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How this review was put together: from NSF International’s public certification listing, Whirlpool’s performance data sheet and the WHER25 owner’s manual (links in “Sources” at the end). We have not tested this system ourselves. How we review. Last checked 28 October 2026.
The short version
The Whirlpool WHER25 is a simple three-cartridge under-sink reverse osmosis (RO) system with a storage tank: a combined sediment/carbon pre-filter, an RO membrane and a carbon post-filter, all in twist-in “UltraEase” cartridges under a cover. A light in the faucet base flashes amber when six months are up.
Its strongest point is the paperwork. NSF International lists the WHER25 under NSF/ANSI 58 with certified claims for lead, fluoride, arsenic (pentavalent), barium, cadmium, both forms of chromium, copper, cysts, nitrate/nitrite, radium, selenium, TDS and turbidity, plus NSF/ANSI 42 for chlorine taste and odor. Its weak points are a low daily output (NSF lists 14.76 gallons per day), a lot of water to the drain, and twice-yearly filter changes.
See the Whirlpool WHER25 on Amazon (paid link)
Who it suits, and who should look elsewhere
A good fit if you
- Want a certified claim for lead, fluoride, arsenic (V) or nitrate from a certifier you can look up yourself.
- Drink and cook with a modest amount of RO water (one to three people is a sensible guide at about 15 gallons a day).
- Want filter changes that need no tools and no housing wrench.
- Prefer a widely sold brand whose replacement cartridges are easy to find in stores.
Probably not the right pick if you
- Have water harder than 10 grains per gallon, or any iron, manganese or hydrogen sulfide, without treatment ahead of it. Those are the manual’s feed-water limits.
- Need a lot of RO water, or want to run a fridge and ice maker off it as well.
- Care about water waste. Its efficiency rating is about 11%, so roughly eight gallons go to the drain for every gallon of drinking water under typical use.
- Are on chloraminated city water and rely on the arsenic claim (see below).
Key specifications
From the WHER25 owner’s manual and performance data sheet, with NSF’s certified production figure.
| Spec | WHER25 | What it means in practice |
|---|---|---|
| Type | Under-sink RO with storage tank, no pump | Runs on house pressure. A battery powers only the faucet’s reminder light. |
| Cartridges | Pre-filter (sediment + carbon) WHEERF, RO membrane WHEERM, carbon post-filter (WHEERF set) | The pre- and post-filter come as a pair. |
| Certified daily production | 14.76 gallons per day (NSF listing; tested at 50 psi, 77°F, 750 ppm TDS) | Low compared with “75 GPD” systems, though those figures are often membrane ratings, not certified output. An older data sheet lists 18.46 gpd. |
| Efficiency rating | 10.6% (manual); 12.22% on the older data sheet | Most of the water entering the system goes to the drain. |
| TDS reduction (test) | 90.6% average, 86.5% minimum | A solid result for a basic RO system. |
| Feed pressure | 40–100 psi | The nitrate/nitrite claim only applies at 40 psi or more. |
| Feed water temperature | 40–100°F | |
| Max feed TDS | 2,000 mg/L | |
| Max hardness | 10 gpg at pH 6.9 | Soften first if you are above it. |
| Iron, manganese, hydrogen sulfide | 0 mg/L | Well water with any of these needs treatment first. |
| Feed pH | 4–10 | Membrane life is shorter at high pH (see maintenance). |
| Warranty | 1-year limited (owner’s manual) | Cartridges are not covered. |
Certification: what was verified
Status: Certified. NSF International’s listing for “Whirlpool WHER25” (listed company: Water Channel Partners) shows:
- NSF/ANSI 58 (reverse osmosis), daily production rate 14.76 gpd, with reduction claims for arsenic (pentavalent), barium, cadmium, hexavalent and trivalent chromium, copper, cysts, fluoride, lead, nitrate/nitrite, radium 226/228, selenium, TDS and turbidity. Replacement modules WHEERF and WHEERM.
- NSF/ANSI 42 for chlorine reduction and taste and odor reduction, with a 3,850-gallon rated service cycle for the WHEERF filter.
