Water Softening System: Review & Recommendations


You notice little by little that the water container is slightly discoloured on the inside and the glass looks “milky”? Then you should think about buying a water softener. With such a system you can decalcify your water, which is obviously urgently necessary, as the example of the coffee machine shows. What alternatives are there to water softeners? What different types of softening plants are available for you to buy?

Answers to the most frequently asked questions can be found here in the big softening plant test 2020. we introduce you to various softening plants to make your purchase decision easier. You will also find helpful tips and tricks in our guide on how often you need to regenerate your softener. No matter which plant you decide on, we will explain the advantages and disadvantages of the different types.

The most important facts in brief

  • A softening plant is responsible for removing lime from drinking water. Alternatively, you can also have a lime catalyst or a reverse osmosis system installed.
  • Depending on the design, a distinction is made between softening by ion exchange, chemical softening and physical softening.
  • Before buying a softening plant, you should check important quality criteria such as the operating pressure, the size of the salt container and DVGW certification.

Softening plant test: editorial favourites

  • The best all-round softening plant
  • The best softening plant with ion exchange for small households
  • The best softening plant with ion exchange for large households
  • The best physical limescale protection system

The best all-round softening plant

The Aqmos FM-60 water softener is suitable for households of up to 5 persons and softens up to 6000 litres of water per regeneration cycle at 10°dH water quality. The plant operates according to the ion exchange process. This means that it exchanges the “hardness minerals” calcium and magnesium with sodium ions. The lime is removed and soft water is produced.

The Aqmos FM-60 consists of a GRP pressure bottle filled with high-quality ion exchange resin, cabinet housing for a salt reserve of max. 70 kg, quantity-controlled central control valve type FLECK 5600, an integrated fine blending valve, an extraction device and a connecting line to the central control valve.

The best softening plant with ion exchange for small households

The Water2buy water softener is a softening system that is delivered including a bypass valve. The low-noise and automatic meter softener is ideal for a small household for up to 4 people and delivers an average of 1250 litres of soft water daily.  The softener works according to the ion exchange method and is suitable for indoor and outdoor use.

The particularly simple installation and the perfect functioning of the system has impressed numerous customers. Customer service is also rated as very good. Buyers are also impressed by the fact that the unit ensures lime-free water for a very long time.

The best softening plant with ion exchange for large households

The Water2Buy AS800-W2B800 weighs 29 kg with dimensions of 22.5 x 47.5 x 111 cm. The softening plant works with the ion exchange method. This means it exchanges the “hardness minerals” calcium and magnesium with sodium ions. The lime is thus removed and the result is soft water. The plant has a display for control. This makes the handling easier for the layman.

The system can also be used for very large households of up to 12 people. The manufacturer recommends a maximum number of users of 12 persons. This is partly due to the water flow per hour, which is probably between 2 and 5 m³ per hour. This allows several people to use water at the same time without any problems.

The best physical limescale protection system

The PKS 2000 plus X magnetic field generator ensures that even old lime deposits can be removed and flushed out. The device is variably adjustable, but also has an automatic function, whereby it is not necessary to intervene in the pipe system. The product is suitable for a water consumption of up to 5 cubic metres per hour.

Customers are delighted that lime stains have been noticeably reduced and kitchen appliances such as coffee machines and kettles are working more smoothly. Buyers also notice that the water hardness has improved quickly and permanently after connecting the appliance.

Advisor: Questions you should deal with before you buy a softening plant

When is a water softener useful?

Decalcifying the water is useful if you live in an area with very hard water above 21°dH. How to determine the hardness of the water is described in more detail in the “Trivia” section. Water above 14°dH is classified as hard, but according to the Bavarian State Office for Health and Food Safety, softening is only recommended in warm water areas.
Furthermore, the recommendation there is generally only to equip the water supply of the washing machine and the hot water installation with softening devices.

Which descaling system should I buy?

At this point at the latest, the question arises for many buyers as to which softening plant is the best. Besides test results we can give you a general tip.
Before buying, check whether the unit of your choice has DVGW certification. This not only certifies compliance with the technical and hygienic requirements according to Worksheet W 510, but also the most important thing – the effectiveness of your system according to Worksheet W 512.
The follow-up costs of the system, such as salt consumption, can also be decisive.
In addition, you must of course ensure that the connection is compatible with your water supply at home, as there are appliances with a pipe diameter of one or two inches, one inch being the standard.
The size of the system must also fit – not only in terms of the space it takes up. The capacity of the system must match the number of consumers.
Technically enthusiastic users will enjoy a smart softener with a connection to an app, while budget-conscious families are more likely to opt for an easy-care appliance with a large salt container.

