Which RO Brands Document What Their Systems Remove, and What the Documents Show

Clear reverse osmosis (RO) documentation names each contaminant beside a measured result. The Viomi M1 fits a kitchen that wants that kind of record, since independent SGS testing reports its lead reduction at more than 99.87%. Other RO brands also put what their systems remove in writing, through performance data sheets, certification listings and product-page contaminant lists.

Independent Lab Results: Viomi M1 Tested by SGS

Alongside the lead figure, SGS puts the Viomi M1's PFOS reduction at more than 99.67% and its PFOA reduction at more than 99.42%. SGS has also granted the M1 its "SGS Performance Tester" mark for PFOS and PFOA reduction, and the challenge testing for those two refers to NSF/ANSI 58-2023, the standard whose challenge-and-limit format the data sheets also use. The full set of M1 documents is laid out in our guide to third-party filter documents by model.

At the tap, the M1's touchscreen faucet shows live TDS and the remaining life of the PCB and RO filters.

SGS results can also share a document with a certification, as on Waterdrop's G5 series data sheet, which keeps the two kinds of evidence in separate blocks. The first is the IAPMO R&T certification under NSF/ANSI 58, which covers TDS. The second sits under the line "Product also tested by SGS for contaminant below." and gives the influent concentration, product water concentration and reduction rate for lead, fluoride, nitrate, PFOS and PFOA, plus a microbial reduction test for total coliforms, ending with "Testing performed by SGS for the contaminants listed above." That block shows what a percentage means in the glass: lead went from 0.1558 mg/L in the test water to under 0.0002 mg/L in the product water, against a reference requirement of 0.005 mg/L, or 5 parts per billion, or less.

Product-Page Contaminant Lists: What Each System Targets

A product page lists the contaminants a brand names for a system, and test figures can sit right beside the names. The Viomi M1's list gives SGS percentages for lead, PFOS and PFOA and also names chlorine and microplastics, while the Viomi V8 PRO targets PFAS (PFOS and PFOA), lead, copper, arsenic, nitrate and fluoride.

Other brands' pages differ in what they attach to the list. iSpring's RCC7 page puts percentages on it, with lead at up to 98% and TDS at 80% to 90% or better, while the Waterdrop G3P800 page uses an asterisk to mark some items as "Tested by a third-party laboratory," which lets a reader see which entries have a lab result behind them. APEC takes a third approach on the ROES-50 page, listing about 55 substances under "Guaranteed to Remove the Followings," from aluminum to zinc.

Material Certification: NSF/ANSI/CAN 372 for Water-Contact Parts

NSF/ANSI/CAN 372 covers the lead content of the parts that carry drinking water. Intertek has issued Authorizations to Mark for NSF/ANSI/CAN 372:2024 covering the Viomi M1, Viomi V8 PRO and Viomi V6 PRO. Waterdrop's G5 series and AquaTru's models carry 372 through IAPMO R&T. The standard's background is covered in our guide to NSF/ANSI 372 certification.

Performance Data Sheets: What Each Brand's Sheet Lists

Data sheets are laid out as tables grouped by standard, and the columns differ from brand to brand.

The AquaTru, Culligan, Aquasana and Waterdrop sheets each put the standard's challenge or limit beside a test result, and what sits next to it tells a reader how the result was judged. A minimum and an average reduction, on the AquaTru and Culligan sheets, give the lowest and the overall result; a pass mark, on Aquasana's sheet for the SmartFlow (AQ-SFRO2), records that the claim met the permitted limit; and a reduction requirement column, on the Waterdrop G3P800 and G3P600 sheets, shows the target the result had to reach.

For lead, AquaTru's NSF/ANSI 58 table shows 97.5% minimum and 99.1% average, and Aquasana's sheet shows 99.8% at pH 6.5 and 99% at pH 8.5. PFAS shows up on three of the sheets: AquaTru gives PFOA and PFOS a table of their own under NSF/ANSI 53, Aquasana reports them together at 99.7% against a 0.02 µg/L limit, or 20 parts per trillion, and the G3P800 sheet adds a Total PFAS row at more than 99%. AquaTru also has a microplastics table under NSF/ANSI 401, where particles of 0.5 to under 1 micron show a 96.48% reduction.

