestic manufacturing locations | EPA 817-F-22-028 |
| 0.7 → 0.4 mg/L | Dose cut at Baltimore (~1.8M) and WSSC Water (~1.9M) | WSSC Water; NPR/OPB |
| 30 July 2026 | Lewiston-Auburn stopped fluoridating; fluoridated since 1970 | Sun Journal |
Frequently Asked Questions
Why is there a fluoride shortage for drinking water in 2026?
Two things happened at once. Production at one of the world's leading overseas producers of fluorosilicic acid was interrupted in the spring of 2026, and imports supply well over half of US consumption. At the same time US phosphate producers curtailed output at plants that also recover fluorosilicic acid, because the price of sulfur made fertilizer production uneconomic. Because the acid has a shelf life of about a month, neither utilities nor distributors could buy ahead of the gap.
Where does the fluoride in tap water come from?
It is a byproduct of phosphate fertilizer manufacturing. Phosphate rock contains about 3 to 4% fluoride. When sulfuric acid digests the rock to make phosphoric acid, the fluoride and silicon leave as silicon tetrafluoride and hydrogen fluoride gas; scrubbing those gases with water produces fluorosilicic acid, which is the compound most US community water systems use.
How many plants make fluorosilicic acid in the United States?
Very few. USGS estimated that 45,000 tons were recovered in 2025 from three phosphoric acid plants processing phosphate rock. The EPA counted five domestic manufacturing locations as of 2017, in Florida, Louisiana, North Carolina and Wyoming, and the number has moved between four and six over the preceding decade.
Why can utilities not just stockpile it?
Fluorosilicic acid has a shelf life of roughly one month under recommended storage conditions, and it is highly corrosive, so holding large inventories is neither practical nor safe. That is why a missed delivery turns into a dose reduction within weeks rather than months.
Is the water safe when fluoride is reduced or stopped?
Reducing or suspending fluoridation does not make water unsafe to drink, which is why utilities were able to use it as their conservation lever. The EPA's own supply-chain profile classifies the criticality of fluorosilicic acid as low on the grounds that it is a discretionary application. Questions about the dental effects of the change belong to the utilities and public health authorities, and the notices above link to what each system said.
What else is fluorosilicic acid used for besides water fluoridation?
Water fluoridation is the dominant use — the EPA puts roughly 63% of domestic consumption in the water sector — but the same molecule goes into aluminium fluoride and other metal fluorosilicates, hardening masonry and ceramics, metal surface treatment, solar panel and silicon chip production, and hydrogen fluoride manufacture. Those industrial users draw on the same narrow recovered stream, which is why pressure tends to show up there as lead time rather than as a headline.
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