DVGW certification is important because you can be sure that the technical and hygienic requirements have been tested.

What does a water softener cost?

Depending on which requirements the system has to meet, one should expect a medium three-digit to a medium four-digit amount for the device. The prices of water softeners vary greatly depending on which process is used. The design of the plant also plays a role.

In order to save money you should therefore consider very carefully whether you really need a central house system or whether a decentralized water treatment would be a better solution. When making this calculation, however, it is important to note that the costs for installation by a specialist company are not yet included.

Where can I buy water softeners?

Water softeners can be purchased directly from the manufacturer or from specialist dealers. The manufacturers “Grünbeck”, “BWT”, “Judo”, “Eckstein” and “Lindsay” have established themselves firmly on the market in Germany.
Meanwhile, softening plants can also be found in the product range of many online platforms such as amazon.de or ebay.de.
All plants presented on this page are provided with a link so that you can buy them directly if you are interested. The advantage of buying in a specialized trade is that you already have a contact to the company that will install the plant.
In terms of advice, the online trade has now caught up well and offers a variety of possibilities such as telephone hotlines or service chats. Here you will also find a larger selection and can get a better view of the different prices.

What are the alternatives to softening plants?

As an alternative to a conventional decalcification system, you can also have a lime catalyst or a reverse osmosis system installed.
Lime catalyst
The lime catalyst works similarly to an ion exchanger with a granulate, but in this process nothing is released into or absorbed from the water.
Decalcification takes place through a reaction in which seed crystals are formed. These are passed on in the drinking water and can no longer settle.
The advantages of this process are that nothing is changed in the composition of the water and the systems are very easy to maintain. Apart from a granulate change every few years (depending on water hardness and consumption), no further maintenance or regeneration is required.
Reverse osmosis plant
Reverse osmosis systems can be used both centrally and decentrally. The water is pressed with pressure through a semi-permeable membrane.
The unwanted lime ions do not fit through the membrane because they are too large and therefore remain behind.
This solution is called concentrate. The smaller water molecules can pass the membrane. The softened water is called permeate.
Disadvantages of reverse osmosis are that not only the lime but also all other important minerals are removed from the water, while undesirable substances, which are however well water-soluble, are transported further.
At the membranes, major germ problems can occur, and the membrane pores can also easily be clogged by particles. In addition, water softening by reverse osmosis consumes 3 – 25 litres of drinking water per desalinated litre.

Decision: What types of water softeners are available and which one is right for you?

Softening plants can be divided into the following three main categories depending on the softening process:

  • Softening by ion exchange
  • Chemical lime protection plant
  • Physical lime protection system

Differences also exist in the design of the plant.

There are centralised domestic water softening systems with which the entire drinking water can be softened up to decentralised systems which are only used selectively, for example to protect the washing machine.

These exist in variants for individual apartments, single-family homes and apartment buildings. But decalcification systems are not only offered for private households, they are also available as large industrial plants.

How does softening by an ion exchanger work and what are its advantages and disadvantages?

In the field of ion exchangers, one must first distinguish between cation and anion exchangers.

While anion exchangers are used to filter nitrate from the water, cation exchangers are used to remove calcium and mag

In both processes, the respective undesirable substances are replaced by sodium chloride ions. This ion exchange gives the softening method its name.

Such a plant usually consists of a cabinet (that is why it is sometimes called a “cabinet”) in which an ion exchanger in column or ball form is placed. Duplex plants have two ion exchangers, which means that they can supply lime-free water even during the regeneration period of the plant, as only one of the two exchangers is active alternately at any one time.


Reliable effectiveness
Easy handling
Equipment available for every need


Maintenance effort and follow-up costs due to regeneration

The greatest advantage of this method is its proven and reliable effectiveness. Pipelines, fittings and technical equipment such as coffee machines or dishwashers are protected against calcification.

This reduces the maintenance effort, the units can work more effectively again as the lime deposits form an obstructive insulating layer and their service life can be extended.

