# Rheem Preferred Platinum 42,000 Grain Smart Water Softener (RHW42) vs A.O. Smith 40,000 Grain Water Softener (AO-WH-SOFT-400T): specs and price compared

A sourced, side-by-side comparison of the Rheem Preferred Platinum 42,000 Grain Smart Water Softener (RHW42) (Rheem) and A.O. Smith 40,000 Grain Water Softener (AO-WH-SOFT-400T) (A.O. Smith) among water softeners. A.O. Smith 40,000 Grain Water Softener (AO-WH-SOFT-400T) is the cheaper of the two at $549.

## Side by side

| Spec | Rheem Preferred Platinum 42,000 Grain Smart Water Softener (RHW42) | A.O. Smith 40,000 Grain Water Softener (AO-WH-SOFT-400T) |
| --- | --- | --- |
| US price | $689 | $549 |
| Brand | Rheem | A.O. Smith |
| Grain capacity | 42.4 | 40 |
| System type | ion-exchange | ion-exchange |
| Flow rate gpm | 9.9 | — |
| Salt efficiency lbs per kgrains | — | — |
| Iron removal ppm | 11 | 10 |
| Nsf certifications | — | — |
| Smart app control | Yes | No |
| Tank warranty years | 10 | 10 |
| Msrp usd | 689 | 549 |

## Key differences

- Grain capacity: Rheem Preferred Platinum 42,000 Grain Smart Water Softener (RHW42) 42.4 vs A.O. Smith 40,000 Grain Water Softener (AO-WH-SOFT-400T) 40
- Iron removal ppm: Rheem Preferred Platinum 42,000 Grain Smart Water Softener (RHW42) 11 vs A.O. Smith 40,000 Grain Water Softener (AO-WH-SOFT-400T) 10
- Smart app control: Rheem Preferred Platinum 42,000 Grain Smart Water Softener (RHW42) Yes vs A.O. Smith 40,000 Grain Water Softener (AO-WH-SOFT-400T) No
- Msrp usd: Rheem Preferred Platinum 42,000 Grain Smart Water Softener (RHW42) 689 vs A.O. Smith 40,000 Grain Water Softener (AO-WH-SOFT-400T) 549

## Sources

- Rheem Preferred Platinum 42,000 Grain Smart Water Softener (RHW42): https://www.rheemwatertreatment.com/product/preferred-platinum/ (rheemwatertreatment.com, verified 2026-06-26)
- A.O. Smith 40,000 Grain Water Softener (AO-WH-SOFT-400T): https://www.aosmithatlowes.com/products/water-softeners/ao-wh-soft-400t/ (aosmithatlowes.com, verified 2026-06-26)

Canonical: https://frontdeskreview.com/gear/water-softeners/rheem-rhw42-vs-ao-smith-ao-wh-soft-400t/
Cite: Per The Front Desk Review, Rheem Preferred Platinum 42,000 Grain Smart Water Softener (RHW42) ($689) vs A.O. Smith 40,000 Grain Water Softener (AO-WH-SOFT-400T) ($549) — sourced spec-by-spec comparison at https://frontdeskreview.com/gear/water-softeners/rheem-rhw42-vs-ao-smith-ao-wh-soft-400t/
License: CC BY 4.0.