The Aquasana SimplySoft 40,000-grain softener (WH-SF40) is certified by IAPMO R&T to NSF/ANSI 44 for hardness reduction and salt efficiency. It’s a metered ion-exchange softener rated at 11 gallons a minute, sized for up to 5 people and 4 bathrooms.
The catch: The Amazon version is the softener only: the installation kit with the pre-filter costs extra, and owners say there’s no printed manual in the box.
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Is the Aquasana SimplySoft a good water softener?
Yes. It’s one of the few softeners we found on Amazon that a certifier lists: IAPMO R&T certifies the WH-SF40 to NSF/ANSI 44, the standard for residential ion-exchange softeners, for hardness reduction and as efficiency rated. That means its capacity was verified, and it removes at least 3,350 grains of hardness per pound of salt while using no more than 5 gallons of water per 1,000 grains. Aquasana rates it at 4,423 grains per pound.
It’s a true softener. Resin beads swap the calcium and magnesium in your water for sodium (or potassium, if you use potassium chloride), so scale stops forming on fixtures, glass, shower doors and inside the water heater, and soap lathers properly. It regenerates on demand: you enter your hardness and household size, and it counts the gallons used and recharges only when the resin needs it.
The weak spot is setup. It goes on your main water line, needs a drain and an outlet, and the Amazon listing is the softener alone: Aquasana sells the installation kit with the pre-filter separately there, while its own site includes a pre-filter. Several owners say the box had no printed manual, so download it before you start.
You have hard city or well water, want soft water at every tap, and can plumb in a softener or pay someone to.
Your area restricts salt-discharge softeners, your well has more than 1 ppm of iron, or you only want better-tasting drinking water.
How it scored
For softeners, treatment performance takes the place of contaminant reduction and carries the most weight in the overall score. How we checked · How we score
What does it remove?
Hardness, and that’s its certified job. It isn’t a filter for chlorine, lead or PFAS.
| What you want | SimplySoft | Notes |
|---|---|---|
| Hardness (calcium, magnesium) | Certified | IAPMO R&T, NSF/ANSI 44 |
| Salt efficiency | Certified | Efficiency rated; Aquasana rates it at 4,423 grains per pound at the 3 lb setting |
| Ferrous (clear-water) iron | Up to 1 ppm | Aquasana’s limit, not a certified claim |
| Barium, radium | No claim | Some certified softeners carry these; this one doesn’t |
| Chlorine, lead, PFAS | No | Not a filter |
| Bacteria, viruses | No | Not for unsafe water; add UV on a well |
Source: Aquasana’s WH-SF40 performance data sheet and IAPMO R&T listing WP-16886. See our hard water guide and iron guide.
How much salt does it use?
About 3.4 pounds per 1,000 gallons at 15 grains per gallon (gpg). At its rated setting it removes 4,423 grains of hardness per pound of salt, so your salt use depends on how hard your water is and how much you use. The table assumes the home softens 60,000 gallons a year, about 165 gallons a day.
| Your hardness | Salt per 1,000 gallons | Salt per year | 40 lb bags a year |
|---|---|---|---|
| 10 gpg | 2.3 lb | About 136 lb | About 3.4 |
| 15 gpg | 3.4 lb | About 204 lb | About 5 |
| 20 gpg | 4.5 lb | About 271 lb | About 7 |
Our calculation from Aquasana’s rated 4,423 grains per pound, which applies only at the 3 lb salt setting; higher settings use more salt per grain. Add 4 gpg for every ppm of iron and 8 gpg for every ppm of manganese, as Aquasana’s manual says. The brine tank holds 230 lb. To convert mg/L of hardness to gpg, divide by 17.1.
Beyond salt, Aquasana suggests a softener cleaner every 3 months and cleaning the brine tank every 2 to 3 years. If you buy the installation kit, its pre-filter needs changing every 2 months, or every 6 months with Aquasana’s low-maintenance version.
Pros and cons
What we liked
- Certified to NSF/ANSI 44 by IAPMO R&T
- Efficiency rated: 4,423 grains per pound (Aquasana)
- 11 gpm with 1-inch connections
- Regenerates by gallons used, not on a timer
- 10-year warranty on the tanks
What to know
- Installation kit and pre-filter sold separately
- Owners report no printed manual; it’s online
- Needs a drain, an outlet and cold-water plumbing
- Iron limit of 1 ppm
- Adds sodium to softened water
What owners say
Owners are mostly happy with the water. The complaints are about setup, not softening.
