There are over 19 million residential buildings in Germany (1). They are supplied with high water quality in accordance with the Drinking Water Ordinance, which is regularly checked by the local drinking water supplier. Overall, German drinking water is among the best in the world. However, drinking water is hard in around 40 percent of all households (2).
Hard tap water contains a lot lime, but also a particularly high amount of the valuable minerals calcium and magnesium. It is therefore similar to high-quality mineral water that we can buy at the supermarket. But these minerals, which are important for the human organism, have a negative effect on a building's drinking water installation in the long term. Almost everyone can see this in the household on a daily basis: pipes, fittings, surfaces, washing machines and household appliances calcify when high degree of hardness particularly fast.
While we household appliances and can usually remove stubborn calcium deposits from surfaces themselves by descaling or intensive cleaning, the situation is different when it comes to technical building installations: Existing layers of lime in pipes or hot water generation systems (e.g. in boilers or instantaneous water heaters) can only be removed by specialist companies in the HVAC sector. On the one hand, these experts can remove the calcifications in a complex manner using appropriate tools and chemicals. On the other hand, after a certain period of time and in the case of advanced calcification, only the replacement or replacement of certain components of the drinking water installation can help. This removal of the deposits is then particularly cost-intensive.
Descaling systems, also known as softening or soft water systems, prevent exactly such problems in the long term. They reduce maintenance and follow-up costs for a building's drinking water installation, have a positive effect on drinking water hygiene in a pipeline network and at the same time prevent loss of energy efficiency. This is because every millimetre of lime layer increases energy consumption and therefore CO2 emissions when producing warm water. A descaling system is therefore not just a convenient issue that makes cleaning and descaling processes easier. With the right descaling system, a building becomes more climate-friendly.
In England, the “Domestic Heating Compliance Guide” published by the British Deputy Prime Minister therefore requires that a descaling system be installed in new buildings in regions with hard drinking water (3).
Yes, calcium deposits are annoying. However, installing a descaling system is not always recommended for technical reasons. Depending on the model and process, the systems can be expensive. A soft water system for a single-family home can cost up to 3,000 euros.
For this reason, the German Gas and Water Association (DVGW e.V.) only recommends the use of a descaling system when a household is supplied with hard drinking water. Speaking in figures: The total water hardness is 14°dH (degree of German hardness) or more (4). Therefore, the first step before considering purchasing a descaling system should be to determine the water hardness.
In Germany, you can independently find out how calcareous your water is in just a few minutes.
Here you can determine the Water hardness for your region
Will the total water hardness Indicated by the local drinking water supplier or by its own water hardness test of more than 14°dH, it is classified as “hard”. Here, a descaling system is technically recommended to prevent increased calcium formation on surfaces. If your water hardness is below 14°dH total water hardness, you can still opt for a descaling system. In this case, however, this is done more for reasons of comfort.
There are numerous providers of water decalcification systems on the Internet, Softening systems and Soft water systems. What is little known, however, is that the term descaling plant is not protected. This is why it covers a wide range of different products and systems.
The term “descaling plant” leaves a lot of room for interpretation. It is composed of the words “decalcification” and “plant.” In the home environment, the term “decalcification” is understood to mean the removal or removal of existing deposits of lime. This means that decalcifications are often used at home on kitchen appliances such as coffee makers and kettles carried out.
There is also decalcification of the drinking water installation, such as Boiler decalcification or decalcification of drinking water pipes. These too should be freed from existing calcium deposits. Descaling is carried out by manual work (e.g. by brushing or scraping) and with the aid of cleaning or descaling agents (e.g. vinegar essence or citric acid).
There is no system that independently removes existing calcium deposits, i.e. decalcifies. The term “descaling plant” can therefore quickly be misunderstood. The purpose of these plants is not to remove calcium deposits. Instead, the aim is to prevent calcium deposits from forming.
Experts understand “descaling plant” as a collective term for technologies and products that prevent or reduce problems caused by calcium deposits due to hard water.
The terms water softening or soft water plant are often used as a synonym for the word descaling plant. The concept of water softening narrows down various methods for treating water against lime in more detail. While some processes reduce water hardness, the water hardness or lime content of others remain largely unchanged.
In popular specialist reading such as “Baustofflehre — Bau und Energie. Practical guide” by Gustav Peter, Marc Ladner and René Muntwyler (5) or “Home Technology: Basics - Planning - Execution” by Thomas and Erhard Laasch (6), a distinction is made between water-softening and non-water-softening forms of lime control.
