Rheem Water Softener Review: Does Matching Your Heater Matter?
This Rheem water softener review starts with the question most buyers bring to it: does matching your Rheem water heater matter? No. The softener and the heater are covered by separate warranties from separate companies, and the heater's warranty certificate does not mention softeners at all. Owning both adds no cover and removes none. On its own merits, the Rheem Preferred series is a solid, NSF-certified, efficiency-rated demand softener. The RHS32 shares its published capacity figures with the Whirlpool WHES33, and the larger RHS42 is competitive on capacity at a sensible salt dose.
Rheem softeners are not sold on Amazon, so this review also names the closest Amazon alternatives.
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The Rheem Preferred Series at a Glance
The figures below come from the RHS32, RHS42 and RHW42 owner's manuals, and the flow ratings broadly match NSF's NSF/ANSI 44 listing for Rheem softeners, which also certifies all three for barium and radium reduction.
| Model | Resin | Rated flow | Max hardness | Clear-water iron | Best efficiency | Extra |
|---|---|---|---|---|---|---|
| RHS32 (Preferred) | 0.88 cu ft | 7.9 gpm | 105 gpg | 8 ppm | 4,940 grains/lb at 2.6 lb | None |
| RHS42 (Preferred Plus) | 1.20 cu ft | 9.9 gpm | 140 gpg | 11 ppm | 5,010 grains/lb at 2.5 lb | None |
| RHW42 | 1.20 cu ft | 9.9 gpm | 140 gpg | 11 ppm | 5,010 grains/lb at 2.5 lb | Wi-Fi |
A smaller RHS18 also appears on NSF's listing. All of them use demand regeneration with a variable salt dose: the controller picks the dose at regeneration time based on what it needs.
Where to buy. Rheem softeners are sold through Home Depot, not Amazon. The Wi-Fi model costs more than the RHS32. Check the current Home Depot price before you compare.
How this review was put together. No softener or heater was physically tested. The review uses the Rheem RHS32, RHS42 and RHW42 owner's manuals, a Rheem residential water heater warranty certificate, NSF's certification listings and the published capacity tables for each rival. Amazon listings for the alternatives were opened to confirm the pages exist.
Prices are not listed here because they change often. Use the buttons to see the current price on Amazon.
Does a Rheem Softener Change a Rheem Water Heater Warranty?
It does not, and the documents show why.
The softener's warrantor is not Rheem's heater business. Every Rheem softener manual names the warrantor as Water Channel Partners, of Eagan, Minnesota. Its terms are a one-year full warranty on parts and labour, three years on the electronic control board, and ten years on the salt tank and resin tank against rust, corrosion, leaks and bursting.
The heater's warrantor is Rheem Manufacturing's Water Heater Division. The Rheem residential water heater warranty certificate we read says it is "the only Warranty for this unit given by the Water Heater Division of Rheem Manufacturing Company". Its exclusions cover installation faults, dry firing, excess pressure and temperature, and a few that matter here:
- failures caused by operating the heater with the anode rod removed
- failures from any attachment, including any energy saving device, not authorized by Rheem
- tank failures when the heater is not supplied with potable water that is free to circulate
Nothing in it mentions water softeners, softened water, hardness or scale, either as a benefit or as an exclusion. A softener on the cold supply is not an attachment to the heater, and softened water is potable. There is also no clause that treats a Rheem-badged softener differently from any other brand.
What pairing does change has nothing to do with the badge. Any softener stops new scale forming in the tank. Any softener also makes the water more conductive, so the anode rod is used up faster. That matters for the warranty indirectly: a heater run with the anode gone is no longer protected, and running it with the rod removed is an exclusion. The detail, including how often to check the rod, is in water softener and storage water heater. The softener also has to sit before the heater on the cold line, as explained in water softener before or after water heater.
So buy the heater and the softener separately, each on its own merits.
Rheem Water Softener Review on Its Own Merits
Capacity ratings only mean something at a stated salt dose, a point covered in advertised vs usable softener capacity. Rheem's manuals give three points on each model's curve, so the softener can be compared with rivals at the dose you will actually run.
| Salt per regeneration | Rheem RHS32 | Rheem RHS42 | Whirlpool WHES33 | WaterBoss 900 |
|---|---|---|---|---|
| Minimum dose | 13,000 at 2.6 lb | 12,400 at 2.5 lb | 13,000 at 2.6 lb | 5,510 at 1 lb |
| Middle dose | 27,600 at 8.3 lb | 29,900 at 8.0 lb | 27,600 at 8.3 lb | 29,842 at 8.5 lb |
| Maximum dose | 33,000 at 14.1 lb | 42,400 at 16.3 lb | 33,000 at 14.1 lb | 36,490 at 15 lb |
| Rated grains per lb | 4,940 | 5,010 | 4,950 | 5,510 |
Three findings:
- The RHS32 and the Whirlpool WHES33 publish the same capacity at all three doses. Their efficiency ratings differ by 10 grains per pound, and NSF lists both under the same company. Treat them as one design with two badges. The WHES33's Amazon listing showed "currently unavailable" on 1 October 2026, so on Amazon the comparison is now academic.
- The RHS42's "42,000 grains" needs 16.3 lb of salt. At a normal 8 lb dose it delivers about 29,900 grains, level with the WaterBoss 900. Its real advantages are elsewhere: 1.2 cubic feet of resin, 9.9 gpm of rated flow and a 140 gpg hardness limit.
- On rated efficiency, the WaterBoss 900 leads, at 5,510 grains per pound at a 1 lb dose. That figure comes from a very small dose, so it regenerates often to achieve it.