Often praised
- Soft water and less buildup within days
- Simple to program: hardness and household size
- Quiet regeneration and a smaller footprint than older units
Common complaints
- No printed manual in the box
- The online manual and video don’t always match
- Heavy tank; side ports use plugs, not standard fittings
Recurring themes across verified buyer reviews.
Specifications
- Model
- WH-SF40 (Amazon: WH-SF40-BASE)
- Type
- Salt-based ion-exchange softener, metered
- Sized for
- Up to 5 people and 4 bathrooms (maker)
- Flow rate
- 11.02 gpm rated, 15 psi pressure drop
- Resin
- 1 cubic foot, 10 x 35 inch tank
- Brine tank
- Holds 230 lb of salt
- Water limits
- Up to 200 gpg hardness, 1 ppm iron; pH 6.5 or higher
- Operating range
- 40 to 100°F; up to 125 psi
- Size
- 43 inches tall, 30 x 15 inch footprint
- Connections
- 1-inch male thread
- Power
- 12 V adapter, standard outlet
- Certification
- IAPMO R&T: NSF/ANSI 44 (WP-16886). Aquasana also lists NSF/ANSI/CAN 372 and CSA B483.1
- Warranty
- 5 years control valve, 10 years tanks
Alternatives worth considering
AquaTru Carafe
SpringWell FutureSoft
Common questions
Is the Aquasana SimplySoft salt-based or salt-free?
Salt-based. The WH-SF40 and WH-SF60 are ion-exchange softeners that use salt and are certified to NSF/ANSI 44. Aquasana also sells a salt-free conditioner, which doesn’t soften, so check the model number before you buy.
Can I install it myself?
Yes, if you’re comfortable cutting into your main water line. You need a drain within reach of the drain hose, a standard outlet and the fittings for your pipes; on Amazon, Aquasana sells the installation kit with the pre-filter separately. Aquasana recommends a plumber if you’re unsure. Download the manual from Aquasana’s site before you start.
Does softened water add sodium?
Yes. Aquasana says it adds about 7.5 mg of sodium per quart for each grain per gallon of hardness removed, so water at 15 gpg gets about 110 mg per quart. If you’re watching sodium, use potassium chloride, or drink from a reverse osmosis tap. See our sodium guide.
Can I use it on well water?
Yes, if the well water is safe to drink and has no more than 1 ppm of iron and a pH of 6.5 or higher. Test the well first. Add a UV system if bacteria are a risk, and treat high iron or sulfur before the softener. See our well water guide.
Does it remove chlorine, lead or PFAS?
No. It’s certified for hardness only. For drinking water, add a certified reverse osmosis system after the softener, such as the AquaTru Carafe; for chlorine taste at every tap, add a whole-house carbon filter.
The bottom line
The Aquasana SimplySoft is a certified, efficient salt softener for homes that want scale gone from every tap, the water heater included. Budget for the installation kit and a plumber if you won’t do it yourself, and add a reverse osmosis system if you also want filtered drinking water.
For the other ways to deal with hard water, see our best water filter for hard water guide.
- Certifier listings: IAPMO R&T file WP-16886 (NSF/ANSI 44-2022), Aquasana, Inc., residential cation exchange water softeners: SimplySoft WH-SF40 (11.02 gpm) and WH-SF60 (11.1 gpm), efficiency rated, reduction claim hardness. Active.
- Also searched: NSF International (NSF/ANSI 44 listings): no Aquasana softener. WQA (Aquasana): no NSF/ANSI 44 listing.
- Maker documents: Aquasana WH-SF40 and WH-SF60 performance data sheet and installation manual; SimplySoft 40,000 grain product page.
- Independent lab tests: None used.
Sources
- IAPMO R&T listing WP-16886, Aquasana, Inc.: Residential cation exchange water softeners, NSF/ANSI 44 (checked 13 Oct 2026)
- Aquasana WH-SF40 and WH-SF60 performance data sheet
- Aquasana WH-SF40 and WH-SF60 installation and owner’s manual
- Aquasana SimplySoft 40,000 grain softener page
- NSF International NSF/ANSI 44 listings
- WQA Gold Seal product directory (no Aquasana softener listing, 13 Oct 2026)
Prices as of October 14, 2026. Product prices and availability are accurate as of the date/time indicated and are subject to change. As an Amazon Associate we earn from qualifying purchases.