Fluoride in Soddy-Daisy’s water: two systems, two answers
Soddy-Daisy doesn’t have one fluoride answer — it has two, because two different water systems serve the area and they made opposite decisions. Here’s each system’s status, its measured level, and what it means for toothpaste, kids’ brushing, and treatments at the dentist.
It depends on your address. Soddy-Daisy is served by two water systems with opposite fluoride policies: Hixson Utility District fluoridates its water — 0.738 mg/L on average — while Northwest Utility District-SD hasn’t added fluoride since July 2016 and measures 0.33 mg/L of naturally present fluoride. Check the name on your water bill — that’s the answer.
Water quality in Soddy-Daisy
Curious about your tap water? Tennessee Water Authority has the full Soddy-Daisy water quality guide — contaminant data, utility details, and filter recommendations.
Why this page never gives one citywide number: any source that tells you flatly “Soddy-Daisy is fluoridated” or “Soddy-Daisy isn’t fluoridated” is wrong for half the town. Everything below is stated per system, with each district’s own report behind it. Two smaller districts — Union Fork-Bakewell UD and Walden’s Ridge UD — also serve parts of the wider area; their fluoride status was not verified for this page, so we publish no figure for them.
Two systems, side by side
Hixson Utility District is the primary system for the Soddy-Daisy area and pumps its own groundwater. Northwest Utility District-SD serves the Soddy-Daisy town core. Same town, opposite fluoride policies — here is each one, from its own 2025 water quality report.
Hixson Utility District
System TN0000303 · Groundwater · Primary system for the Soddy-Daisy area
0.738 mg/L
Average of quarterly compliance testing in the district’s 2025 water quality report, with a measured range of 0.58–0.84 mg/L. The district adds fluoride and monitors it daily — and at 0.738 mg/L, the delivered level sits essentially right on the CDC’s 0.7 mg/L target.
Northwest Utility District-SD
System TN0000169 · Serves the Soddy-Daisy town core
0.33 mg/L
Average in the district’s 2025 water quality report, range 0.30–0.36 mg/L. This is not an added dose: the district’s board voted 6–1 in July 2016 to halt fluoride injection, and none has been added since. The 0.33 mg/L is fluoride the report measures as naturally present in the water.
Both levels, next to the benchmarks that matter
Three different federal numbers get mixed up in every fluoride argument — a recommendation, a cosmetic guideline, and a legal ceiling. They are not interchangeable, and each Soddy-Daisy system should be judged against them separately.
| What | Level | What it means |
|---|---|---|
| Hixson Utility District2025 water quality report — average of quarterly compliance testing; range 0.58–0.84 mg/L | 0.738 mg/L | A system that adds fluoride, delivering essentially the CDC’s target level. If Hixson serves your address, your water is fluoridated. |
| Northwest Utility District-SD2025 water quality report — average; range 0.30–0.36 mg/L | 0.33 mg/L | A system that does not add fluoride — none since the board’s July 2016 vote. This figure is naturally present/residual fluoride measured in a non-adjusting system, about half the CDC target. |
| CDC recommended levelU.S. Public Health Service / CDC, since 2015 | 0.7 mg/L | The target for systems that adjust fluoride — judged to prevent cavities while keeping fluorosis risk low. A recommendation, not a law. Hixson sits essentially at it; Northwest UD, by its board’s choice, does not aim for it. |
| EPA secondary standard (SMCL)EPA — not federally enforceable | 2.0 mg/L | A guideline aimed at preventing tooth discoloration (fluorosis). Systems above it must notify the public, but it is a cosmetic-effects standard, not a health-based limit. Both Soddy-Daisy systems are well under it. |
| EPA maximum contaminant level (MCL)EPA — enforceable | 4.0 mg/L | The legal ceiling for fluoride in public drinking water, set to protect against bone disease and severe tooth damage. Both systems are far below it — Hixson at under a fifth, Northwest UD at under a twelfth. |
Sources: Hixson Utility District, 2025 Water Quality Report (PDF); Northwest Utility District-SD, 2025 Water Quality Report; CDC community water fluoridation recommendation; EPA secondary drinking water standards and fluoride MCL.
Which system serves me?
This is the one step that decides everything else on this page, and it takes about thirty seconds.
