A fluoride reduction claim is easiest to compare across brands when the document shows the fluoride level fed to the system, the level that came out, how much water had already passed through, and the line the result was judged against. For an under-sink reverse osmosis system documented that way, the Viomi B6W is a strong choice, since its SGS test report records fluoride with a new filter and again after 7,300 liters. Other brands publish fluoride evidence in different formats: AquaTru prints a fluoride row on the performance data sheet for its Classic countertop RO system, and A.O. Smith's AORO-50 carries "Fluoride Reduction" on its NSF listing.
Each format answers part of the question, and reading them field by field shows which part. The broader roundup of water filter brands for fluoride removal covers the technologies and product categories, while a separate look at RO systems with published PFAS, fluoride and microplastics data sets fluoride beside other targets.
The Fields That Make a Fluoride Result Comparable
The table places the Viomi B6W's SGS results beside the AquaTru Classic's data sheet entries, one field per row. Both documents use mg/L, and both use NSF/ANSI 58 as the reference for their test design.
| Field | Viomi B6W, new filter | Viomi B6W, after 7,300 liters | AquaTru Classic data sheet |
|---|---|---|---|
| Fluoride fed to the system | 8.906 mg/L, measured | 8.869 mg/L, measured | Challenge set at 8 mg/L, plus or minus 10% |
| Fluoride measured in the product water | 0.240 mg/L | 0.525 mg/L | Not printed as a single value |
| Reduction | 97.31% | 94.08% | 91.8% minimum, 93.5% average |
| Highest product-water level allowed | 1.0 mg/L | 1.0 mg/L | 1.5 mg/L |
| Point in the test | Start of filter use | After 7,300 liters (about 1,928 US gallons) | Summarized across the test as a minimum and an average |
| Equipment the figures describe | Tested unit VM-BU-B6W-US, run at 2.2 liters per minute | Same unit | Models AT2000, AT2010, AT2020, AT2030, AT2040 and AT2050 |
| Replacement schedule printed with the system | RO filter every 24 months, PPC filter every 12 months | Same schedule | RO membrane AT2002 every 24 months or 1,200 gallons, whichever comes first |
The two kinds of entry are written differently. The Viomi B6W columns print measured values, an inlet, an outlet and the percentage between them, at each of two volumes. The AquaTru column states the reduction as a minimum and an average across its test, alongside the specified challenge and the pass line. Reading across a row compares like with like where the field holds the same kind of number: the pass-line row compares two limits, and the reduction row compares a measured percentage with a minimum and an average.
One detail in the first row is worth keeping. The AquaTru figure is a specified challenge range, 7.2 to 8.8 mg/L, while the Viomi B6W figures are the inlet levels the laboratory measured, 8.906 and 8.869 mg/L. Both describe spiked water near 8 to 9 mg/L, written in two different ways.
How the Reduction Percentage Is Calculated
A reduction percentage is derived from the two concentrations beside it, so it can be recomputed in a few seconds. The SGS report states its formula as the influent concentration minus the product water concentration, divided by the influent concentration, times 100%.
For the Viomi B6W's new-filter result, (8.906 − 0.240) ÷ 8.906 × 100 gives 97.31%. After 7,300 liters, (8.869 − 0.525) ÷ 8.869 × 100 gives 94.08%. Both match the printed figures, and the inputs say more than the percentage alone, because the same percentage describes a different glass of water when the starting level is different.
That is the reason to carry the outlet concentration into any comparison wherever a document prints one. Two results can share a percentage while one started from a higher fluoride level, and the measured outlet figure shows where that tested water landed.
Test Volume and Replacement Schedule, Side by Side
A result measured after a stated volume and a replacement schedule are two different fields, and a good record lets a reader see both. The Viomi B6W's second SGS test point is 7,300 liters, about 1,928 US gallons at NIST's 3.785412 liters per gallon. Its replacement schedule is set separately, with the RO filter every 24 months and the PPC filter every 12 months, and the Viomi app shows filter life and sends replacement reminders as each date approaches.
Fluoride is also among the SGS-tested targets of the Viomi V6 PRO and Viomi V8 PRO, two tankless systems whose LED smart faucets show filter life at a glance.
For orientation, a household drawing 2 gallons of RO water a day, an example figure, uses 1,460 gallons over 730 days, roughly two years. Writing that number beside the 1,928-gallon test point puts the household's own volume and the report's volume in the same unit, which makes the record easier to read.
