Whirlpool vs Rheem vs Morton vs A.O. Smith: Store-Brand Water Softeners Compared
Quick answer: The big-box softeners are closer than their brands suggest. NSF's listing puts the Whirlpool, Rheem, Morton, Kenmore and North Star models under the same company, Water Channel Partners of Eagan, Minnesota, and all the models below are NSF/ANSI 44 certified and efficiency rated. The real differences are capacity, iron limits and where they are sold. For most families on city water, the Morton M34 or Rheem RHS32 is plenty. If you have more iron or a larger home, look at the A.O. Smith 40,000 to 45,000 grain models, rated for up to 10 ppm ferrous iron.
Why Store Brands Are So Similar
Walk the plumbing aisle and you will see Whirlpool, Rheem, Morton and Kenmore softeners side by side. In NSF's official NSF/ANSI 44 listing, all of these, plus North Star, appear under one company: Water Channel Partners, Eagan, Minnesota (NSF listing). Rheem's own manual names Water Channel Partners as the manufacturer. A.O. Smith and GE are listed separately under their own names.
Every model compared here is listed for hardness reduction (NSF verified the published capacity ratings) and efficiency rated, which NSF defines as removing at least 3,350 grains of hardness per pound of salt while using 5 gallons of water or less per 1,000 grains removed. Several are also listed for barium and radium reduction. So the certification question is settled: these are legitimate, independently certified softeners. What differs is size and features.
Specs Compared
| Model | Capacity at Max Salt | Capacity at Min Salt | Efficiency at Min Salt | Max Hardness | Max Iron | Rated Flow |
|---|---|---|---|---|---|---|
| Whirlpool WHES33 | 33,000 grains | See manual | Efficiency rated (NSF) | 105 gpg* | 9 ppm* | 8 gpm (NSF) |
| Rheem RHS32 | 33,000 @ 14.1 lb | 13,000 @ 2.6 lb | 4,940 grains/lb | 105 gpg | 8 ppm clear-water | 7.9 gpm |
| Morton M34 | 34,900 @ 14.5 lb | 13,700 @ 2.7 lb | 5,060 grains/lb | 110 gpg | 9 ppm clear-water | 7.8 gpm |
| A.O. Smith AO-WH-SOFT-350C | 35,000 @ 15 lb | 5,210 @ 1 lb | 5,210 grains/lb | 90 gpg (compensated) | 10 ppm ferrous | 7.5 gpm |
| A.O. Smith AO-WH-SOFT-400T | 40,000 @ 13 lb | 6,510 @ 1.25 lb | 5,210 grains/lb | 100 gpg (compensated) | 10 ppm ferrous | 8 gpm |
| A.O. Smith AO-WH-SOFT-450T | 45,000 @ 18.75 lb | 6,510 @ 1.25 lb | 5,210 grains/lb | 100 gpg (compensated) | 10 ppm ferrous | 7.5 gpm |
From the owner's manuals for the Rheem RHS32, Morton M20 to M34 and A.O. Smith 350C/400T/450T, and NSF's NSF/ANSI 44 listing. *Whirlpool hardness and iron figures are from a retailer listing, not the manual, which we could not retrieve.
The Capacity Number on the Box
The grain number in a softener's name is its capacity at the highest salt setting. The Rheem "32,000 grain" RHS32 is rated at 33,000 grains using 14.1 lb of salt per regeneration, but only 13,000 grains at its most efficient 2.6 lb setting, where it reaches 4,940 grains per pound of salt. The Morton M34 shows the same pattern: 34,900 grains at 14.5 lb, 13,700 grains at 2.7 lb.
That matters for sizing. A softener that regenerates efficiently every few days will use less salt than one forced to run at maximum salt. The manuals add that rated efficiency is the best case measured in the lab; real-world efficiency is usually lower because of hardness, water use and other contaminants. To size yours, multiply your hardness in grains per gallon by your daily water use, then compare with the efficient capacity, not just the headline number. Our cost guide shows salt use by hardness, and our installation guide walks through a DIY install.
Water use is low on all of these: the Rheem uses 1.9 gallons per 1,000 grains at its minimum salt dose (33.3 gallons per regeneration at maximum), and the Morton M34 uses 2.3 gallons per 1,000 grains (31.6 gallons at maximum).
Whirlpool WHES33
The Whirlpool WHES33 is NSF/ANSI 44 listed for hardness reduction and efficiency, with an 8 gallon-per-minute flow in NSF's listing. Retailer specs give a 33,000-grain capacity, a maximum of 105 grains per gallon of hardness and up to 9 ppm of clear-water iron. It is a demand-initiated unit made by the same company as the Rheem and Morton models, so expect similar performance; choose it if the price, availability or warranty suits you best.