Critics, however, criticize the addition of salt, which could have a negative effect on the health of hypertension patients, for example. But (NaCl) salt is not added to drinking water. The regeneration salt (NaCl) is used to regenerate the softening granulate. The Ca from the lime combines with the Cl, resulting in CaCl salt. This is also called “neutral salt” and does not pollute the environment.

But the decalcification system must be maintained. A regular supply of regeneration salt is necessary, which not only requires maintenance but also entails follow-up costs.

A clear advantage is that unwanted substances are replaced by sodium chloride ions.

How does a chemical lime protection system work and what are its advantages and disadvantages?

In chemical water softening processes, two basic methods must be distinguished. On the one hand there is chemical water softening by cation exchange and on the other hand there is the so-called complexing.

In both processes chemicals are added to the water, which form chemical compounds with the alkaline earth ions (i.e. the “lime”).

As a result, the hard water behaves like soft water and no deposits are formed, although the lime is actually still present in the water. For this reason, the processes are less called “softening” and more called “hardness stabilisation”.

Zeolite A and phyllosilicates are used in most detergents today. They cause a cation exchange. In the case of complexation, a central atom (in our case again the “lime”) which has at least one free electron pair is surrounded by the molecules of the added substances and thus can no longer be deposited.


Proven effectiveness
Stable pH value of the water
Especially suitable for galvanized pipes


Over- or underdosing due to poor maintenance
Germ formation is promoted
Possible environmental damage due to eutrophication

These substances include phosphates, ethylenediaminetetraacetate (EDTA), nitrilotriacetic acid (NTA) and citrate, the salt of citric acid, which are also used in detergents.

The heat of the water also has an influence on the lime deposits, since the solubility of calcium and magnesium decreases with increasing temperature. This is why a particularly large number of lime deposits are formed when the water is heated.

Not exceeding the obligatory upper limit of 60°C in the domestic installation has a positive effect not only on energy saving but also on the prevention of calcification.

A phosphate dosing system is particularly advisable for galvanized pipes, as the water acquires an acidic pH value through softening with an ion exchanger and can therefore become aggressive towards zinc.

This can be prevented with a phosphate supply. The disadvantages of chemical water softening include the risk of over- or under-dosing in poorly maintained systems. This can have serious effects on water quality and the environment.

Phosphates promote the eutrophication of waters. They also promote germ growth, so microbiologically safe drinking water is a basic requirement. The microbiological quality of the water must always be monitored, otherwise uncontrollable germ contamination of the drinking water can occur.

How does a physical lime protection system work and what are its advantages and disadvantages?

Plants for physical water softening are also called physical lime converters. They work magnetically, electrically or by a combination of both methods.

The electrical water decalcification is carried out via electrolysis with a subsequent undervoltage separation. An electric circuit with a voltage of at least 1.23V is formed.

At the cathode, the electrode at the negative pole, hydroxide ions are formed which cause the pH value of the water in their area to increase. At the anode, the electrode at the positive pole, hydrogen ions accumulate.

The water gets out of balance between lime and carbonic acid (hydrogen carbonate), causing the calcium carbonate to precipitate.

This is where the undervoltage separation comes into play. It operates at a voltage below the decomposition voltage and causes oxygen to be converted into hydroxide ions at the cathode while oxygen and hydrogen ions accumulate at the anode.

The hydrogen carbonate ions present in the water react with the hydrogen ions to form free carbonic acid, supersaturation takes place again at the poles and lime precipitation is thus maintained.


No supply of chemicals
Minerals remain in the water


Effectiveness highly controversial

Precipitated lime is called “seed” or “seed crystal” because the subsequently precipitated lime can adhere well to it. The electrodes break up the lime lumps again by charge reversal, but these lime particles are then too large to be able to attach themselves again and are removed with the water.

Magnetic decalcification systems are often offered in combination with an electronic component to create a magnetic field with electricity.

However, pure permanent magnets are also available. In terms of their mode of action, just like electrolysis, they cause a structural change in the calcium and magnesium ions so that they are physically precipitated.

The great advantage of physical water softening is that nothing is added to or removed from the water. However, the effectiveness of these systems is highly controversial, as a reproduction of successful experiments has so far not been possible due to too imprecise descriptions of the experimental set-ups. Furthermore, it is not officially possible to speak of softening the water, as no hardness is removed from the water in this process.

