Quick Answer: For a family in a typical 2–3 bathroom house, get the Whirlpool WHES40E. It's rated for nearly double the service flow, holds more salt and publishes better efficiency numbers. Pick the WaterBoss 900 for a smaller home, a tight utility closet, or well water that carries grit, because its built-in filter media and shorter cabinet are real advantages there. Check your pH first: WaterBoss requires 7 or higher. For big households or very hard water, step up to a Fleck 5600SXT 48,000-grain.
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| WaterBoss 900 | Whirlpool 40,000-grain (WHES40) | |
|---|---|---|
| Advertised capacity | 36,400 grains | 40,000 grains |
| Max hardness | 90 gpg | 125 gpg |
| Max iron | 10 ppm ferrous | 10 ppm clear-water |
| Rated service flow | 4 gpm (manual) | 7.6 gpm (manual) |
| Built-in sediment media | Yes ("Power Clean" fine-mesh media) | No |
| Minimum pH | 7 | Not listed as a limit |
| Published efficiency | Not headlined | 5,094 grains/lb salt at lowest dose |
| Salt storage | 160 lb (manual) | 200 lb (retailer spec, 40K model) |
| Height | 30.75 in (manual) | about 48 in |
| Regeneration | Metered, on demand | Demand-initiated ("6th Sense") |
| Who makes it | Hague Quality Water (owned by A. O. Smith since 2017) | Made under license by Water Channel Partners (an EcoWater Systems trade name) |
| Warranty highlights | Published summaries: 5 yr mechanical/electronic, 10 yr tank, valve body, cabinet; resin and labor not covered | 1 yr full parts and labor (5 yr with Whirlpool cleaner), 3 yr control board, 10 yr tanks |
Sources: WaterBoss owner's manual and retailer listings; Whirlpool owner's manual for WHES40/WHES44 and a retailer spec sheet. WaterBoss manuals vary by printing, and an older one lists 3 years on parts.
These are the two softeners you're most likely to find at a big-box store, and on paper they look like near twins: roughly 40,000 grains, one cabinet, DIY-friendly install. In practice they suit different homes. The deciding spec isn't grain capacity, it's flow. After that come iron, pH and how much floor space you have.
We haven't installed either. Specs below come from each brand's owner's manuals, retailer spec pages and published warranty terms.
In this guide
The number that decides it: service flow
Grain capacity tells you how long between regenerations. Service flow tells you whether the shower drops off when someone starts the dishwasher.
- WaterBoss's manual rates the 900 at 4 gpm, with a 4 psi pressure drop at that flow. Peak flow is listed at 10 gpm with a 14.5 psi drop.
- Whirlpool's manual rates its 40,000-grain model at 7.6 gpm service flow, with a 20–125 psi operating range.
A shower runs around 2 gpm, a washer a few more, and a kitchen faucet another 1.5 to 2. Two showers plus the dishwasher is already past 4 gpm. The WaterBoss will still pass water at that point, but with noticeably more pressure loss. In a one- or two-bath home that rarely matters. In a busy three-bath household on a modest well pump, you'll feel it.
So: more than two people often using water at once → Whirlpool. Small household → either works.
Capacity claims vs. what you get per bag of salt
Both brands headline the capacity you get at the maximum salt dose. That isn't how you should run either one. Our explainer on what grain capacity really means covers why.
Whirlpool's manual is unusually clear about it:
| Whirlpool 40K salt dose | Capacity |
|---|---|
| 3.4 lb | 17,300 grains (5,094 grains/lb, the most efficient setting) |
| 9.0 lb | 31,600 grains |
| 15.5 lb | 40,000 grains (the headline number) |
For the WaterBoss 900, an older owner's manual we found lists 27,000 grains at 7.5 lb of salt in its high-capacity mode and 24,000 grains at 6 lb in high-efficiency mode. That's well below the 36,400 on the box. Treat those manual figures as approximate, because WaterBoss has revised its documents over the years, but the pattern is normal. Every softener gives up efficiency to reach its headline number.
Worked example. A family of four uses about 300 gallons a day on 12 gpg water. That's 3,600 grains of hardness a day.
- Whirlpool at 9 lb salt (31,600 grains) → regenerates about every 8 to 9 days
- WaterBoss 900 at 7.5 lb (about 27,000 grains) → about every 7 days
Both are reasonable. Neither is a stretch for this home. The Whirlpool simply has more headroom. Run your own numbers with our softener sizing guide.