One of the most important measures to reduce water hardness is ion exchange. In contrast, the amount of lime in water remains unchanged, e.g. with the electrophysical method, water softening by phosphate dosing and physical water softening.
When looking for the right descaling system, it is therefore important whether it is a product that reduces water hardness or a system that leaves the amount of lime in the water unchanged but still prevents calcium deposits. Two methods that are frequently used in Germany are explained below.
In building technology, so-called ion exchangers are one of the most frequently used technologies for softening calcareous water and preventing calcium deposits. The lime in the water, which is composed of calcium and magnesium, is replaced by sodium through the use of tablets. This exchange with sodium ions reduces water hardness so that households have to deal with less calcium deposits.
For these reasons, California, for example, has the so-called “water softener ban”, which was signed by Governor Arnold Schwarzenegger in 2006 (8, 9). According to this law, the installation of water softening systems is prohibited in certain regions.
Read more about the Disadvantages of water softening systems with ion exchange.
So-called lime protection systems are an effective alternative to descaling systems with ion exchangers. These reduce calcium deposits without the use of sodium chloride. Lime protection systems work according to the principle of so-called seed crystal formation.
Read more about Lime protection systems.
In principle, it is difficult to say whether a descaling system with ion exchangers or a lime protection system based on the principle of seed crystal formation provides a better result in a household. Both types of processes reduce calcium deposits.
Since lime protection systems leave the lime content unchanged, calcium deposits may remain visible on a surface when water evaporates. On the other hand, even descaling systems with ion exchangers do not completely remove the lime from drinking water. As a rule, this process always leaves a residual water hardness in the drinking water so that the water does not have a corrosive effect or the sodium value rises too much.
Both systems therefore mean that cleaning and lime never have to be removed from surfaces again. However, both systems make life easier with lime in your own home. When making a purchase, it also depends on your preferences in terms of environmental friendliness and drinking water quality.
Both types of processes, both descaling systems with ion exchangers and lime protection systems, are usually installed as a complete building solution at the house water connection behind the water flow meter (water meter) of a building. Depending on the process, the following requirements may be required:
The operating costs of a descaling plant with ion exchangers differ from that of a lime protection plant. It is therefore advisable to ask the respective manufacturer or provider already during the offer phase which tasks and Consequential costs when operating a descaling plant arise.
Due to the large number of descaling systems, it is recommended to compare different offers before purchasing. Offers can be obtained both from the local installer you trust and on the Internet. Online in particular, there are now also providers who, in addition to the descaling system, also offer an installation service from specialist companies in the HVAC sector.
As soon as you have various offers, a structured comparison of offers helps to identify the best descaling system for you.
Some offers quote a common flat rate for the descaling system and installation. Since this offers little transparency, the device price and installation costs should always be requested separately.
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An alternative to the classic descaling system is AQON PURE lime protection system. In accordance with the principle of seed crystal formation, it reduces calcium deposits in drinking water installations without removing the minerals calcium and magnesium from the drinking water. AQON PURE is also maintenance-free and, depending on the model, has a useful life of up to 20 years.
Up and running: Get the offer in just 2 minutes - optional with installation at a fixed price.
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(1) Federal Statistical Office: Inventory of apartments and residential buildings. Completion of construction of apartments and residential buildings. Long series from 1969 — 2020 (2021)
(2) Schodorf, Willibald: Water treatment using traditional methods: Focus on efficiency brake lime, 2012, in: SBZ Sanitär. heater. Climate, issue 13 (2012)
(3) Office of the Deputy Prime Minister (United Kingdom), Domestic Heating Compliance Guide (2006)
(4) German Gas and Water Association e.V. (DVGW): Water treatment in drinking water installations, in: twin No. 07 (2013)
(5) Gustav Peter, Marc Ladner, René Muntwyler; Building Materials Theory — Construction and Energy. Practical guide”, Springer-Verlag (2013)
(6) Thomas Laasch, Erhard Laasch; “Home Technology: Basics - Planning - Execution”, Springer-Verlag (2012)
(7) Bavarian State Office for the Environment: Decentralized Softening, as of January 29, 2008
(8) California Legislative Information. Senate Bill No. 475, CHAPTER 393: Drinking Water: Residential Self-Regenerating Water Softeners: Santa Clara River: leginfo.legislature.ca.gov/faces/BillTextClient.xhtml. Retrieved on 12/10/2020
(9) Los Angeles County Sanitation Districts. Governor Signs Bill Empowering Santa Clarita Valley Sanitation District to Offer and Promote Enhanced Rebate Program: www.lacsd.org/news/displaynews.asp. Retrieved on 12/10/2020
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