- Read your water bill. The district named on the bill is the system that serves your address. There are two names to look for: Hixson Utility District and Northwest Utility District-SD.
- If your bill says Hixson Utility District: your water is fluoridated — 0.738 mg/L on average, essentially at the CDC target. The toothpaste and varnish advice below applies in its “routine” form.
- If your bill says Northwest Utility District-SD: your water has not been fluoridated since July 2016. The 0.33 mg/L in it is naturally present, and the advice below leans harder on toothpaste and in-office fluoride for your household.
- No bill in your name? If you rent, ask your landlord or property manager which district bills the property. If your bill names a different district entirely (Union Fork-Bakewell UD or Walden’s Ridge UD serve parts of the wider area), that district’s own water quality report is the document to check — we have not verified those two systems’ fluoride status, and this page won’t guess at it.
What the split means for your routine
The good news: most of the practical advice is the same on both sides of the line, because drinking water was never the main event. Where the two systems genuinely differ, we say so.
01 Toothpaste is the main event — for everyone
Think of it as two different jobs. The water is background exposure — a low level of fluoride in your mouth all day, every time you take a sip. Toothpaste is the concentrated dose, applied directly to your teeth twice a day while you brush — and it does most of the work either way.
For Hixson households, the water backs that up at nearly the CDC target. For Northwest UD households, there’s no added fluoride behind the toothpaste at all — so don’t switch to a fluoride-free paste on the theory that “the water has it covered.” On the Northwest side of town, it doesn’t.
02 Kids: the amount is what changes
Per the ADA, start fluoride toothpaste when the first tooth comes in — the dose, not the ingredient, is what changes with age:
Under age 3: a smear the size of a grain of rice.
Age 3 and up: a pea-size amount.
Brush twice a day, teach them to spit and not swallow, and supervise — an adult should be the one loading the brush, so the pea-size rule is actually followed. This guidance is identical for both systems.
03 In-office varnish: worth more on one side of town
Northwest UD households: varnish is worth more to you. With no added fluoride in your water since 2016, a concentrated fluoride treatment painted on at the dental office has a real gap to fill — most of all for cavity-prone kids and adults: anyone with a pattern of new cavities, braces trapping plaque against enamel, dry mouth (a side effect of many common medications), or exposed roots from gum recession.
Hixson households: with your water near the CDC target, varnish is a routine, risk-based call — genuinely useful for the same higher-risk situations above, less necessary for a mouth with no cavity history. Either way, it’s fair to ask what risk factor the treatment is aimed at.
04 The bigger picture
For how fluoride works, what the recent IQ studies actually found, fluorosis, and the fluoride-free toothpaste question, read our full guide — it keeps the evidence and its limits separate, the same way this page does.
On a private well?
Well water isn’t fluoridated — test first
If your home is on a private well, neither system’s numbers apply to you. No utility adds fluoride to your water, tests it, or reports on it. Natural fluoride in well water varies widely — some wells have almost none, some land near the recommended level, and a few naturally run high.
Have your water tested by a certified laboratory first (your county health department can point you to one). Then take the result to your child’s dentist or pediatrician: fluoride supplements are recommended only when the water is low, in a dose matched to the measured level and your child’s age, and only with professional advice. Never start supplements on a guess — testing is also the only way to catch the opposite problem, a natural level high enough to risk fluorosis while teeth are forming.
Confirm it yourself
Don’t take our word for it — including this page’s. Here are the primary sources behind every figure above:
- Hixson’s 2025 water quality report. The 2025 Water Quality Report (PDF) is the source for the 0.738 mg/L average and the 0.58–0.84 mg/L range — the average of the district’s quarterly compliance testing.
- Northwest UD’s 2025 water quality report. Northwest Utility District-SD’s 2025 Consumer Confidence Report is the source for its 0.33 mg/L average and 0.30–0.36 mg/L range — the level its water carries with no fluoride added.
- CDC’s My Water’s Fluoride. Look your system up in the CDC’s My Water’s Fluoride database, built on state-reported data. It isn’t real-time, so if it ever disagrees with a fresh utility report, trust the report.
- Check the name on your water bill. In Soddy-Daisy this step matters more than anywhere: Hixson Utility District and Northwest Utility District-SD give opposite answers, and the bill is what tells you which one is yours.