This is also confirmed by Stiftung Warentest and the Bavarian State Office for Health and Food Safety. For magnetic field systems, there is no certification of effectiveness according to the requirements of DVGW Code of Practice W 512.

Purchase criteria: With these factors you can compare and evaluate softening plants

In this section we would like to familiarize you with the different criteria that can help you to find the right softening plant for your needs.

These relevant purchase criteria include

  • The unit size
  • The operating pressure
  • The type of regeneration control
  • The size of the salt container
  • The DVGW – Certification
  • The design of the plant
  • Other performance aspects
  • Various environmental aspects

The individual criteria are explained in more detail below so that they can serve as a good basis for comparison before a purchase.

In our comparison table, we have used these criteria to compare currently popular decalcification systems.

The unit size

A central house decalcification system is installed at the house installation (usually in the basement of the house). The space available there imposes initial restrictions in terms of size when selecting a system.

In decentralised solutions, the descaling system can also be installed under the sink in the kitchen, for example, where there is usually very little space for additional equipment next to the drain pipes. Space-saving cabinet systems are therefore particularly recommended here.

Since the size of the units also has a great impact on other relevant criteria before a purchase (for example the salt tank or the softening capacity) one should consider carefully whether it makes sense, especially for a large household with a high water demand, to create a little more space for the unit to ensure an optimal supply of softened water.

The operating pressure

In order to work properly, the water leading to the system needs a certain minimum pressure. This pressure depends, for example, on the height at which the system is to be installed.

However, the maximum pressure of the water must also be observed, as too high a water pressure can damage the system.

The minimum and maximum operating pressure of the system can be found in the technical data sheet in the operating manual, which should be included in the scope of delivery. Otherwise you can also order them from the manufacturer or, in the case of the most common models, often download them from the Internet as PDF files.

The type of regeneration control

For plants which operate according to the ion exchange process and therefore require regeneration, it is important to consider how these are controlled, i.e. via which condition the regeneration of the resin is triggered. Basically, a distinction can be made here between quantity-controlled and time-controlled plants.

Time-controlled plants start the regeneration of the ion exchange resin after a pre-set period of time independent of the actual consumption.

Volume-controlled (also volumetric) softening plants, on the other hand, trigger regeneration of the resin after consumption of a set quantity of soft water.

In most systems, regeneration is triggered at night so that soft water is always available during the day and because less water is used at night in most cases, it is not so important if small quantities of undecalcified water are fed through the pipes of the house

In addition, modern decalcification plants with volume control for hygienic reasons are also equipped with a fully automatic time-based forced regeneration to prevent the formation of germs in the exchange resin if the volumetric regeneration is not triggered for a longer period of time (e.g. when the residents are on holiday).

The size of the salt container

At first glance, the size of the salt tank may not appear to be a direct purchasing decision, but for reasons of convenience it should also be included in the assessment of the systems.

A large salt supply is simply practical and increases the comfort of the system, as it means that you need to refill less often. On the other hand, the size of the salt container also affects the size of the installation, so that if there is not much space, you may have to resort to a smaller solution.

When comparing the capacity of the salt tank you should not only look at the actual volume, but also take into account how much salt is used during regeneration and how often it takes place. This is the only way to draw an absolute direct comparison between the comfort of the systems in terms of refilling.

The DVGW – Certification

The DVGW certificate stands for tested quality and effectiveness of softening plants and is recognised by the German Gas and Water Association. It serves as a seal of quality and guarantees the purchase of a reliable and high-quality product.

This includes compliance with the hygienic and technical requirements according to Worksheet W 510 and the effectiveness test according to Worksheet W 512.

Among other things, this includes regulations for installation, the guarantee of drinking water quality and the integration of a technical non-return valve that must be installed in the system.

Such protection of the public drinking water supply is prescribed by law, so a so-called pipe isolator must be retrofitted to a non-certified system, so the additional costs incurred must be taken into account in the price comparison.

Buying a system without the DVGW test mark is often cheaper, but also carries the risk that the system is not hygienically and technically perfect or does not fulfil its purpose due to a lack of effectiveness. The additional costs for the installation of a non-return valve usually add up to a total amount for which you would have received a DVGW-tested system directly.

