Quick Answer: The Kenmore 350 is a reasonable all-in-one cabinet softener for 1–4 people on city water with moderate hardness. It's rated 32,000 grains with a 7.2 gpm max flow, and it's simple to set up. Don't buy it for a well with iron or for very hard water. Get the Kenmore 420 instead, which is listed for up to 120 gpg hardness and 10 ppm clear-water iron. If you're just comparing cabinet softeners, the GE GXSH35W adds a little capacity plus WiFi leak and salt alerts.
Disclosure: As an Amazon Associate, Grains & Gallons earns from qualifying purchases.
If you grew up with a Kenmore softener humming in the basement, you're probably wondering whether the name still means the same thing now that Sears isn't the store it was. Short answer: Kenmore softeners are still sold, mostly online now. Current Amazon listings for the 350 and 420 show 2024 manufacture dates, and the 420 listing names Water Channel Partners as the manufacturer. The model numbers have stayed the same for over a decade. In 2011, Sears announced IntelliSoft2 versions of the 350 (model 42-38350) and 420 (42-38420), and those same numbers are on the boxes today.
So you're buying a long-running design, not a new one. That has upsides and downsides. Here's what the current listings and Kenmore's older documentation show. I haven't installed one myself, and I've marked where the published specs are vague.
In this guide
The two Kenmores you'll actually choose between
Kenmore's lineup has gone through several model numbers, but on Amazon right now it comes down to these two:
| Kenmore 350 | Kenmore 420 | |
|---|---|---|
| Rated capacity | 32,000 grains | 40,000 grains |
| Valve | 3/4" "High Flow" | 3/4" "Ultra Flow" |
| Max flow rate | 7.2 gpm | 7.7 gpm |
| Max hardness | Not stated on current listing | Up to 120 gpg |
| Clear-water iron | "Helps reduce" (no ppm given) | Up to 10 ppm |
| Resin | Not stated | 1.11 cu ft |
| Size / weight | 20.5" x 15" x 48", 80 lb | 20.5" x 15" x 48", 102 lb |
| Household (per listing) | 1–4 people | Marketed for larger households |
| Warranty | 1 yr full · 3 yr electronics · 10 yr tank | Same |
| Certification | Listed "NSF certified" (standard not named) | Same |
Both use Kenmore's IntelliSoft control, which learns your water-use pattern and regenerates only when needed. Both have a digital display showing flow and salt level, a built-in sediment screen, and come with a bypass valve and install kit.
How far 32,000 grains goes
32,000 is a maximum-salt rating, and cabinet softeners almost always rate their peak capacity at a high, less efficient salt dose. A rough check for a family of three on 12 gpg water, at about 75 gallons per person per day:
- 3 × 75 × 12 = 2,700 grains a day
- Divide 32,000 by 2,700 and you get about 12 days at full capacity. The control keeps a reserve, so it'll regenerate sooner.
That's comfortable. Now try a family of five on 20 gpg: 5 × 75 × 20 = 7,500 grains a day, which means a regeneration every three or four days at full salt. The 350 can do that, but you'll burn through salt, and that's the household Kenmore's own listing steers toward the 420. Our softener sizing guide has the full method if you want to plug in your own numbers.
The current 350 listing doesn't publish a maximum hardness. Sears' 2011 announcement of the then-new 350 described it as suited to families of up to six and hardness up to 45 grains per gallon. Treat that as background, not a current spec, and ask the seller if your water is anywhere near that.
What I'd want to know before buying, and what the listings leave out
Certification details. "NSF certified" without a standard number isn't enough. Softener performance falls under NSF/ANSI 44. An older Kenmore owner's manual I read (for models 38306/39306) did state NSF/ANSI 44 certification, but that's an older model. Check the current one in NSF's listings yourself. Here's how to verify a softener certification in a couple of minutes.
Odd listing data. The 350 listing shows a "maximum TDS 250 ppm," the 420 listing shows "10 ppm," and both say "no power source required" next to a digital display. These look like data-entry errors, not engineering limits, but they make it harder to trust the details.
