A twin-tank water softener is a type of water softener system that has two resin tanks and one brine tank. It is also called a “dual tank” water softener or “double tank.”

The dual tank ion exchange water softener is used where downtime/breakup of the water softener is an issue, or you have a high usage of water, and your water has high hardness.
A twin tank is ideal for very large homes with many people, very high hardness levels, or commercial applications
Twin-tank water softener comparisons
Name | Image | Grain capacity | Buy here | |
---|---|---|---|---|
1 | Fleck 9100SXT Dual tank water softener 110K | 110,000 | Buy from Amazon | |
2 | Fleck 32K Digital Dual Tank Alternating IRON PRO Water Softener with Fleck 9100SXT | 32,000 | Buy from Amazon | |
3 | AFWFilters Dual tank 110,000 grain | 110,000 | Buy from Amazon | |
4 | DuraWater USA Fleck 9100SXT Almond | 32,000 | Buy from Amazon | |
5 | Discount Water Softeners Genesis Duo | 32,000 | Buy from Amazon |
How does a twin-tank water softener work?
Hard water gets into the first resin tank that contains resin beads while the second resin tank is reserved. The resin beads are negatively charged and hard water is positively charged.
The negatively charged resin beads attract positively charged ions in the hard water through a process called cation exchange/ion exchange.
Minerals that make water hard remain on the resin beads, and soft water passes through the resin tank ready for human use.
After some time, the resin beads are overcoated/saturated with hard water minerals. During this time the beads do not operate effectively they require to be cleaned to provide soft water.
The process of cleaning the resin beads is called regeneration.
During regeneration time the system switches to the second resin tank. The regeneration process takes place in the first resin tank.
What takes place in an ion exchange water softener with two tanks?
As a result, conditioned water is continuously supplied without interruption or downtime when one tank is softening water and the other is regenerating.
Make sure you have adequate room to install a dual-tank water softener before you buy one. Some dual-tank water softeners need the energy to operate, so make sure the power supply is nearby.
Twin-tank water softener reviews
The Fleck 9100SXT is a dual-tank system, so you never run out of softened water.
It is capable of removing up to 110,000 grains of hardness between regeneration cycles making it ideal for a home with many peoples, very high hardness levels, or commercial application
The package includes riser tubes with distributor baskets of 3.5 ft3 high capacity resin per tank, 14′′ x 65′′ resin tanks (2), a Fleck 9100SXT digital metered control head, and a larger round brine tank that measures approximately 18′′ by 40′′ and holds approximately 350 lb of salt.
It removes iron up to 6-8ppm.
more capacity of the fleck dual tank system
32K capacity per tank with Fleck Digital 9100SXT.
The tank has a warranty of 10 years and Fleck 9100SXT Digital Metered Control Head has a warranty of 5 years.
The Genesis Duo is a water softener with a whole house filter using catalytic carbon capable of removing chlorine and chloramine.
It has a variety of capacities from 32000, 40000, and 48000 grains.
The control head is covered by a 10-year warranty, and the resin and brine tanks are covered by a lifetime warranty. It uses up-flow regeneration.
The AFWFilters twin-tank uses a Fleck 9100SXT Digital Metered Control Head.
The dual tank system ensures that soft water is available around-the-clock every day because while one tank is regenerating, the other tank is softening hard water.
This model has a capacity of 110,000 grains which is ideal for large homes with many people, very high hardness levels, or commercial applications.
The system comes complete with
- Two 14′′ x 65′′ polyglass tank resin tanks
- Two Riser tubes with distributor baskets
- 3.5ft3 of high-capacity resin per tank.
- Larger Round 18″x40″ Brine Tank which holds approximately 350 lb of salt and DIY Installation.
DuraWater is a 32,000-grain twin tank system featuring the new Fleck 9100 valve.
Genuine units It comes with an iron hardness plus test kit, 2.0 cubic feet of resin, 32,000 grain capacity per tank (total of 64,000 grains), a fleck 9100SXT controller, two (10×40) mineral almond tanks, a salt tank, bypass, a (14X34) brine tank with safety float, and an upgraded paddle wheel meter.
The resin tank is sized at 1040′′ and comes loaded with resin for easy installation. It comes in a variety of shades, including almond, black, and blue.
The benefit of the twin-tank water softener is
Provide soft water throughout, not unlike a single-tank water softener that provides hard water during regeneration.
Hard water is not a problem when using a twin-tank water softener because while one resin tank is regenerating, the other one supplies soft water to the home.
Twin tank systems are mostly used in areas such as:
- Hospitals
- Hotel industries
- Large families
- Education centers