Warranty against rivals. Rheem's one year of parts and labour, extendable to five with its RHWSC cleaner, matches Whirlpool's structure for its standard softeners. WaterBoss's owner's manual gives three years on mechanical and electronic parts and ten on the tank, valve body and brine cabinet, but it does not cover labour or the resin. Morton's standard models give one year on non-tank parts. If you will not buy cleaner three times a year, Rheem's real parts cover is one year.
The cleaner condition is strict. The manual asks for one bottle of RHWSC every four months from delivery, with proof of purchase kept, and says any other softener additive will not earn the extension.
Amazon Alternatives
Rheem sells no whole-house softeners on Amazon; only third-party adapters and cleaners turn up there. These are the closest equivalents that were in stock when checked on 1 October 2026:
EcoPure EPH130: the in-stock cabinet from Rheem's maker. This is not the RHS32's twin, and its specification is not published alongside the Rheem's. The listing describes a 2-in-1 cabinet that adds filtration media to the softening resin for better-tasting water, AutoSense demand regeneration with up to 40% less salt than traditional systems, and sizing for households of up to five people. The listing title gives no grain rating, so check the spec label against the table above before you choose it over an RHS32.
EcoPure EP42: the same size class as the RHS42. Retailer listings give 42,000 grains, up to 110 gpg and 11 ppm of iron, and NSF rates it at 8.2 gpm. We could not confirm its grains-per-pound figure from a current manual.
GE GXSH35W: a different maker's cabinet in the RHS32's size class. Sold on Amazon and at GE. It is not a Rheem twin: GE Appliances is the warrantor, not Water Channel Partners, and its 2025 models are certified to NSF/ANSI 44 by IAPMO R&T. Its owner's manual gives 1 cubic foot of resin, 13,311 grains at 2.6 lb, 32,636 grains at 9.8 lb and 37,065 at 17.1 lb, with 5,120 grains per pound at its minimum dose and up to 165 gpg of hardness. It adds built-in Wi-Fi alerts, but its clear-water iron rating is only 3 to 5 ppm (GE's specification page and manual differ), well below the RHS32's 8 ppm, and GE's full warranty is one year.
Not included: the Whirlpool WHES40E, often suggested as a Rheem alternative. Whirlpool's current softener brochure no longer lists it, Lowe's no longer sells it, and several of its parts are marked no longer available. The WHES33 and the WaterBoss 900, compared in the table above, both showed "currently unavailable" on Amazon on 1 October 2026; the WaterBoss 900 is still sold at Home Depot.
Who Should Not Buy a Rheem Softener
- Anyone buying it to protect a Rheem heater warranty. It does not. Any well-sized softener protects the heater equally, and the anode check is the same.
- Buyers who will not use the brand cleaner. Without it, parts and labour cover ends after one year.
- Wells with red water, iron bacteria or iron above the rating. The 8 and 11 ppm figures apply to clear-water iron only, and Wisconsin requires extra treatment above 5 ppm.
- Amazon-only shoppers. Rheem softeners are not sold there, and the like-for-like WHES33 was unavailable when checked; the EcoPure EP42 is the closest in-stock size match.
- Anyone wanting to avoid salt. That is a different technology with different trade-offs, covered in salt-based vs salt-free water treatment.
Buy a Rheem softener if its price at Home Depot beats the alternatives above, or if the RHS42's larger resin bed and higher flow suit your house. Do not buy one to match the heater.
Frequently Asked Questions
Does a Rheem water softener extend my Rheem water heater warranty?
No. The Rheem water heater warranty certificate is issued by Rheem Manufacturing's Water Heater Division and makes no mention of softeners or softened water. The Rheem softener's warranty names a different warrantor, Water Channel Partners of Eagan, Minnesota. Neither document gives extra cover for owning both, and neither takes cover away.
Who makes Rheem water softeners?
The Rheem Preferred softener manuals name Water Channel Partners of Eagan, Minnesota as the warrantor, and NSF's certification listing for the Rheem RHS18, RHS32, RHS42 and RHW42 names the same company. It also appears behind Whirlpool, Morton and EcoPure softeners on NSF's register, which is why several of these models share near-identical specifications.
Can I buy a Rheem water softener on Amazon?
No. Rheem Preferred whole-house softeners are not sold on Amazon; only third-party parts such as power adapters and cleaners appear there. Rheem softeners are sold through Home Depot. The Whirlpool WHES33, the closest match to the Rheem RHS32, showed as currently unavailable on Amazon on 1 October 2026. The in-stock Amazon options are the EcoPure EP42 and EPH130, from the same maker, and the GE GXSH35W, a cabinet softener from a different maker.
What is the warranty on a Rheem water softener?
The RHS32, RHS42 and RHW42 manuals give a one-year full warranty on parts and labour, three years on the electronic control board, and ten years on the salt storage tank and resin tank. The one-year parts and labour period can be extended to five years if you use one bottle of Rheem RHWSC softener cleaner every four months and keep the receipts.
Is softened water bad for a Rheem water heater?
No, but it changes the maintenance. Softened water stops scale building up in the tank, and it is more conductive, so the anode rod is used up faster. The Rheem heater warranty excludes failures caused by running the heater with the anode rod removed, so check the rod a year after the softener goes in and replace it when it is spent.
Which Rheem water softener should I buy?
Size it on your hardness, household and salt setting rather than the model name. The RHS32 suits smaller households at up to 105 gpg and 8 ppm of clear-water iron. The RHS42 and the Wi-Fi RHW42 have 1.2 cubic feet of resin, 9.9 gpm of rated flow and handle up to 140 gpg and 11 ppm of iron, which suits bigger homes and harder wells.