Sediment, iron and pH: the WaterBoss quirks
Built-in filtration. WaterBoss's manual describes "Power Clean" fine-mesh filter media inside the tank alongside the resin, and the brand markets the 900 as reducing dirt and sediment. Retailers describe the filter as self-cleaning. For well water that leaves grit in aerators, that's a real plus over the Whirlpool, which expects clean water in. It doesn't replace a proper sediment filter on a sandy well.
Iron. Both claim to handle up to 10 ppm. WaterBoss says ferrous (dissolved) iron; Whirlpool says "clear water" iron, which is the same thing. Neither handles red, already-oxidized iron or iron bacteria, so a lab test comes first.
pH. WaterBoss's manual requires pH 7 or higher. Plenty of private wells run acidic, and that's hard on plumbing as well as on the softener. If yours is below 7, you'll need a neutralizer ahead of either brand. With WaterBoss, it's a stated requirement. Our guide on whether a softener changes pH explains what to expect.
Fitting it in and keeping it fed
- Height: the WaterBoss 900 is about 31 inches tall, which fits under shelves and in closets. The Whirlpool is a full-height cabinet at roughly 48 inches.
- Salt: about 160 lb of storage in the WaterBoss versus 200 lb in the Whirlpool 40K. For a family, that's the difference between one salt trip a month and a few more weeks between trips.
- Indicators: the Whirlpool has a low-salt light and a tank light. WaterBoss's display is simpler.
- Programming: both are set-and-forget once you enter hardness and time. Our planned guides on programming a WaterBoss and programming a Whirlpool softener walk through setup.
Warranty and who stands behind it
Whirlpool's warranty is short at the start and longer if you play along: 1 year full parts and labor, 3 years on the electronic control board, 10 years on the salt and mineral tanks. Parts and labor extend to 5 years if you use Whirlpool's softener cleaner, one bottle every four months, and keep receipts. Coverage requires pressure under 125 psi and water under 120°F. Whirlpool doesn't make the units itself. They're manufactured under license by Water Channel Partners, a trade name registered by EcoWater Systems.
WaterBoss belongs to Hague Quality Water, which A. O. Smith bought in 2017. Published warranty summaries list 5 years on mechanical and electronic parts and 10 years on the media tank, control valve body and brine cabinet. Resin and labor aren't covered. An older manual we read listed 3 years on parts, so check the card in your box.
On paper, WaterBoss gives you longer parts coverage without the cleaner-subscription condition. Whirlpool gives you first-year labor.
Pick by household
- 1–2 people, condo or small house, city water → WaterBoss 900, or the 22,000-grain WaterBoss if hardness is modest.
- Cabin or small home on a gritty well with pH 7+ → WaterBoss 900.
- Family of 3–5, 2–3 baths, city or clean well water → Whirlpool WHES40E.
- Acidic well (pH under 7) → add a neutralizer first. Then lean Whirlpool, or go custom.
- 5+ people, 3+ baths or hardness above about 20 gpg → skip both and look at the Fleck below.
Alternatives in the same aisle (and one step up)
WaterBoss 700 (model 74011) is the 22,000-grain sibling, with the same built-in iron and sediment filtering the brand advertises on the 900. Per the manual it has 0.7 cubic feet of resin, handles up to 70 gpg and stands under 26 inches tall. It's a good match for a one-bath condo or cabin. It's too small for families. Check price on Amazon.
Kenmore 350 is a 32,000-grain cabinet softener from the same big-box aisle. Its IntelliSoft control learns your water use and regenerates only when needed, much like Whirlpool's demand-initiated control. The listing says it's sized for 1–4 people, reduces clear-water iron, uses a 3/4-inch valve, and has a digital display that shows flow rate and salt level. The warranty is 1 year full, 3 years on electronics and 10 years on the tank. It's right for two or three people on moderate hardness. Kenmore doesn't publish a service flow rate in the listing, so check it if you have several bathrooms. Check price on Amazon.
AFWFilters Fleck 5600SXT 48,000-grain isn't a cabinet unit. It's a separate resin tank and brine tank with a metered digital Fleck valve. It's more work to install and takes more floor space, but it's the step up when a house has outgrown both big-box options. Replacement valve heads and bypasses are sold separately, so it's easy to repair down the road. Check price on Amazon.
Flow first, then everything else
The Whirlpool is the better all-round softener for a family. It has nearly double the rated service flow, more salt storage, a higher hardness limit and transparent efficiency numbers. The WaterBoss 900 earns its place in smaller homes, tight spaces and on gritty wells with neutral or alkaline water, thanks to its built-in filter media and short cabinet. Measure your pH and count your bathrooms, and the choice usually makes itself.