- It is also listed to CSA B483.1 and meets NSF/ANSI 372 for lead content.
NSF listing for the WHER25 (checked 28 Oct 2026).
What that does and doesn’t tell you:
- It does confirm a broad set of health-related claims for the complete system, tested by NSF.
- Arsenic comes with conditions. The claim is for pentavalent arsenic only, and the manual says to rely on it only on water with a detectable free chlorine residual. Chloramine isn’t enough to convert arsenic to the form RO removes well.
- No PFAS claim. The WHER25 isn’t certified for PFOA/PFOS. RO in general reduces PFAS well according to the EPA, but if PFAS is your main concern, a system with a certified PFOA/PFOS claim, such as the AquaTru Under Sink, is the safer buy.
- Not for water that is microbiologically unsafe or of unknown quality. The cyst claim means it can be used on disinfected water that may contain cysts.
What we like and what to weigh up
Strengths
- A broad NSF-listed claim set for the complete system, including cysts, fluoride and lead.
- Tool-free cartridges that twist out under a cover, with no housings to unscrew or O-rings to grease.
- A built-in reminder: the faucet light flashes amber at six months.
- A nitrate/nitrite test kit is supplied, so you can check that claim at home.
- Easy to find replacement parts in big-box stores as well as online.
Drawbacks
- Low output. About 15 gallons a day in certification testing, and less on cold winter water or low pressure.
- High water waste for every gallon produced, as the efficiency rating shows.
- Frequent filter changes: the manual says every six months for the pre- and post-filter.
- Strict feed limits: 10 gpg hardness and zero iron, manganese or sulfide.
- No remineralisation stage. The water will taste like plain RO water, which some people find flat.
Maintenance and running costs
From the WHER25 owner’s manual:
| Part | Replace | Note |
|---|---|---|
| Pre-filter and post-filter (WHEERF) | At least every 6 months, sooner if output slows | Change the faucet battery at the same time. |
| RO membrane (WHEERM) | When output or taste drops | The manual says “well over one year” at feed pH 6.8–7.7, and as little as 6 months at pH 8.5–10. |
| Whole system | Sanitize yearly | Whirlpool recommends its reusable sanitizing kit (sold separately). |
What drives the cost: two WHEERF sets a year, plus a membrane every year or two depending on your water’s pH. Check the current price of a WHEERF pair and a WHEERM membrane and compare a three-year total with the alternatives below. Prices change often, so we don’t quote them here. A TDS meter is a cheap way to tell when the membrane is wearing out.
Alternatives worth comparing
- Want a certified PFOA/PFOS claim as well? The AquaTru Under Sink is certified by IAPMO R&T (not NSF): lead and fluoride under NSF/ANSI 58 (file W-10194), VOCs and PFOA/PFOS under NSF/ANSI 53 (file W-10193), and microplastics under NSF/ANSI 401 (file W-10195), with the same 10 gpg hardness limit.
- Want a broad NSF-listed claim set with standard-size housings? See the iSpring RCC7AK-BLK.
- Want generic 10-inch filters? The APEC ROES-PH75 uses standard housings, though its WQA certification covers TDS only.
- Comparing them all: see our best under-sink reverse osmosis systems guide.
Common questions
Is the WHER25 the same as the Kenmore and EcoPure RO systems?
The WHER25 is made and warranted by Water Channel Partners, which also makes Kenmore- and EcoPure-branded water products. Similar-looking systems from those brands are separate models with their own listings, so check the NSF listing for the exact model you buy.
Can I use it on well water?
Only if the water is microbiologically safe and within the limits: no iron, manganese or hydrogen sulfide, and hardness of 10 gpg or less. The arsenic claim also needs a free chlorine residual. Get the well tested first.
Will it remove the sodium from softened water?
Yes, reducing dissolved solids such as sodium is what RO does, and running it after a softener also solves the hardness limit. See how to remove sodium from softened water.
Check current availability of the Whirlpool WHER25 on Amazon (paid link)