Contamination in the water filter?

Time and again you come across the - far too generalized - statement that water filters are germ slingers. However, anyone who takes a closer look and examines the properties and modes of action of the various water filters knows that bacteria or germs form to varying degrees in all water filters.

The most common technologies and types of water filters and filtration processes include

• Activated carbon block filter
• Reverse osmosis filter
• Ion exchanger
• UV disinfection
• Distillation process
• Table filter & jug filter

Jug or table water filters are particularly widespread, but it is precisely with these products that extra caution is required, because the supposedly filtered water from jug filters actually tends to quickly become contaminated.

Therefore, almost all reports about the risk of contamination with water filters refer to table filters and jug filters. However, they certainly do not refer to activated carbon block filters , as these can also be built to be germ-proof.

However, each filtration process has its own characteristics with regard to bacteria and germs. In this article, you will find out in detail which processes require special care in terms of contamination and what distinguishes the techniques from one another. Guidebook .

Risk of contamination with jug or table water filters

Jug or table water filters are probably the best-known form of "water filter" in Germany. They are filled with loose activated carbon granulate and, depending on the model, also contain ion exchangers or beads made of plastic resin. Their performance is limited to the ...

• ... removal or reduction of limescale, 
• ... conversion of certain pollutants (by ion exchange),
• ... reduction of chlorine,
• ... and the removal of taste- or odor-impairing substances (through the loose activated carbon granulate). 

What do jug or table filters do?

The purpose of a table water filter is primarily to improve the taste or decalcify tap water. For example, to improve the quality of hot drinks such as tea or coffee. 

Targeted filtering in the sense of removing impurities such as ...

• Pesticides
• Germs & bacteria
• Heavy metals
• Hormones
• Drug residues
• or nitrates

... hardly takes place with jug or table water filters.

The term 'water filter' is therefore somewhat misleading in this context. All the more so because, in contrast to other filtration methods, the risk of contamination is particularly high with table filters. 

Risk factors: Room temperature & activated carbon granulate

Jug filters have a strong tendency to become contaminated, especially in summer or at hot temperatures. If the table water filter has not been used for a long time or the water is left in the jug at room temperature, the germs in the water can multiply rapidly. 

For this reason, the loose activated carbon granulate with which the filter cartridges of jug filters are usually filled is often mixed with disinfectants such as silver compounds. Unfortunately, these can also be released into the drinking water in small quantities. So far there is little knowledge about the effects of silver ions on the human organism. 

Can filters are not subject to the Drinking Water Ordinance

In addition, Tapwater treated with jug filters is not subject to the strict German Drinking Water Ordinance , but to the more lax Food and Consumer Goods Ordinance (LMBG). Therefore, the treated water may have a much higher germ count than is permitted under the German Drinking Water Ordinance for Tapwater is allowed. ^[1]

Risk of contamination with other filter methods?

However, caution is also required with other common filtration processes. This is because with ion exchangers as well as reverse osmosis and distillation processes, the techniques can lead to a proliferation of germs or bacteria in the drinking water. bacteria in drinking water in drinking water. It is therefore important to understand their mechanisms of action in detail.

Contamination with ion exchange filters?

Ion exchange filters are designed in such a way that they can primarily convert limescale and some pollutants such as nitrates by ion exchange - for example, by removing lead ions, copper ions or calcium ions.

It works something like this:

• Ions are nothing more than electrically charged atoms or molecules.
• An ion exchange filter makes use of these electromagnetic forces to remove certain substances (atoms) from the drinking water.
• The principle of operation is that the unwanted ion, i.e. the substance to be removed from the water, is bound to the ion contained in the ion exchanger.
• However, the ion exchanger material can only ever exchange certain substances.
• A cation ion exchanger replaces calcium cations, i.e. lime, which is found in Tapwater occurs. (Cation exchangers are found in dishwashers, for example.)
• At some point, the ion exchanger is exhausted and completely saturated (e.g. with calcium cations). It must then be regenerated or recharged, otherwise it will release the exchanged ions back into the water.

The filter medium itself is usually made of synthetic resins. Germs and bacteria can easily multiply on this if the devices are not used for a long time or if the water stands for a long time.

Another pain point is the environmental balance: the filter cartridges are not recyclable, cause an unnecessary amount of waste and the devices consume a lot of energy.

Contamination in reverse osmosis processes

Reverse osmosis is a physical water treatment process that can be used to make even the dirtiest water drinkable again.

The process works something like this:

• The water is pressed through a kind of "sieve".
• The sieve has such small pores that only water molecules can pass through.
• This is ensured by a semi-permeable osmosis membrane, which prevents the purified water from flowing back again.
• In this way, clean water is obtained from contaminated water.

