Types of water softeners: the complete overview
Anyone looking for a water softener soon notices how wide the choice is: timer- or volume-controlled, electronic or mechanical, one tank or two, with tablets, crystals or block salt. In this overview we list all types of water softeners with salt (ion exchangers), explain how they work and help you choose the right type. Looking for a system without salt? We have written a separate article about that.
A water softener with salt (ion exchanger) is the only domestic technology that demonstrably makes your water softer.
The water softener with salt
A classic water softener contains a tank full of tiny beads: the resin. These beads hold on to the lime: when hard water flows through them, calcium and magnesium stick to the beads. The water that leaves the appliance is therefore genuinely soft. This principle is called ion exchange: calcium and magnesium are removed from the water and a little sodium is released in return.
After a while the beads are saturated with lime and need to be rinsed, as it were. This happens automatically and is called regeneration: the appliance flushes the beads with salt water made from the softener salt in the brine tank. The lime is released and disappears down the drain, after which the beads are ready for use again. That is why you need to top up the salt from time to time, in the form of salt tablets, salt crystals or granular salt.
Ion exchange is the only domestic technology that demonstrably makes water truly softer. Salt-free alternatives do not reduce hardness: the lime stays in the water, so limescale marks and the other drawbacks of hard water remain. At most, some systems try to limit scale build-up in pipes and appliances, and even for that the independent evidence is often limited. The Belgian consumer organisation Test Aankoop also confirms that ion-exchange softeners have long proven their effectiveness.
Control: when does the appliance regenerate, and how is that controlled?
Two separate questions come into play when it comes to controlling a softener. The first is what triggers the regeneration. The second is how that control is implemented technically.
Question 1: what triggers the regeneration?
- Timer-controlled: regenerates at fixed times (for example every few days), regardless of consumption. Simple and cheap, but it may regenerate too early (wasting salt and water) or too late (hard water).
- Volume-controlled (metered): measures actual consumption with a water meter and only regenerates when necessary. More economical with salt and water, and better suited to variable consumption. Slightly more expensive because of the extra hardware.
| Feature | Timer-controlled | Volume-controlled |
|---|---|---|
| Purchase price | Lower | Higher |
| Salt and water consumption | Often higher due to over-regeneration | Optimised |
| Suitable for variable consumption | Less so | Very suitable |
Question 2: how is that control implemented technically?
- Electronic: a circuit board with display and software controls the valve, the unit on top of the appliance that starts the regeneration and switches the water flows. This offers extra functions such as a holiday programme or an app, but requires power and is slightly more prone to faults.
- Mechanical: gears, cams and a rotating dial control the valve, without any electronics. Robust, hardly prone to faults and easy to repair, but without smart functions.
The classic budget softener is mechanical and timer-controlled (the timer valve with rotating dial). The modern standard is electronic and volume-controlled.
Configuration: which types are there?
Besides the control, the construction of the appliance also differs. Broadly speaking there are four configurations; which one suits you depends on the space available, your consumption and whether you need soft water 24/7.
Single tank with integrated brine tank
Resin and salt sit together in one compact appliance. Suitable for smaller homes; usually regenerates at night, when no water is being used.
Suitable for: small homes and average consumption.
Single tank with separate brine tank
The resin cylinder and brine tank are separate units. More flexible to install, often with a higher capacity and a brine tank that is easier to maintain.
Suitable for: average to high consumption.
Twin tank (duplex)
Two resin cylinders: while one is active, the other regenerates, so soft water is available 24/7. Interesting for high or continuous consumption. One nuance: a twin tank does not soften any better, it mainly ensures an uninterrupted supply; for an average family, a well-sized single softener that regenerates at night is sufficient.
Suitable for: large families, hospitality and professional use.
Compact block-salt model
Works with salt blocks instead of loose salt or tablets and fits under the kitchen sink or in a kitchen cupboard. Less storage capacity for salt, but often twin-cylinder and metered as well, and therefore suitable for households of all sizes, not just small ones.
Suitable for: little space, from small to large households.
Configurations compared
| Type of appliance | Brine tank | Resin configuration | Continuous soft water? | Suitable for |
|---|---|---|---|---|
| Single tank, integrated | In the appliance | 1 tank | No | Small homes |
| Single tank, separate brine tank | Separate | 1 tank | No | Average consumption |
| Twin tank | Separate | 2 tanks | Yes | Large families, hospitality, industry |
| Block-salt appliance (compact) | In the appliance, for blocks | 1 or 2 small tanks | Often (twin-cylinder versions) | Little space, households of all sizes |
The role of the softener salt
The quality of your soft water also depends on the salt you use. SOFT-SEL® is the water softening salt from ZOUTMAN, an independent Belgian salt company. SOFT-SEL® is available as salt tablets, salt crystals, granular salt, salt blocks and liquid salt, and complies with the European standard EN 973 type A. High purity promotes better operation and a longer service life for your appliance. Always choose a salt that suits your type of softener.
What about salt-free water softeners?
Magnetic devices, polyphosphate dosing, CO2 dosing, TAC… they promise less limescale without salt. But do they actually make your water softer? Most salt-free systems simply leave the lime in the water, and the evidence for their effectiveness varies widely.
We took a critical look at all the alternatives in Salt-free water softener: a critical look at the alternatives.
Which water softener suits your situation?
- You want less limescale and softer water throughout the house: an ion exchanger with salt is the proven choice. Preferably choose a volume-controlled (metered) appliance, correctly sized for your household and water hardness.
- Large family or continuous consumption: consider a twin tank for soft water 24/7; a single appliance is sufficient for most families.
- Little space: a compact (block-salt) model under the sink.
- Variable consumption or frequently away: an electronic, volume-controlled appliance with a holiday programme only regenerates when necessary.
- You would rather not use salt, or mainly want pure drinking water from a single tap: read our article on salt-free water softeners.
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