Warranty length. One year full (parts and labor), three years on electronics, ten years on the tank. That's typical for a big-box cabinet softener and well short of the lifetime valve coverage some online brands advertise. The 420 listing also mentions "up to 5 years of full coverage," which doesn't match its own warranty line. Get the terms in writing.
What owners report
I read through a set of owner reviews on a retailer listing for the 350 and 420. The positives were consistent: install is straightforward, regeneration is quiet, and one reviewer measured roughly 30 gallons of water per regeneration. The negatives clustered around one thing: control board failures around the one-year mark, reported by more than one owner of each model. One 420 owner also reported brown water after install, which usually means iron or sediment being stirred up and is worth a call to the seller.
That pattern is why the 3-year electronics warranty matters. Register the unit, keep the receipt, and if the display goes blank, start with our error code and blank display guide before you file a claim.
Check price on Amazon: Kenmore 350
What installing it involves
The box includes the softener, a bypass valve and an install kit. The plumbing side is a 3/4" valve, so on a 3/4" main line it's a straightforward loop. On a 1" main, the 3/4" valve becomes the bottleneck. With a 7.2 gpm max flow, that matters more in a big house than a small one. You'll also need:
- A drain within reach of the drain hose, such as a floor drain, laundry standpipe or utility sink, with an air gap where your code calls for one.
- A standard outlet for the control.
- A spot that stays between 40°F and 120°F with water pressure between 20 and 125 psi, per the listing's operating range. That rules out an unheated garage in cold climates.
- Room for an 80 lb cabinet about 20.5" x 15" footprint and 48" tall, plus space above to lift the lid and pour in salt.
After it's running, set your measured hardness (not a guess) in the control, and let the first regeneration finish before you judge the results.
When the 420 is worth the extra size
Go with the Kenmore 420 if any of these apply:
- You're on a well with some clear-water (ferrous) iron. The 420 lists up to 10 ppm. Ferric (already rusty) iron and iron bacteria are a different problem, and you can read more in can a water softener remove iron?
- Your hardness is in the 20s or higher.
- There are four or more of you, or you have two showers running at once most mornings.
Keep in mind it's 22 lb heavier and has the same 3/4" valve, so the flow gain is modest (7.7 vs 7.2 gpm). (Check price on Amazon.)
Cabinet softeners to compare it against
GE GXSH35W Smart Softener (35,000 grain). It's in the same cabinet class, a little bigger than the 350, and its pitch is connectivity. Built-in WiFi sends continuous-flow and low-salt alerts to your phone through GE's SmartHQ app, and with GE's optional shutoff valve you can close the main remotely if it detects a leak. It has 1" connections with included quick connectors for 3/4" or 1-1/4" plumbing, plus a blending valve so you can dial in how soft the water is. The listing doesn't publish hardness or iron limits, so ask GE before you put it on a well. Check price on Amazon: GE GXSH35W
EcoPure EPS110. A smaller all-in-one cabinet (the resin tank sits inside the brine tank) for one or two people and one or two bathrooms, so it suits the smaller end of the Kenmore 350's range. EcoPure doesn't sell it by grain rating; it says its AutoSense demand regeneration matches a 32,000-grain system while using up to 40% less salt. The warranty matches Kenmore's: 1 year full, 3 years on electronics, 10 years on the tank. Check price on Amazon: EcoPure EPS110
If you're replacing an old Kenmore that's simply worn out, also think about whether you want a cabinet unit at all. Two-tank systems with Fleck or Clack valves are easier to repair down the road. Our how long does a water softener last guide covers what usually fails first.
Verdict
The Kenmore 350 is a simple choice for small to mid-size city-water households, and it's not a bad one. You get a compact cabinet, adaptive regeneration, and a 10-year tank warranty. What holds it back is a thin spec sheet, a short 1-year full warranty, and owner reports of first-year board failures. If your water is hard, iron-tinged or on a well, step up to the 420 or compare the GE GXSH35W line by line.