The headlines were enough to make you anxious. “Water filters tested: More germs than before”, “Water filters quickly become breeding grounds for germs” or “Water filters: No protection against Legionella”. The statements in the following articles continue where the headlines left off. It is reported that water filters are pointless because drinking water in Germany is flawless. “There hasn’t been a single case of illness caused by water from waterworks for decades,” explains Professor Franz Daschner, former director of the Institute for Environmental Medicine and Hospital Hygiene at the University Hospital Freiburg, to Apotheken-Umschau.
Legionella, which are often warned about, usually only enter the tap water inside the house anyway, and a water filter does not protect against Legionella, the article conveys to the reader. T-Online speaks of the good quality of German drinking water and explains that “a water filter does not improve it. Rather, they often cause the water to be unnecessarily contaminated with germs and pollutants.” Furthermore, reference is made to the Consumer Protection Centre of North Rhine-Westphalia, which describes water filters as mostly “an unnecessary investment.” The NDR also caused a media stir with its test of four different water filters.
The problem with this type of reporting is the misleading of readers, whether intentional or unintentional. The topic of water filters was not reported on in enough detail or with sufficient differentiation. However, one-sided and opinion-shaping reporting seems to be part of the standard tone of media coverage today. Topics apparently have to be sensational and shocking to capture the reader’s attention. The fact remains that not all filtration systems are “breeding grounds for germs” and that many consumers have legitimate reasons to further treat their drinking water through filtration.
The most likely cause is the proliferation of germs on the moist activated carbon, where they can settle on the surface. A moist environment is ideal for germs to multiply. The tabletop filters from BWT and BRITA also released silver into the water. The heavy metal is added to the filters to kill germs. However, there are germs that are not killed by silver ions. In the BWT tabletop filter, the silver apparently had no effect and additionally contaminated the water. Except for the Samsung cartridge, all filters had an indicator showing when the filter should be changed, although depending on the fridge where the filter is installed, an indicator is present. Apparently, however, these indicators react too late.
The water filter test by NDR roughly reflects the results of the research by Professor Franz Daschner. Professor Daschner was also able to demonstrate that germs grow on many water filters. However, this exclusively concerned water filtration with activated carbon and not water filters in general. Some manufacturers reacted to the results and impregnated their activated carbon with silver ions. This had no effect on silver-resistant germs and, moreover, silver ions entered the filtered water. The sensationalist media claim that water filters are germ incubators is not sustainable at all. It exclusively concerns water filters with activated carbon filtration.
Furthermore, alongside the generalised negative statement about water filters, persistent reports were made about the futility of water filters. Water filters are said to be completely pointless and downright unnecessary. After all, German drinking water is the best controlled foodstuff, and waterworks continuously monitor and control the drinking water. The truth is that water utilities continuously monitor about 49 chemical and microbiological parameters of the Drinking Water Ordinance and their legally prescribed limit values. The increasing pollution of surface waters and groundwater reservoirs by agriculture, industry and population growth with pharmaceuticals, fertilisers, pesticides, a variety of chemical substances, microplastics, hormones and many other contaminants is making it increasingly difficult for water utilities to treat drinking water. Germany is criticised by the EU for its excessively nitrate-rich soils, and the EU demands measures to ensure compliance with the limit values, which are constantly exceeded. The problem of pharmaceuticals and their degradation products in German waters is growing rather than being solved.
Even bottled water is no guarantee of a harmless product, as repeatedly shown by tests from consumer protection organisations such as Ökotest, Stiftung Warentest or various consumer protection TV formats. In Ökotest's test of 75 mineral waters, pesticide metabolites were found in every fifth mineral water. Some brands contained too much boron and uranium. In a Stiftung Warentest investigation, more than one in three still waters showed germs. Regarding the alleged "original purity" of mineral water, according to the final ruling of the Administrative Court of Baden-Württemberg, degradation products of plant protection products may be present. "A revocation of a state recognition as 'natural mineral water' due to existing, but harmless to human health, contamination by degradation products (metabolites) of plant protection products cannot be based on the requirement of 'original purity' in the Mineral and Table Water Ordinance (MTVO) that absolutely no pollutants may be present, because only a normative purity is required. The boundary between recognisable and non-recognisable mineral water in terms of contamination must be laid down in the ordinance itself due to its effects on professional freedom. An internal administrative regulation's 'orientation value' for pesticides and pharmaceuticals of 0.05 µg/l does not replace the required normative regulation," states the reasoning in the ruling.
So if it cannot be ruled out that neither mineral or bottled water nor tap water is contaminated with germs and/or other potentially harmful substances, how can it then be claimed that water filters for domestic use are pointless and useless? There are proven systems for water treatment and filtration that reliably and demonstrably filter out germs and other contaminants. High-quality molecular filter reverse osmosis systems produce pure water and reliably filter out all microbiological and chemical substances by more than 95 percent.
The Consumer Advice Centre of North Rhine-Westphalia lists on its website on the topic "Water filters and softeners in the household: mostly a superfluous investment" the various systems for water filtration with their respective advantages and disadvantages.
Of course, membrane reverse osmosis technology is also mentioned. The listed disadvantages relate to possible contamination and the high water and energy consumption, because "to prevent the fine membrane from clogging, it must be flushed with high water consumption. To obtain 1 litre of filtered water, for example, 3 litres of drinking water are needed. The consequence: high energy and water costs. The membrane is susceptible to contamination because suspended solids accumulate there. Long-term consumption of this water can deplete the body of minerals and lead to deficiencies."
This statement contains a contradiction and lacks an explanation as to why the membrane is supposed to be susceptible to contamination. It is contradictory that if the membrane is flushed under "high water consumption", how it could then become contaminated. Other statements are also outdated. Good molecular filter reverse osmosis systems nowadays have a ratio of pure water (permeate) to wastewater (concentrate) of 1 to 1, i.e. for one litre of pure water, one litre of water is discharged into the drain. In addition, good molecular filter reverse osmosis systems have an automatic flushing system that flushes the membrane from the inside as well as the outside for cleaning before each water withdrawal. Energy costs are low because a molecular filter reverse osmosis system for domestic use does not run continuously but only produces water when needed.
The still cited disadvantage of mineral deficiency or mineral depletion of the body is scientifically untenable. Rather, it is becoming increasingly clear medically and scientifically that the purer the drinking water, the better it can fulfil its functions in the body. It is also not the task of water to supply the body with minerals. Nutrition takes care of that. Mineral waters are also not the important source for mineral requirements as is often suggested. Only a few mineral waters contain more than 1,500 milligrams of minerals per litre. Often a mineral water stands out with a single mineral in a higher dose. One mineral water may have particularly high calcium, another much magnesium, and the next a lot of potassium. According to Stiftung Warentest, about half of all classic waters (carbonated mineral water) are low in minerals. Among still waters, even more than two thirds contain less than 500 milligrams of minerals. The alleged disadvantages of molecular filter reverse osmosis systems as presented by the Consumer Advice Centre of North Rhine-Westphalia are neither conclusive nor valid as justification. However, the Consumer Advice Centre of North Rhine-Westphalia is correct in one respect. It explains for whom molecular filter reverse osmosis systems are useful, because this process "also produces 'ultrapure water' for laboratories and space travel." And in space travel and laboratories, certainly no water filters are used that are "germ incubators."