However, the reverse osmosis process not only retains undesirable substances (e.g. nitrates, phosphates, hormones, bacteria or heavy metals), but also desirable nutrients or minerals such as calcium or magnesium. This means that the "ultra-pure water" may not be as healthy as the consumer hopes. In addition, high energy and water costs are also to be expected with this process.

Contamination during distillation?

Steam distillation can be used to remove unwanted substances such as drug residues, hormones, microplastics and heavy metals from the water.

The procedure is as follows:

• The drinking water is boiled.
• The water evaporates and rises to the top.
• The pollutants stick to the ground.
• Once at the top, the steam condenses and cools down again.
• The condensed water can drip off in an external container.

In principle, the process is reliable. It should only be noted that harmful substances with a boiling point higher than 100 degrees Celsius remain behind, as do valuable minerals. However, as this is the case with very few bacteria, the risk of contamination is actually low.

Contamination in activated carbon block filters

What is annoying in this context is that consumer protection organizations or press portals such as the Stern never tire of writing about the risk of contamination with activated carbon filters, but do not differentiate at all in this respect. ^[4] The fact is:

While a table-top jug filter can only improve the smell and taste of the water with its loose activated carbon granulate, an activated carbon block filter cleans the water much more thoroughly of all kinds of pollutants - using three different mechanisms of action.

Three mechanisms of action of the activated carbon block filter briefly explained:

1. Mechanical effect:
Mechanical filtration works via the many fine channels of the activated carbon block, which prevent too large particles from passing through the activated carbon filter (e.g. sand, rust, asbestos fibers, bacteria, etc.)

2. Catalytic effect:
The catalytic principle causes small particles to be converted through the finely arranged pores - e.g. chlorine.

3. adsorptive effect:
The adsorptive effect of activated carbon filters is similar to that of a strong magnet. Substances that are adsorbed include odor- and taste-impairing substances, heavy metals (e.g. lead, copper), residues of hormones, medicines and much more. (Van der Waals forces)

Activated charcoal block filters are NOT table filters

This means that the performance spectrum of an activated carbon block filter (see table) is significantly greater than that of a table or jug filter. It therefore makes little sense to lump both water filters together and refer to them as "activated carbon filters".

To put it bluntly, it is a comparison of apples and oranges!

Substances that activated carbon block filters can filter

Better bottled water instead Tapwater ?

Anyone who is wondering whether they should not just buy bottled water to be on the safe side is wrong. In 2016, Stiftung Warentest came to the conclusion that Tapwater is healthier than mineral water.

The claim that “ mineral water contains more minerals ” turns out to be a myth . On the contrary, Tapwater often contains more minerals and fewer unhealthy residues. Water in plastic bottles can also be contaminated. ^[5]

As we have shown in other guides , worrying concentrations of substances such as

• hormones,
• Microplastics,
• Bacteria & germs,
• and much more.

Da Tapwater is one of the most strictly controlled foods in Germany, and is examined much more closely than commercially available mineral water.

Statement by Stiftung Warentest

"Water suppliers must test their water regularly. In terms of germs, this applies to large companies several times a day. This makes it the most strictly controlled foodstuff in Germany. [...] There are significantly more regulations for tap water than for mineral water: for example, limits for pesticides and uranium." ^[6]

Good water filters are a valuable investment

Are water filters a “superfluous investment” ? Since numerous dangers are caused by ingredients and bacteria from the Tapwater We take the position: filter water beats Tapwater .

This is particularly true because not all water filters are breeding grounds for germs . The risk of contamination is particularly high with jug and table water filters, but nowhere near as high as with drinking water filters made from high-quality, sintered activated carbon blocks .

With good water filters, you just need to remember that the filter cartridges need to be changed regularly . Not to prevent contamination, but to maintain the filter performance permanently and at a constant level.

Questions and answers

How dangerous are water filters?

Alb Filter water filters are absolutely safe. Such reports - which are usually based on an article in Stern - refer exclusively to table water filters, which have little or nothing in common with our permanently installed water filter systems. With table water filters, there is a particular risk of high levels of contamination if the filter medium is not changed in good time.

What substances do water filters filter?

Good water filters - e.g. activated carbon block filters - are versatile: they can filter microplastics, hormones or medicines (residues) just as effectively as copper or lead. Activated carbon block filters (depending on porosity) are also well suited to removing bacteria, germs (e.g. e-coli) and legionella from drinking water. legionella or simply to remove unpleasant tastes and odors.

What are the benefits of a water filter?

Our Tapwater in Germany is strictly controlled, but the reality sometimes shows serious deficiencies. Some substance concentrations such as drug, hormone, microplastic or pesticide residues are not officially listed in the Drinking Water Ordinance !

How long can you use water filters?

In Alb filters, the cartridges consist of a specially sintered core of activated carbon (Active) or bioclay (Active Plus), which loses its filter performance over time. We recommend changing the cartridge after a maximum of 4 months - depending on how the cartridge is used.

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