Quick Answer: Kenmore and Whirlpool softeners come from the same place. Both current manuals name Water Channel Partners of Woodbury, Minnesota, as the licensed manufacturer. So pick by model, not brand. The Whirlpool WHES40E handles harder water (rated to 125 gpg vs 90), more iron (10 ppm vs 8) and more capacity (40,000 vs about 32,000 grains), so it's the better buy for most families if you can find one. It isn't currently sold on Amazon; there, the closest step up from the 350 is Kenmore's own 40,000-grain Kenmore 420. The Kenmore 350 is enough for 1–4 people on moderately hard water, and it's slightly more salt-efficient at its lowest setting.
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I expected this comparison to be about two appliance giants with different engineering. It isn't. Pull up the owner's manuals and both name the same company. Whirlpool's WHES40 manual lists Water Channel Partners, 1890 Woodlane Drive, Woodbury, MN as the manufacturer. Kenmore's 350 manual says the Kenmore name is used under license by Water Channel Partners, Woodbury, MN.
Even the aftermarket hints at it: replacement bypass valve assemblies on Amazon are sold as fitting Kenmore, GE, Whirlpool, Morton and others in one listing.
So "which brand is better?" is the wrong question. The useful one is "which of these specific models fits my water and my household?" Every spec below comes from the current manuals and retail listings. Nothing here is from my own testing.
In this guide
Spec sheet, line by line
| Kenmore 350 | Whirlpool WHES40E | |
|---|---|---|
| Max capacity | 32,100 grains @ 13.3 lb salt | 40,000 grains @ 15.5 lb salt |
| Low-salt capacity | 12,600 grains @ 2.5 lb | 17,300 grains @ 3.4 lb |
| Rated efficiency | 5,040 grains/lb @ 2.5 lb | 5,094 grains/lb @ 3.4 lb |
| Rated service flow | 7.2 gpm | 7.6 gpm |
| Max hardness | 90 gpg | 125 gpg |
| Max clear-water iron | 8 ppm | 10 ppm |
| Regeneration | Demand-based (Kenmore "IntelliSoft") | Demand-initiated, variable salt dose |
| Salt storage | Not confirmed | 200 lb |
| Certifications | NSF/ANSI 44 and 372; WQA CSA B483.1 | NSF/ANSI 44 and 372; WQA CSA B483.1 |
| Warranty | 1 yr full; 3 yr electronics; 10 yr tank (per retail listing) | 1 yr full (5 yr with Whirlpool softener cleaner); 3 yr control board; 10 yr tanks |
| Price | Check price on Amazon | Not currently listed on Amazon |
Whirlpool figures are from Whirlpool's owner's manual for the WHES40 series. Kenmore figures are from the 625.383500 (Kenmore 350) owner's guide, with warranty terms from a retail listing.
The three numbers that actually separate them
Max hardness (90 vs 125 gpg). Most US homes are well under 90 gpg, so this only matters at the extremes. But if your well tests in the 30s or 40s and you also have some iron, you'll want headroom. The Whirlpool has more.
Iron (8 vs 10 ppm). Both are generous for cabinet softeners. In practice, running a softener anywhere near its iron limit means more frequent resin cleaning and earlier fouling. If you're above 2–3 ppm, plan on an iron filter regardless.
Capacity (32k vs 40k). Here's where household size comes in. A rough calculation:
- Family of 4, 15 gpg: 4 × 75 gal × 15 = about 4,500 grains/day. The Kenmore at max salt covers about 7 days; the Whirlpool covers about 9. At the efficient low-salt settings, the Kenmore regenerates every 2–3 days and the Whirlpool about every 4.
- Couple, 10 gpg: 2 × 75 × 10 = 1,500 grains/day. Either one coasts. The Kenmore at its lowest setting lasts about 8 days.
Frequent regeneration isn't a disaster, since demand-initiated units only regenerate when needed. But it does mean more water down the drain. For the larger family, the Whirlpool's extra capacity is the better fit. Here's what grain capacity actually means if you want the longer explanation.
