Best Non-Electric and Dual-Tank Water Softeners
Quick answer: a single-tank softener sends hard water to the house while it regenerates, usually overnight. A dual-tank (twin) softener keeps one tank in service while the other regenerates, so you have soft water around the clock. Most twin systems still need electricity; Kinetico’s Premier Series is the non-electric option we found, powered by the flow of water and sold through dealers. For a do-it-yourself twin, the DuraWater Fleck 9100SXT is the easiest to buy online. Most homes don’t need either: if nobody uses water during the night, a standard single-tank softener is enough.
Our picks:
- Best non-electric: Kinetico Premier XP (through a dealer)
- Best do-it-yourself twin tank: DuraWater Fleck 9100SXT, 48,000 grains
- Best twin tank from a dealer: a system on the Clack WS1TT valve
- Non-electric for RVs: On The Go Double Standard
How we chose: we haven’t installed or tested these softeners ourselves. We used Pentair’s, Clack’s and Kinetico’s own specifications and warranty documents, and say where details come only from a seller’s listing.
Single tank, twin tank or non-electric?
| Single tank | Twin tank (electric) | Non-electric twin | |
|---|---|---|---|
| Soft water during regeneration | No; hard water bypasses to the house | Yes; the other tank stays in service | Yes; one tank is always ready |
| Power | Needs an outlet | Needs an outlet | None; moving water powers it |
| When it regenerates | Usually at night (2:00 a.m. by default on Whirlpool, Rheem and Fleck) | Any time a tank is used up | Based on metered water use |
| Space | One resin tank and a brine tank (or one cabinet) | Two resin tanks and a brine tank | Two resin tanks and a brine tank |
| Where to buy | Online, stores, dealers | Online (Fleck 9100SXT) or dealers (Clack WS1TT) | Kinetico dealers |
From Pentair’s Fleck 9100 technical sheet, Clack’s WS1TT page, Kinetico’s Premier XP page, and Whirlpool’s and Rheem’s manuals (see our regeneration guide).
How a dual-tank softener works
A twin softener has two resin tanks, one control valve and one brine tank. The DuraWater system, for example, pairs two 10 × 54-inch resin tanks with a single 14 × 36-inch brine tank, according to its listing.
- One tank softens. Pentair says its Fleck 9100 provides continuous soft water with only one tank in use, while the other is regenerating or on standby.
- The meter counts. When the tank in service has treated its set number of gallons, the valve switches to the standby tank.
- The used tank can regenerate right away. Pentair says the 9100 regenerates with softened water, and Clack lists treated-water refill and regeneration cycles on the WS1TT, which can start a regeneration immediately or at a set time. It doesn’t have to wait for the middle of the night.
- It waits on standby. The fresh tank sits ready until the other one is used up.
For how each tank softens water, see how a water softener works.
How a non-electric softener works
Kinetico says its Premier Series softeners are non-electric twin-tank systems: moving water powers them, so there are no timers or computers to set. They meter water use and regenerate based on actual use, and one tank is always ready to deliver soft water. Its Overdrive models (S650 OD XP and Q850 OD XP) can run water through both tanks at once for higher flow.
Non-electric still means salt: these are salt-based ion exchange softeners with a brine tank and a drain line. If you want no salt and no power, a salt-free conditioner needs neither, but it reduces scale rather than softening the water. See salt-free water softeners.
Who needs soft water around the clock?
- Homes that use water at night. Rheem says water drawn during a regeneration bypasses the softener, and Whirlpool says using hot water then refills the water heater with hard water. If someone showers or runs laundry at 2:00 a.m., a twin avoids that.
- Large or busy households. A twin can regenerate whenever a tank is used up, instead of waiting for a set time.
- Small businesses and rentals with water use at all hours.
- Homes without a nearby outlet where the water line comes in: a non-electric softener needs no power.
If none of these fit, a single-tank softener set to regenerate overnight does the same job for less space. See the best water softeners and size it with our size calculator.
Do you need a twin-tank or non-electric softener?
Answer five questions to see which type fits your home.
Answer the questions to see which type fits.