Rheem Preferred RHS32
The Rheem RHS32 is listed by NSF for hardness reduction, efficiency, and barium and radium 226/228 reduction. Its manual gives 13,000 to 33,000 grains depending on salt dose, a maximum of 105 gpg hardness and 8 ppm clear-water iron, a 7.9 gpm service flow, and water pressure limits of 20 to 125 psi. Rheem's manual notes that in California you must turn the Salt Efficiency feature on. Rheem markets it for households of up to four people.
Morton M34
The Morton M34 (System Saver line) has the highest hardness limit here at 110 gpg and up to 9 ppm clear-water iron, with WQA test data cited for the iron claim. Capacity runs from 13,700 grains at 2.7 lb of salt to 34,900 grains at 14.5 lb, with 5,060 grains per pound at the efficient setting, and a 7.8 gpm service flow. Morton's smaller M20, M27 and M30 models suit smaller households or softer water.
A.O. Smith AO-WH-SOFT Series
A.O. Smith's AO-WH-SOFT models come in 35,000 (350C), 40,000 (400T) and 45,000 (450T) grain sizes, all rated at 5,210 grains per pound at the minimum salt dose and up to 10 ppm of ferrous iron, the highest iron rating in this comparison. The manual lists a minimum pH of 7, water pressure of 20 to 80 psi, and a maximum chlorine figure of 0 ppm in its specifications table; if you are on chlorinated city water, ask A.O. Smith how that applies to your installation. NSF's listing includes the AO-WH-SOFT-350, 400T and 450T for hardness reduction, efficiency, and barium and radium reduction.
Iron: What These Softeners Can Handle
A.O. Smith's manual explains the types of iron clearly. Only ferrous (clear-water, dissolved) iron can be treated by a softener. Ferric iron is already particles that can foul the resin and should be filtered out first; organic or bacterial iron needs other treatment; and colloidal iron cannot be removed by a softener (A.O. Smith).
- Set compensated hardness: add 5 grains per gallon to your hardness setting for every 1 ppm of ferrous iron. Example: 20 gpg plus 3 ppm iron = 35 gpg setting.
- Clean the resin: A.O. Smith recommends a resin bed cleaner every six months if your water has ferrous iron.
- Check local rules: the Rheem and Morton manuals note that Wisconsin requires additional treatment if clear-water iron exceeds 5 ppm.
For higher iron, see our well water filtration guide.
Which One Should You Buy?
- City water, 1 to 4 people, moderate hardness: Morton M34, Rheem RHS32 or Whirlpool WHES33. They are close enough that price and warranty should decide.
- Very hard water: Morton M34, with the highest listed hardness limit (110 gpg).
- Well water with ferrous iron, or a larger household: A.O. Smith 400T or 450T, with 40,000 to 45,000 grains and a 10 ppm ferrous iron rating.
- Small home or soft-to-moderate water: a smaller model such as the Morton M20 to M30.
Whichever you choose, set the hardness correctly and keep salt above the water line. If something goes wrong, see our softener troubleshooting guide.
Store Brands vs SpringWell and Fleck
Online brands like SpringWell and Fleck-valve systems sell larger tanks and different control valves, often at higher prices. The store brands above have one clear advantage: their capacity and efficiency claims are verified in NSF's NSF/ANSI 44 listing, which we could not find for SpringWell or SoftPro (see our best water softeners guide). Separate-tank systems with standard valves can be easier to service and upsize later.
Frequently Asked Questions
NSF's NSF/ANSI 44 listing places Whirlpool, Rheem, Morton, Kenmore and North Star softener models under the same company, Water Channel Partners of Eagan, Minnesota. A.O. Smith and GE are listed separately.
Yes. NSF's listing includes the WHES33 for hardness reduction and as efficiency rated, with an 8 gpm flow rate.
Its manual rates the RHS32 at 33,000 grains at the maximum 14.1 lb salt dose and 13,000 grains at the efficient 2.6 lb dose. The headline number is the maximum-salt capacity.
Among these, the A.O. Smith AO-WH-SOFT models are rated for up to 10 ppm of ferrous iron. Morton M34 lists 9 ppm and Rheem RHS32 lists 8 ppm of clear-water iron.
Multiply hardness in grains per gallon by daily water use and compare with the softener's capacity at an efficient salt setting. A family using 200 gallons a day of 15 gpg water needs about 3,000 grains per day.
Only ferrous (clear-water) iron. Add 5 grains per gallon to your hardness setting for each 1 ppm of ferrous iron, and use a resin cleaner regularly. Ferric, bacterial or colloidal iron needs other treatment.
Last updated: October 2026. Sources: NSF/ANSI 44 listing, owner's manuals for Rheem RHS32, Morton M20 to M34 and A.O. Smith, retailer listing for Whirlpool.