Types of water filters

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Updated on: 03/26/2020

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Filter systems and methods

Basically, water filters are devices designed to improve the quality of drinking water, i.e. to remove or reduce the concentration of impurities such as particles, turbidity and microorganisms, pathogens or substances dissolved in water. There are water filter types based on different processes and each manufacturer will recommend the advantages of his own process to interested parties.

Water filters can be differentiated between purely physical, mechanically working filters, which, simply put, remove impurities from drinking water like a sieve, and those that can remove dissolved substances by means of chemical-physical effects.

The first group includes sand, gravel, plastic or metal filters as well as ultra- and microfiltration systems. By means of a sieve effect they remove all solid substances from drinking water that are too large to pass through the filter medium. Substances dissolved in water, on the other hand, cannot be filtered out.

Such dissolved substances, however, are removed by means of chemical-physical filter media, e.g. organic substances by adsorption with activated carbon or by ion exchange with appropriate ion exchange materials or calcium or magnesium cations.

Diffusion membranes of nanofiltration or reverse osmosis take a special position: They can be used to remove both dissolved organic substances and dissolved salts (ions) from drinking water.

Drinking water filters according to application

There is a wide range of drinking water filters on offer, which can be divided into three categories according to where they are used:

-Home inlet filters - Water filter systems for installation at the water inlet point in the cellar
-endpoint filter- built-in filter at the tapping point under the sink or directly at the tap/shower hose (Alb filter)
-Table can filter Tischkannenfilter

House entrance filter

House inlet filters in the main water pipe protect the water pipes in the building from dirt and particles that enter the house water pipes from the public drinking water network. They are known as coarse filters or sediment filters (usually with a fineness of 100 µm) and are even legally required for new buildings with metallic pipes. However, house entrance filters are not comparable with fine filters.

Can Filter

Most people understand the term water filter to mean a conventional table pot filter such as those made by Brita. The filter cartridges usually contain loose activated carbon granules, which bind e.g. chlorine and organic impurities and remove unpleasant taste and smell. Models with an ion exchanger made of plastic resin also reduce the water hardness, i.e. they also bind lime (calcium and magnesium) with restrictions. The primary aim of table-top can filters is to remove unpleasant tastes, odours and water hardness, so that tea or other hot drinks taste better, for example. However, since jug filters cannot remove harmful substances, the term water filter is actually misleading in this context. 

Can filters have a strong tendency to microbial contamination, especially if the filter is not used for a longer period of time or the water is at room temperature in the container, germs can multiply quickly. For this reason, the activated carbon granulate is often mixed with disinfectants (such as silver compounds), but these are also released back into the water in small quantities.
Furthermore, the absorption capacity of the activated carbon granulate of a cartridge is limited and exhausted after about 100-150 litres. If the filter cartridge is not changed in time, the previously bound pollutants can be dissolved again and released into the water in concentrated form. This is called bleeding or breakthrough of the filter.

tap filter

Built-in filters, which are installed directly at the tapping point under the sink or directly at the tap in the kitchen or before the shower hose in the bathroom (i.e. those offered by Alb Filter), filter the water at the tapping point directly before consumption. There are appliances that are placed on the kitchen worktop (tabletop filters) or more elegant solutions for installation under the sink (built-in filters), and finally those that allow the extraction of filtered or unfiltered drinking water directly from the tap.
Depending on the requirements, the cartridges contain different filter materials, from activated carbon granules to activated carbon monoblock filters and elaborate hollow fibre membranes for ultrafiltration, which reliably protect against legionella and dangerous microorganisms in shower and drinking water.

Mobile filters

A subheading includes travel and outdoor models for on the move. Outdoor and camping friends
often face the problem of not always having fresh and germ-free water available.
For this reason there are now travel and outdoor filters that are compact and easy to use. They can be mounted directly on the tap and contain activated carbon cartridges that clean ominous tap water or even sea, river and rain water not only of visible dirt particles but also of pollutants such as bacteria, microorganisms, viruses and toxic heavy metals.