Questions Soddy-Daisy readers actually ask
It depends on which system serves your address — Soddy-Daisy has two, with opposite policies. Hixson Utility District (TN0000303) fluoridates its water: 0.738 mg/L on average in its 2025 water quality report. Northwest Utility District-SD (TN0000169), which serves the Soddy-Daisy town core, has not added fluoride since July 2016, when its board voted 6–1 to halt fluoride injection; its 2025 report measures 0.33 mg/L of naturally present fluoride. The name on your water bill tells you which answer is yours.
There are two honest numbers, one per system. Hixson Utility District: 0.738 mg/L on average (range 0.58–0.84 mg/L), the average of quarterly compliance testing in its 2025 water quality report — essentially at the CDC’s recommended 0.7 mg/L. Northwest Utility District-SD: 0.33 mg/L on average (range 0.30–0.36 mg/L) in its 2025 report — fluoride that is naturally present in a system that does not add any. For reference, the EPA’s secondary standard is 2.0 mg/L and its enforceable maximum is 4.0 mg/L; both systems are far below both.
In July 2016, Northwest Utility District-SD’s board voted 6–1 to halt fluoride injection into its water supply, and the district has not added fluoride since. Local reporting at the time said the district’s manager proposed ending fluoridation over damage the process was doing to equipment. What remains in the water — 0.33 mg/L on average in the district’s 2025 report — is fluoride that occurs naturally, not an added dose.
Check your water bill — the district named on it is your system. If it says Hixson Utility District, your water is fluoridated at about 0.738 mg/L. If it says Northwest Utility District-SD, your water has not been fluoridated since July 2016 and carries about 0.33 mg/L of naturally present fluoride. If you rent and never see a bill, ask your landlord or property manager which district bills the property.
Yes — whichever system serves you. Fluoridated water is background exposure, a low level in your mouth throughout the day; fluoride toothpaste is the concentrated dose applied directly to your teeth twice a day, and it does most of the work either way. For Hixson customers the water backs the toothpaste up at nearly the CDC’s target level. For Northwest UD customers, with no added fluoride in the water, the toothpaste matters even more — this is not the place to switch to a fluoride-free paste.
It depends on your system and your cavity risk. For Northwest UD households — no added fluoride in the water since 2016 — varnish is worth more: it’s a concentrated fluoride treatment painted on at the dental office, and it has a real gap to fill, especially for cavity-prone kids and adults. For Hixson households, with water near the CDC target, varnish is a routine, risk-based call: most valuable for anyone with a pattern of new cavities, braces, dry mouth, or exposed roots. Either way, it’s fair to ask what risk factor it’s aimed at.
Sources & method
- Hixson Utility District — 2025 Water Quality Report (PDF), system TN0000303: fluoride 0.738 mg/L average of quarterly compliance testing, range 0.58–0.84 mg/L; groundwater system; fluoride monitored daily.
- Northwest Utility District-SD — 2025 Consumer Confidence Report, system TN0000169: fluoride 0.33 mg/L average, range 0.30–0.36 mg/L, with no fluoride added.
- Northwest UD cessation, July 2016 — contemporaneous local reporting on the district board’s 6–1 vote to halt fluoride injection, and on Hixson Utility District’s board voting in the same period to keep fluoridating.
- CDC — community water fluoridation recommended level, 0.7 mg/L; My Water’s Fluoride system lookup.
- U.S. EPA — fluoride maximum contaminant level (MCL) 4.0 mg/L (enforceable) and secondary standard (SMCL) 2.0 mg/L (non-enforceable guideline for tooth discoloration).
- American Dental Association — children’s fluoride toothpaste amounts (rice-grain smear under age 3, pea-size from age 3) and the recommendation for fluoride toothpaste alongside fluoridated water.
Method in one line: every figure on this page comes from the two districts’ own 2025 reports and the federal benchmarks cited above — nothing estimated, and the two systems are never merged into a single citywide claim. Where we could not verify something (the fluoride status of Union Fork-Bakewell UD and Walden’s Ridge UD, which serve parts of the wider area), the page says so instead of filling the gap.
Want the full picture — how fluoride works, the research debate, fluorosis, and fluoride-free alternatives? Read the complete fluoride guide.