Quick Answer: Both are dealer-sold, and neither sells softeners on Amazon. EcoWater is the better pick for most people. It publishes detailed spec sheets, its current models include Wi-Fi monitoring, and you can buy through Costco's EcoWater program. RainSoft wins on warranty breadth. Its limited lifetime warranty covers the resin and electronics, not just the tanks, though labor isn't covered and parts carry handling charges. If you'd rather skip the in-home sale, the Kenmore 420 comes from a retail softener line whose manuals name an EcoWater-registered company as the licensed maker. If you'll install it yourself, the Fleck 5600SXT 48,000-grain is the usual choice.
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| EcoWater | RainSoft | |
|---|---|---|
| How it's sold | Local dealers; Costco member program; Home Depot | Independent authorized dealers; Home Depot |
| How the sale starts | Free in-home water test and consultation | Free in-home water test and consultation |
| Example model | ECR3700 series | EC5 series |
| Regeneration | Demand-based, learns your usage (ECR3700) | Demand-initiated (EC5) |
| Smart features | HydroLink Plus Wi-Fi app with low-salt, excess-water-use and error alerts (ECR3700) | One retailer lists an EC5 as "Wi-Fi enabled"; RainSoft's own pages don't detail it |
| Published efficiency | 5,030 grains/lb of salt at the low setting (ECR3700) | Not published on the pages we read |
| Tank warranty | Lifetime, original owner (ECR3700) | Limited lifetime, first retail purchaser |
| Valve | 10 years (ECR3700) | Limited lifetime |
| Electronics | 7 years faceplate (ECR3700) | Limited lifetime |
| Resin | Not listed separately | Covered (Ion-X resin) |
| Labor | Not in the published spec-sheet warranty | Excluded |
| Sold on Amazon? | No (parts only) | No (parts only) |
Warranty terms vary by model and dealer. These are from EcoWater's ECR3700 spec sheet and RainSoft's published warranty language.
If you're reading this, you've probably had one of these companies in your kitchen, or you're about to. Both run the same playbook: a free water test, a recommendation, a quote. The hardware from both is competent. The real differences are in how much each company puts in writing before you sign, and what the warranty actually pays for later.
We haven't owned either system. This comparison uses EcoWater's published ECR3700 spec sheet, RainSoft's published warranty terms and product lines, Costco's EcoWater program page, and a public-records summary of court filings and BBB data.
In this guide
EcoWater puts its numbers on paper
The ECR3700 spec sheet is the kind of document every softener buyer should ask for. It covers two tank sizes:
| ECR3700 | R20 | R30 |
|---|---|---|
| Capacity at mid salt dose | 18,400 grains at 7.5 lb salt | 27,100 grains at 11.0 lb salt |
| Efficiency at low salt dose | 5,030 grains/lb at 1.1 lb salt | 5,030 grains/lb at 1.6 lb salt |
| Max hardness | 40 gpg | 60 gpg |
| Max clear-water iron | 10 ppm | 12 ppm |
| Certified flow | 9 gpm | 11 gpm |
| Water used per regeneration | 27 gal | 38 gal |
Two things stand out. First, the capacities are honest and modest. EcoWater rates capacity at realistic salt doses instead of headlining a giant number that needs a heavy salt dose. Second, HydroLink Plus Wi-Fi sends phone alerts for low salt, excessive water use, system errors and service reminders, and it can sense water running to drain. That catches a stuck valve before it wastes days of water and salt.
The warranty on this model: salt and mineral tanks for the original owner's lifetime, valve body 10 years, electronic faceplate 7 years, everything else 5 years. EcoWater notes that another series (ESD2800) has shorter terms, so ask which sheet applies to your model.
Costco route: Costco members can book an EcoWater consultation through Costco. A consultant tests your water, and a local EcoWater dealer installs. Costco's page promotes "expert installation and trusted support" but doesn't publish warranty extensions, so ask the dealer to put any extra coverage in writing.
RainSoft's best card is the warranty
RainSoft is a division of Aquion, Inc. and sells through independent dealers. Its softener lines include the computer-controlled EC5 (demand-initiated) and EC4 (learns household usage) and the timer-based TC series. RainSoft holds a long list of NSF/ANSI 44 certifications through Aquion. You can check any model's listing yourself, using our guide on how to verify a softener certification.