Salt efficiency is basically a tie
At their lowest salt doses, both are rated just over 5,000 grains per pound (5,040 for Kenmore, 5,094 for Whirlpool). That's good for any softener. Whichever you buy, the bigger savings come from setting the salt dose correctly rather than leaving it at the factory default. See how to set the salt dose on a water softener, and get the hardness setting right while you're there with how to set hardness on a water softener.
A year of salt, roughly
Same family of four at 15 gpg (about 4,500 grains a day), run at each unit's most efficient setting:
- Kenmore 350 at 5,040 grains per pound: about 0.9 lb of salt a day, roughly 325 lb a year.
- Whirlpool WHES40E at 5,094 grains per pound: about 0.9 lb a day, roughly 320 lb a year.
That's close enough to call a tie, around eight 40-lb bags a year either way. The real difference is the Whirlpool's 200-lb salt bin, which lets you top it up less often. If lugging bags down basement stairs is the part you dread, that matters more than the efficiency figures.
On a private well
Well owners should pay the most attention to the iron and hardness limits. Well water often runs harder than city water and carries some iron, and both numbers can drift with the seasons. The Whirlpool's 125 gpg and 10 ppm ratings give more margin. Neither unit is a substitute for an iron filter if you're above a couple of ppm, or for testing your water before you buy.
How you'll know you bought too small
Undersizing is the most common regret with 30,000- to 40,000-grain cabinet units. Watch for these signs in the first few months:
- The display shows a regeneration every day or two even at a moderate salt setting.
- Hardness slips through late in the day or after laundry, then returns to soft after a regen.
- Salt use is noticeably higher than the yearly estimate above.
If you see that with the Kenmore 350, the fix is usually the bigger Whirlpool (or another 40k+ unit), not more salt. We list the other symptoms in signs a water softener is undersized. The reverse problem, a unit far too big for a small household, is less of an issue with these demand-initiated cabinets than with oversized tank systems, but it's still worth sizing honestly.
Warranty: read the Whirlpool condition
The two warranties are similar on paper: a year of full coverage, three on the electronics or control board, and ten on the tanks. Whirlpool adds a twist. Its manual extends the full warranty to five years if you use Whirlpool's WHE-WSC softener cleaner. That's worth doing if you're buying the Whirlpool. Keep the receipts, because it's a condition.
Install is the same job either way
Both need a drain, an outlet and a spot near the main line, and both plumb in through a bypass valve. Because they come from the same licensed maker, some replacement parts, like bypass assemblies, are sold as fitting both. Over the years, the bypass is one of the places that can start to weep; here's what to do if the bypass valve leaks.
Other models from the same shelf
- Kenmore 420: the 40,000-grain step up from the 350, sized for 1–5 people. It uses the same IntelliSoft demand regeneration, adds a sediment pre-filter and enhanced clear-water iron reduction aimed at well water, and carries the same 1-year full / 3-year electronics / 10-year tank warranty. It's the closest thing to the WHES40E you can order on Amazon right now. I didn't find its full manual spec sheet, so compare its hardness and iron limits before buying. Check price on Amazon
- EcoPure EPS110: an all-in-one cabinet sized for 1–2 people and 1–2 bathrooms, with demand regeneration and a built-in sediment shield. Pick it if even the Kenmore 350 is more softener than your household needs. Check price on Amazon
- GE Smart Water Softener 35,000 grain: a WiFi softener that sends low-salt reminders and continuous-flow alerts to your phone, and can shut off the house water remotely if you add GE's optional shutoff valve. Pick it if remote alerts matter to you. Check price on Amazon
- Kenmore Elite 520 Hybrid: a softener with a built-in, self-cleaning carbon media filter for chlorine taste and odor, plus a 1" high-flow valve. It's the option if you're on city water and want softening and taste improvement in one unit. Check price on Amazon
Which one to buy
For most families, the Whirlpool WHES40E. It has more capacity, more hardness and iron headroom, a bigger salt bin, and a path to a 5-year full warranty. If you can't find one in stock, the Kenmore 420 gives you the same 40,000-grain class under the Kenmore badge. Choose the Kenmore 350 if you're a small household on moderately hard water, or if it's the better deal the day you shop. Under the badge, it's the same licensed manufacturer.