The AquaTru Classic sheet expresses its schedule as a pair of limits: the RO membrane, part AT2002, is replaced "every 24 months or 1200 gallons, whichever comes first." At the same example of 2 gallons a day, 1,200 gallons arrive at about 600 days, a few months before the 24-month mark, so in that example the gallon limit sets the date.
Operating Conditions Written Into a Data Sheet
A performance data sheet can carry three different volume or rate figures, and they answer different questions. On the AquaTru Classic sheet, the operating parameters list a rated flow of 0.06 gallons per minute and a daily production rate of 54 gallons per day, which describe how fast the system makes water. The membrane's 1,200-gallon limit describes when the part is replaced. Neither figure is a fluoride test point. The Viomi B6W's SGS report, for comparison, records its fluoride results at 0 and 7,300 liters, a test volume, at a flow of 2.2 liters per minute.
The same AquaTru section also sets the water the system is meant to receive: a temperature range of 39 to 100°F and inlet limits that include 1,500 mg/L of total dissolved solids and 10 grains per gallon of hardness. These are conditions for the product's use, printed next to the performance claims, and they sit in the record beside the fluoride row rather than inside it.
A 54-gallon-per-day production rate says nothing about how many gallons the fluoride figure was measured at, and a 7,300-liter test point says nothing about how fast water comes out of the faucet.
Pass Lines Inside the Document and on Your Water Report
Pass lines inside a filter document are test conditions: the highest fluoride level the product water could carry while the system treated water spiked to about 8 to 9 mg/L. In the two documents here, that line is 1.0 mg/L in the Viomi B6W's SGS report and 1.5 mg/L for the fluoride claim on the AquaTru sheet. A water report uses a different kind of number, the regulatory limit a utility reports against, which for fluoride is the EPA's maximum contaminant level of 4.0 mg/L. Keeping the test line and the regulatory limit on separate lines stops one from being read as the other.
A utility's report value and a household's own lab result are separate from both of those. Houston's 2025 water quality report, for example, lists "Fluoride (ppm)" in a table whose "Highest Level Allowed (EPA's MCL)" column shows 4, followed by a detections column with minimum, average and maximum values. Because 1 ppm equals 1 mg/L, the detected values can be written in the same unit as the filter documents, while staying labeled as the system's reported levels.
How a Certification Listing Presents Fluoride
On the NSF directory, the AORO-50 shows the listing format. It names "Fluoride Reduction" as one claim among several for a plumbed-in system with a daily production rate of 11 gallons per day, with its replacement module, S1448RS, on the same line. A directory line like this records that the claim exists for the named model and its module, while concentrations and percentages are the kind of detail a performance data sheet or test report prints.
What a Complete Fluoride Record Settles
A fluoride record that prints a measured inlet and outlet, the volume at which they were taken and the line they were judged against lets a buyer see how far fluoride fell, when in the filter's use, and against what standard of test. Two products documented that way can be compared field by field, with the models, replacement schedule and operating conditions written beside the fluoride figures.
FAQ
What do two test points in one fluoride report show?
They show the same unit measured at two volumes. In the Viomi B6W's report, fluoride fell from 8.906 to 0.240 mg/L with a new filter and from 8.869 to 0.525 mg/L after 7,300 liters, below the report's 1.0 mg/L line at both points.
Is the 1.5 mg/L line in a certification the same as the federal fluoride limit?
The 1.5 mg/L figure is the maximum product water allowed during an NSF/ANSI 58 fluoride challenge at about 8 mg/L. The EPA's maximum contaminant level for public water systems is 4.0 mg/L. One describes a filter test and the other a utility standard.
How many gallons is 7,300 liters?
About 1,928 US gallons, using NIST's conversion of 3.785412 liters per US gallon.
Why does the AquaTru column show no single outlet value?
Measured outlet values such as the Viomi B6W's 0.240 and 0.525 mg/L sit in their own row. The Classic sheet instead states its fluoride result as a reduction across the certification test, 91.8% minimum and 93.5% average, together with the 1.5 mg/L maximum permissible product water, and those are the fields to set beside another document.
Share:
How to Tell Whether One Filter Covers Both PFAS and Microplastics
Orlando Water Notices and Routine Filtration: What to Check