The warranty is where RainSoft pulls ahead on paper. Its published terms are a limited lifetime warranty to the first retail purchaser, covering the treatment tank, valve, salt container, electrical components and Ion-X resin against manufacturing defects. Resin and electronics are what wear out, and many brands leave them on short terms or off the list.
Now the fine print:
- You must return the signed registration card, or the coverage may not apply.
- Labor and installation are excluded.
- Replacement parts come with a "nominal charge" covering labor, handling, packing and any retail price increase.
- It's for the first purchaser, so it doesn't follow the house if you sell.
So "lifetime" means you won't buy a new valve at full price, but you'll still pay for a service visit and handling. Compare that with how long softeners typically last (10 to 15 years is the common range) and decide what that coverage is worth to you. Our guide on how to read a water softener warranty walks through these exact clauses.
What we couldn't find: a public RainSoft spec sheet with capacity at each salt dose, grains per pound, or water used per regeneration. Ask the dealer for it. If they won't provide one, that tells you something.
The sales visit, and your three-day right
Both brands sell in your home, and that's where most complaints about dealer softeners start: long demonstrations, bundled extras like RO and air purifiers, and same-day pricing.
A few facts worth knowing before the appointment:
- The FTC Cooling-Off Rule gives you three business days to cancel most in-home sales of $25 or more, with a refund due within 10 days. The dealer must tell you about it.
- RainSoft's dealer demos have drawn public criticism. In 2015 RainSoft sued a personal finance blogger over posts criticizing a dealer's in-home demonstration. In 2018 a federal court granted summary judgment for the blogger on all counts, finding the posts were protected opinion or substantially true.
- Reputation snapshots are mixed for dealer brands generally. In early October 2026, RainSoft's BBB profile showed an A+ rating as an accredited business, with 61 complaints over three years. Treat the local dealer's reviews as more important than the national brand's.
None of that is a reason to avoid either brand. It's a reason to get both quotes in writing, take the paperwork home and compare.
Who should pick which
Pick EcoWater if:
- You want to see real specs (capacity, efficiency, water per regeneration) before you buy.
- Wi-Fi alerts for low salt and leaks matter to you.
- You're a Costco member and like having Costco in the loop.
Pick RainSoft if:
- Your local RainSoft dealer has a strong service record where you live.
- Long-term coverage on resin and electronics outweighs the parts handling fees.
- You'll actually mail in the registration card.
Pick neither if the quote bundles equipment you didn't ask for, or the price is only good tonight.
Or skip the dealer entirely
Neither brand sells softeners on Amazon. Searches there turn up only replacement parts. If you want to avoid the in-home sale, two routes make sense:
Kenmore 420. Whirlpool's softener manuals and Kenmore's 350 manual both name Water Channel Partners, a trade name registered by EcoWater Systems, as the licensed manufacturer. Whirlpool's units aren't currently sold on Amazon, so Kenmore's line is the closest thing to retail EcoWater engineering you can order there. The 420 is the 40,000-grain model, sized for 1–5 people, with IntelliSoft demand regeneration that learns your water use, a sediment pre-filter and enhanced clear-water iron reduction aimed at well water. The warranty is much shorter than a dealer unit's: 1 year full, 3 years on electronics and 10 years on the tank. There's no Wi-Fi mentioned on this model, and you install it yourself or hire a plumber. Check price on Amazon.
AFWFilters Fleck 5600SXT 48,000-grain. This is a metered, on-demand digital valve on a standard resin tank. It's the go-to DIY route for larger households or harder water than a cabinet softener handles comfortably. Parts like bypasses and replacement valve heads are sold separately, so you're not tied to one dealer for repairs. It has no app and no in-home service, and you have to set it up yourself. Check price on Amazon.
If you do go EcoWater, keep our planned guide on resetting an EcoWater softener handy for the inevitable power-outage morning.
Which quote to sign
On published information, EcoWater is the more transparent choice. It has real spec sheets, modest and honest capacity ratings, Wi-Fi monitoring and a Costco buying path. RainSoft's broad lifetime warranty is its strongest argument, but read the conditions before you count on it. Whichever you choose, the dealer matters more than the logo. And if the in-home process isn't for you, a retail or DIY softener gets you most of the way there for a lot less paperwork.