Kenmore 420 Review
Verdict: A 40,000-grain cabinet softener listed for very hard water and clear-water iron, with a sediment pre-filter for well water. It ranks #1 in our best water softener for well water list.
Hands-on: used in our own household, recently installed, with long-term results to follow. Read our notes.
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| Grain capacity | 40,000 grains* |
|---|---|
| Max flow rate | 7.7 gpm* |
| Clear-water iron | 10 (clear-water)* |
| Max hardness | 120 gpg* |
| Warranty | 1 yr full, 3 yr electronics, 10 yr tank* |
* From the seller's Amazon listing; not yet confirmed by the manufacturer.
Certification claims are shown only once the manufacturer's documentation confirms them.
Unmarked values come from Kenmore's own pages or manuals; values marked * come from the Amazon listing (ASIN B00JH3XUNA). Model 420.
Check price on Amazon ($600–$900)Hands-on notes: the Kenmore 420 in our own household
First-hand use by the site owner, recently installed, with long-term results to follow. A home with an existing three-filter and UV treatment setup, re-plumbed to route water through the Kenmore. Self-installed; first water softener in this home. These are personal observations, not lab measurements.
Delivery
It arrived in good condition with the deluxe delivery service: the crew carried it down to the basement and took away the boxes and plastic afterwards, which saved a job.
Installation and the drain
With basic plumbing knowledge, installation was relatively easy. We re-did our existing three-filter and UV setup to route water through the Kenmore, and the plumbing took about 60 minutes. The installation video (via a QR code) was the main set of instructions, including adding water and salt and running the first regeneration.
Plan the drain before you start. To meet local plumbing code we installed a P-trap with an air gap and connected it to existing plumbing so regeneration water drains to the septic system. The supplied drain hose was much too short for our layout, so we had to buy more; a longer hose in the box would help.
Setup and operation
Initial setup was straightforward and the control panel is easy to use. The first regeneration took about 90 minutes. In normal operation the unit is silent; regeneration is louder, but not excessively.
What we noticed
The water feels noticeably different: showering and washing hands now has the slippery feel typical of softened water, which we didn't have before. Water from the refrigerator doesn't taste salty, which we were glad to confirm. We haven't measured hardness or iron before and after, so this is based on feel rather than a test.
Verdict so far
Happy so far. Installation was manageable, the controls are easy, and the difference in the water is noticeable. We'd recommend it to DIY homeowners with some plumbing experience: plan the drain connection to code and have extra drain hose ready before you start.
More on drinking water: see our softener and filtration picks; for setup, our installation guide covers programming hardness.
What we didn't measure: incoming and softened-water hardness; iron before and after; salt use; days between regenerations. Test your own water before and after with a hardness test kit to confirm a softener is working.
Who the Kenmore 420 is for
Private-well homes with hard water and moderate clear-water iron.
Who should skip it
Wells with red (oxidised) iron, iron bacteria or sulfur smell: you need an iron filter first.
Pros
- Listed for very high hardness and clear-water iron
- Sediment pre-filter built for wells
- Silent in normal use with easy controls, in our install
Cons
- Lower flow than the full-size two-tank systems
- 1-year full warranty
- Supplied drain hose was too short for our install; manual is QR-code only
Our take
Well water usually brings two problems a city softener isn't built for: sediment and dissolved iron. The 420's listing covers both, with a sediment pre-filter and a stated clear-water iron limit.
Clear-water (ferrous) iron is dissolved and can be exchanged by softener resin. Red, ferric iron is already particles; it fouls resin and needs filtration first.
How it compares on paper
- Against the Aquasana SimplySoft 40K: a lower rated flow (7.7* vs 11.02 gpm).
- Against the AFWFilters Fleck 5600SXT 48K: less capacity (40,000* vs 48,000* grains) and a lower rated flow (7.7* vs 14* gpm).
- Against the Aquasure Harmony 48K: less capacity (40,000* vs 48,000 grains) and a lower rated flow (7.7* vs 12* gpm).
* Seller-listed value, not yet confirmed by the maker; unmarked values are from the manufacturer.
Kenmore 420 sizing at a glance
Using the 40,000-grain capacity from the seller listing, here is roughly how many days it runs between regenerations. At 12 gpg, a family of four would regenerate the Kenmore 420 about every 8 days, and two people on 18 gpg water about every 11 days; aim for 5–8.
| Household | 8 gpg | 12 gpg | 18 gpg | 25 gpg |
|---|---|---|---|---|
| 2 people | 26 | 17 | 11 | 8 |
| 4 people | 13 | 8 | 5 | 4 |
| 6 people | 8 | 5 | 3 | 2 |
Spec score: 6.7/10 (provisional)
| Capacity | 1.9 / 3 — 40,000 grains (64,000 = full marks) |
|---|---|
| Flow | 1.5 / 3 — 7.7 gpm (15 gpm = full marks) |
| Iron handling | 1.5 / 1.5 — 10 ppm clear-water iron (10 ppm = full marks) |
| Value | 1.8 / 2.5 — price band $600-$900 |
Alternatives to the Kenmore 420
- EcoPure EP42 (#2): Highest stated iron limit.
- Aquasure Harmony 50K Fine Mesh (#3): Fine-mesh resin and pre-filter at a mid price.
- DuraWater Fleck 5600SXT Iron Blaster 48K (#4): Fleck valve with fine-mesh resin; no iron limit stated.
- PRO+AQUA 80K (#5): Big wells and big families; low iron limit.
See all our picks in the best water softener rankings, the top three on our best home water softener systems page, or every spec side by side in the water softener comparison table, or more from Kenmore. Not sure about size? Use the calculator in our water softener buying guide.
Before you buy: how a water softener works, what water softener installation involves, the full cost of running a softener and the maintenance it needs. On a private well? See our water softener for well water picks.