The APEC ROES-50 and Kinetico K5 owner's manuals both set out TDS test conditions, with a 750±40 mg/L influent challenge and a 187 mg/L maximum in the product water. APEC presents these in a data-sheet box under NSF/ANSI 58 and adds a 75% minimum reduction requirement, while the Kinetico manual refers to the K5 performance data sheet for specific reductions. In plain terms, a 187 mg/L ceiling on a 750 mg/L challenge means about three quarters of the dissolved solids have to come out, the same share that the 75% minimum reduction requirement states.

Several of these sheets, including Aquasana's, APEC's and Culligan's, carry the same statement: the concentration of each listed substance entering the system "was reduced to a concentration less than or equal to the permissible limit for water leaving the system." In household terms, each substance on those sheets came out at or below the limit the standard sets for treated water.

Certification Database Listings: The Claims a Certifier Has on File

The NSF, IAPMO R&T and Water Quality Association databases list each certified model with its replacement parts, its daily production rate and the reduction claims on file, without percentages, so an entry shows which claims a certifier holds while the percentages stay on the data sheet. Because each database belongs to one certifier, a model's entry also shows which body certified it and under which standard. Entries can differ even within one brand. NSF lists the iSpring RCC7 under NSF/ANSI 58 for TDS reduction, while its RCC7-BLK and RCC7-BN variants carry nine claims including lead and fluoride, and the Water Quality Association lists the APEC ROES-50 for TDS and the APEC RO-Hi for a dozen claims. A brand's own statement and the database entry can also line up, as with the Kinetico K5: its page states that the system is certified by WQA to NSF/ANSI 58 for PFOS and PFOA reduction, and WQA's entry lists lead along with PFOA and PFOS.

IAPMO R&T certificates add a note on who ran the tests: listed products "have been tested by an IAPMO R&T recognized laboratory," recognized for compliance with ISO/IEC 17025. The Water Quality Association adds that its certification reviews a product's literature as well as its performance and materials.

What the Documents Show Side by Side

Lead, PFOS and PFOA results appear as individual contaminant rows in lab results and data sheets, each with the influent level or the standard's requirement next to the result. A TDS reduction result shows how far dissolved solids drop as a group under test conditions, while a 372 certificate covers the lead content of the parts that touch the water.

FAQ

How are removal rates measured?

NSF/ANSI 58 is the standard for reverse osmosis systems, which NSF describes as using reverse pressure to force water through a semi-permeable membrane. NSF adds that, with no federal regulations for residential filters and RO systems, these voluntary national standards "establish minimum requirements for the safety and performance of these products in treating water." In certification testing, the system is fed water spiked to a set challenge concentration, and the water leaving the system is measured against the standard's requirement, either a maximum concentration in the product water or a minimum percent reduction. Data sheets state this directly: the concentration of each substance entering the system "was reduced to a concentration less than or equal to the permissible limit for water leaving the system." Waterdrop's G5 SGS block lists the influent concentration, product water concentration and reduction rate for the items SGS tested.

How is a product-page list different from a certification listing?

A product-page list names what a system is designed to target, and a certification listing names the claims a certifier has on file for a specific model under a specific standard. NSF notes that "Manufacturers choose which contaminants their product will reduce," which is why the two lists can differ in length, and that the numbers in standard names "are not a ranking or rating system."

Do test results for an older model still apply to a newer one?

Each document names the models it covers. AquaTru's Under Sink page now links a data sheet for model ATU200, which carries its own PFOA and PFOS rows, and the AquaTru Classic sheet names its six AT2000-series models one by one. Certification listings work the same way: IAPMO R&T lists the AquaTru AT2000 and its AT2002 replacement element as one entry, and NSF lists the iSpring RCC7 separately from its RCC7-BLK and RCC7-BN variants.

What does a TDS reduction figure tell you?

TDS measures all dissolved solids together, so a TDS reduction result shows how much the dissolved solids dropped as a group under test conditions. The EPA's WaterSense criteria for point-of-use RO systems treat "Total Dissolved Solids Reduction" as a baseline and list "Contaminant Reduction" for any additional contaminants a manufacturer claims as a separate item, which is why data sheets give individual rows for substances like lead and fluoride. The EPA's secondary standards list 500 mg/L for TDS as a guideline set for aesthetic considerations such as taste, and the NSF/ANSI 58 TDS test on several data sheets uses a 750 mg/L challenge with a 187 mg/L limit in the product water.