How it works: overnight water use points to a twin tank; no outlet, or frequent outages on city water, points to a non-electric softener. On a private well, the pump needs power anyway, so outages alone don’t call for a non-electric softener.
Our picks
Kinetico Premier XP
The non-electric twin-tank softener we found from a major brand. Moving water drives the valve and meter, one tank is always ready, and the Overdrive models can use both tanks at once for higher flow.
- Warranty: Kinetico’s 2021 warranty covers all parts, resin and tanks on the Premier Series for 10 years, parts only
- Sold: through local authorized Kinetico dealers, who arrange a free water test
Good to know: the warranty doesn’t cover labor or freight. Kinetico calls the S650 OD XP and Q850 OD XP the world’s most efficient softeners, based on WQA testing. Compare it with other brands in our brands guide.
See it at KineticoDuraWater Fleck 9100SXT twin tank, 48,000 grains
A complete twin system on Pentair’s Fleck 9100SXT metered valve, shipped with the resin already loaded.
- Tanks: two 10 × 54-inch resin tanks with 1.5 cu ft of resin each; 14 × 36-inch brine tank with safety float (listing)
- Capacity: 48,000 grains per tank (listing)
- Valve flow: about 20 gpm continuous for the 1-inch Fleck 9100 (Pentair, 4.5 m³/h at 1 bar drop)
- Includes: 1-inch bypass (listing)
Good to know: Pentair recommends 6 to 16-inch softener tanks for the 9100, and the valve needs a 24-volt power supply. Two resin tanks plus a brine tank need more floor space than a single-tank system.
Check price on AmazonA system on the Clack WS1TT valve
Clack’s twin alternating valve, which water treatment dealers build into complete systems. It has more flow and handles bigger tanks than the Fleck 9100.
- Flow: 28 gpm service, 15 gpm backwash with meter and bypass
- Tanks: softeners 6 to 21 inches across
- Regeneration: meter immediate, meter delayed, time clock delayed or pressure differential
- Certified: NSF/ANSI 44, NSF/ANSI/CAN 61 and 372
Good to know: like other Clack valves, it’s sold through dealers rather than to homeowners. See Clack WS1 vs Fleck 5600SXT.
See the WS1TT at ClackOn The Go Double Standard portable softener
A portable 16,000-grain softener you recharge by hand with table salt, with no electricity or tools needed. The listing says it’s made for RVs, not house plumbing.
Good to know: see our RV softener guide for how often to recharge it.
Check price on AmazonBefore you buy
- Floor space. Plan for two resin tanks and a brine tank side by side.
- Plumbing. Pentair says the 9100 comes with PVC pipes to connect the second tank.
- Power. Electric twin valves run on low-voltage power supplies: 24 volts for the Fleck 9100 and 15 volts DC for Clack. Clack’s battery keeps the clock running for 8 hours in a power cut.
- Wells and outages. A well pump needs electricity, so in a power cut you’ll lose water pressure whatever softener you have.
Frequently asked questions
Do non-electric water softeners work?
Yes. Kinetico’s non-electric softeners are salt-based ion exchange systems like any other; the flow of water drives the valve and meter instead of a motor and circuit board.
Is a dual-tank water softener worth it?
If anyone in your home uses water during the night, or you need soft water at all hours, yes. Otherwise a single tank that regenerates overnight does the same job in less space.
Can I add a second tank to my softener?
Not with a standard single-tank valve. A twin system needs a twin valve, such as the Fleck 9100 or Clack WS1TT, that switches between the tanks.
Do salt-free systems need electricity?
The salt-free conditioners in our salt-free guide need no drain, brine or electricity, but they prevent scale rather than soften the water.
Related guides
- Best water softeners
- Water softener regeneration
- Best water softener brands
- How a water softener works
Sources
- Pentair, Fleck 9100 twin valve technical sheet.
- Clack Corporation, WS1 Twin Alternating Water Specialist Valve, checked October 2026.
- Kinetico, Premier XP and Limited Warranty for Residential Applications (2021).
- Whirlpool, WHES48 manual, and Rheem, RHS18 manual: regeneration time and water use during regeneration.
- Amazon listings for the DuraWater Fleck 9100SXT and On The Go Double Standard, checked October 2026.