Aquasana SimplySoft 40K
A certified, salt efficient cabinet softener for a family of up to five on city water. Pick it over cheaper uncertified units if you want verified salt savings.
Amazon $749$749
The Aquasana SimplySoft 40K is the better water softener overall, rated 3.5 to 2.8. The Aquasana SimplySoft 40K leads on flow, warranty and value. The Aquasana SimplySoft 40K costs $73.77 less ($749 vs $822.77).
Kenmore 420
A certified 40,000 grain demand softener for well or city water, but the price is hard to justify against similar models.
Amazon $822.77$822.77
Prices were last checked November 1, 2026 and are subject to change; the price and availability shown by the retailer at the time of purchase apply.
Which should you buy?
- Choose the Aquasana SimplySoft 40K for flow (11 gpm service flow vs 7.7 gpm service flow), warranty (5 years on the valve, 10 years on the tanks vs 3 years on the valve, 10 years on the tanks) and value ($18.72 per 1,000 grains ($749, 40,000 grains) vs $20.57 per 1,000 grains ($822.77, 40,000 grains)).
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every 32,001 to 48,000 grains water softener; a clear win is highlighted. How we rank explains each one.
| Factor weight | Aquasana SimplySoft 40K | Kenmore 420 |
|---|---|---|
| Overall rating | 3.5/5 | 2.8/5 |
| Value 30% | 43 $18.72 per 1,000 grains ($749, 40,000 grains) | 34 $20.57 per 1,000 grains ($822.77, 40,000 grains) |
| Salt efficiency 20% | 71 4,423 grains per lb of salt | 50 salt efficiency not published (neutral score used) |
| Flow 15% | 50 11 gpm service flow | 0 7.7 gpm service flow |
| Warranty 25% | 44 5 years on the valve, 10 years on the tanks | 22 3 years on the valve, 10 years on the tanks |
| Certification 10% | 100 certified to NSF/ANSI 44 | 100 certified to NSF/ANSI 44 |
Specifications
| Aquasana SimplySoft 40K | Kenmore 420 | |
|---|---|---|
| Capacity | ||
| Rated capacity | 40,000 grains | 40,000 grains |
| Resin | 1 cu ft | - |
| Service flow | 11 gpm | 7.7 gpm |
| Salt efficiency | 4,423 grains per lb | - |
| Highest hardness | 200 gpg | - |
| Highest iron | 1 ppm | - |
| Control | ||
| Valve | - | Kenmore demand valve |
| Regenerates on demand | Yes | Yes |
| App or remote monitoring | No | No |
| Bypass valve included | Yes | - |
| Resin tank | 10 x 35 in | - |
| Certification and warranty | ||
| NSF/ANSI 44 | Yes | Yes |
| Valve warranty | 5 years | 3 years |
| Tank warranty | 10 years | 10 years |