Rheem Preferred Plus RHS42
A well rounded certified softener for a family of up to six on hard city or well water.
Home Depot $549$549
The Rheem Preferred Plus RHS42 is the better water softener overall, rated 3.7 to 3.4. The Rheem Preferred Plus RHS42 leads on flow and value. The Rheem Preferred Plus RHS42 costs $30.99 less ($549 vs $579.99).
Whirlpool WHES40
A good value 40,000 grain softener for a family of three to five, with certified salt efficiency and strong iron handling.
Blain's Farm & Fleet $579.99$579.99
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 Rheem Preferred Plus RHS42 for flow (9.9 gpm service flow vs 7.6 gpm service flow) and value ($13.07 per 1,000 grains ($549, 42,000 grains) vs $14.50 per 1,000 grains ($579.99, 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 | Rheem Preferred Plus RHS42 | Whirlpool WHES40 |
|---|---|---|
| Overall rating | 3.7/5 | 3.4/5 |
| Value 30% | 76 $13.07 per 1,000 grains ($549, 42,000 grains) | 66 $14.50 per 1,000 grains ($579.99, 40,000 grains) |
| Salt efficiency 20% | 100 5,010 grains per lb of salt | 100 5,094 grains per lb of salt |
| Flow 15% | 32 9.9 gpm service flow | 0 7.6 gpm service flow |
| Warranty 25% | 22 3 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
| Rheem Preferred Plus RHS42 | Whirlpool WHES40 | |
|---|---|---|
| Capacity | ||
| Rated capacity | 42,000 grains | 40,000 grains |
| Resin | 1.2 cu ft | 1.1 cu ft |
| Service flow | 9.9 gpm | 7.6 gpm |
| Salt efficiency | 5,010 grains per lb | 5,094 grains per lb |
| Highest hardness | 140 gpg | 125 gpg |
| Highest iron | 11 ppm | 10 ppm |
| Control | ||
| Valve | Rheem demand valve | Whirlpool demand valve |
| Regenerates on demand | Yes | Yes |
| App or remote monitoring | No | No |
| Bypass valve included | Yes | - |
| Certification and warranty | ||
| NSF/ANSI 44 | Yes | Yes |
| Valve warranty | 3 years | 3 years |
| Tank warranty | 10 years | 10 years |