As there are also some fraudsters in the field of water softening processes, you should always do a lot of research, make comparisons and obtain experience reports before buying a system without DVGW certification in order not to lose your money and regret the purchase.

The design of the plant

When designing the plant, the softening capacity of the water and the number of people must be taken into account in order to choose the right plant for individual requirements.

Depending on the size of the plant and the hardness of the water, the water capacity that can be softened daily varies. If a household does not know the water demand in litres, the number of persons helps as a rough guide to buy neither a too big nor a too small softening plant.

In our comparison table you can find softening plants with a design for up to 10 persons. For particularly large households, for example in large apartment buildings, the use of an Indust

Other performance aspects

Further performance aspects that are relevant for a purchase decision include the regeneration time and the other technical equipment of the plant.

The regeneration time is the time during which the softening plant regenerates the softener resin with salt. For the units in our comparison table it varies between 17 and 64 minutes. During this time, softened water is only available in a duplex system.

Mostly the regeneration is carried out during the night hours, so that no or only little water is needed at this time. If you still want to have lime-free water 24 hours a day, you should use a duplex system.

Further interesting equipment features can be systems with smart home features such as WLAN connection and app control, especially for technology enthusiasts.

Various environmental aspects

Not least for cost reasons, environmental aspects such as waste water, salt and electricity consumption must also be considered before deciding on a particular plant.

Like any electrical appliance, a softening plant consumes electricity, so this consumption must be included as a running cost factor. The two magnetic field generators are particularly economical in our comparison. In the case of the ion exchange systems, the power consumption varies between 2.6 and 8 watts.

Each regeneration uses not only salt but also water. The basic consumption per regeneration depends on the device for both aspects.

However, in the case of volume-controlled systems, it is also related to the water demand of the household due to the frequency with which regeneration takes place.

In most cases, the following applies: the longer the regeneration takes, the more water is consumed. If the water consumption of a plant is not specified, the regeneration time can be used as an indication, although exceptions may occur. However, the respective salt consumption is separate from this, which is mainly related to the water hardness.

Trivia: Worth knowing facts about water hardness and softening plants

How often do I have to regenerate the softener?

The resin of a plant in which the water is decalcified via ion exchange must be regenerated every three to seven days. Factors influencing the frequency are the water consumption and the hardness of the water.

Depending on the plant, regeneration takes between 15 and 50 minutes and is usually stopped during the night. If you do not have a duplex plant, no lime-free water is available during regeneration, so as little water as possible should be used during this time.

How do I disinfect my softening plant?

In order to ensure the hygiene of the system, you have the choice between thermal, chemical or UV disinfection. Since the disinfection process with UV light is not suitable for domestic use due to its complexity, the other two methods are described below.

For chemical disinfection of the decalcification system, either chlorine tablets can be used or a chlorine cell can be installed, which has the advantage that it also automatically disinfects the system with each regeneration.

An alternative is thermal disinfection, in which the entire domestic installation is flushed with at least 70°C. To ensure that germs and bacteria are effectively boiled off everywhere, the water must flow through each tapping point for at least three minutes. However, the heat load during frequent use can cause corrosion damage to the pipes.

Is lime in water harmful and why do I need a descaling system?

Lime occurs naturally in our water and is in principle not harmful. However, if there is too much of it, it can have some negative effects, which can be avoided by using a water softener.

Deposited lime acts as an insulating layer which increases the energy consumption. Stubborn limescale can lead to defects in technical appliances such as washing machines, dishwashers, heating systems or coffee machines, which require repair or complete replacement of the appliance.

Lime deposits on fittings or ceramics not only look unkempt, they are also very difficult to remove and attack the material.

Softer water thus helps to protect the environment because less water, detergent and cleaning products are needed. Tea and coffee drinkers appreciate soft water because it allows the aromas to develop better.

Does the salt of the softener harm my health?

According to the WHO, a sodium content of 200mg/L in drinking water is basically harmless. However, if a system is incorrectly set, this value may be exceeded.

This poses a health risk, especially for patients with high blood pressure. Therefore, for this special group of people, a different softening procedure is recommended.

What is the lifetime of a softening plant?

The average service life of the plants is stated to be at least 25 years.

Despite the quite high acquisition costs, the right softening plant offers a good amortization due to this longevity and due to the various saving potentials.

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