Last updated: August 11, 2021
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Water purifiers offer a simple and quick way to purify water. One often hears reports of bad water spoiling the stomach. Especially when travelling, this happens more often. But whether chlorine, limescale, bacteria or germs, the right water purifier filters them all and protects your health.

Of course, there are different types of water purifiers. In our water purifier test 2022 we compare water purifiers for outdoor, indoor or aquarium use with their advantages and disadvantages. We also show you some alternatives. Of course, we can't make the decision for you, but we try to make it easier for you.


  • A water purifier is a device that filters water by using various processes. Thus, stocks of heavy metals, lime or chlorine can be easily filtered out. It also rids water from streams or rivers of many germs and bacteria.
  • There are many different applications for water purifiers. You can filter your drinking water, free your aquarium from substances that are harmful to fish, or keep your pond or pool cleaner.
  • The difference in filter performance between the various devices is enormous. Here it is important to familiarise yourself sufficiently with the product. You should not buy the cheapest product directly, as it may be that the filter performance suffers from the low price.

The Best Water Purifier: Our Picks

Water purifier: purchase and evaluation criteria

When it comes to buying a water conditioner, you should of course first consider which criteria you find relevant for the purchase. This depends on the purpose for which you want to buy the water conditioner.

In the following, we will explain the individual criteria in more detail. Here we will look at the water conditioners for drinking water and aquariums.

Filter performance

The filter performance is without a doubt the most elementary purchase criterion of a water conditioner. After all, why buy a water conditioner that does not filter?

Different water conditioners naturally filter different substances out of the water. Each water purifier advertises the best filtering performance. Whether these figures are always correct is questionable.

Before buying a water conditioner, you should study its filtering performance thoroughly and not just listen to the manufacturer's claims.

Water conditioners for aquariums or ponds aim to filter the water in such a way that substances that could be harmful to fish in it are filtered out. This usually involves filtering out heavy metals such as lead or zinc. Chlorine is also filtered out. This can be fatal for fish in certain quantities.

Water purifiers for drinking water, on the other hand, should filter out harmful substances for us humans. This is often done with spring water from nature. Viruses, bacteria, germs or other harmful substances should be filtered out. If the water purifier has a certain filtering capacity, the water can then be drunk without hesitation.

To drink tap water in Germany, a water purifier is usually not necessary. German tap water is very closely monitored, so you can drink it without worrying.

Shelf life

Different water purifiers have different shelf lives. A water purifier usually has a maximum amount of water that it can filter. After that, the filter for drinking water usually has to be replaced.

For aquariums, of course, the question is how long a water conditioner will last before you have to add it again. The less often you have to use it, the better for the fish living in it.

The shelf life of the product itself goes hand in hand with the criterion of the quantity to be bought. If it has a long shelf life, you can buy more without hesitation.

If it has a short shelf life, there is a risk that it may be harmful to the animals after the expiry date has been reached.

Quantities and sizes

Water conditioners for drinking water come in different sizes. For outdoor use, these are usually small and handy. Indoors, the sizes range from a small water filter to a large water purifier.

When hiking, water can be very annoying because of its weight. A small water filter that can make water from nature drinkable is of course a welcome relief here. This way you don't have to worry about the water supply if there are enough springs on your way.

Water conditioners for aquariums are usually a powder or liquid that can be bought in various quantities. Quantities range from 15 millilitres to 5 litres.

Ease of use

The simplicity of use is mainly relevant for aquariums and ponds, as incorrect use can cause enormous damage to the environment. If it is not used exactly as instructed, this can already lead to the death of some creatures.

You should always work according to the instructions provided and follow all directions. Otherwise the product can become a danger to the fish.

Water filters for drinking water are usually relatively similar in their application. Systems for water treatment naturally require a certain amount of effort to install. However, smaller models can usually be used without much difficulty.

Water purifiers: frequently asked questions and answers

In the following section we would like to answer frequently asked questions about water purifiers. The answers refer to water purifiers for drinking water.

What is a water conditioner?

A water conditioner is basically a product that reduces or changes some of the components or properties contained in water. The aim is to improve the quality of the water.

The more often you filter water, the cleaner it becomes. (Image source: Baudolino /

These changes to water are used both in private households and in commercial facilities, such as sewage treatment plants. In the process, tap water or water from nature can be filtered so that it can be drunk without any problems.

Many people think that a water purifier is just a way to filter water. However, water purifiers are also used in other applications. For example, a water bubbler that adds carbon dioxide to tap water is also a water purifier, although the water is not filtered.

For whom is a water purifier suitable?

Basically, a water purifier is suitable for everyone. Due to the promised filter performance, there are now some households that own such a water filter.

Calcification can even destroy kitchen appliances. A water purifier helps to prevent this.

In Germany, very hard water, i.e. water containing limescale, sometimes comes out of the tap. A water conditioner can be used to soften the water. However, tap water is generally drinkable throughout Germany. So a water conditioner is not absolutely necessary. However, if limescale stains or the like bother you, a water purifier can help.

The situation is different with water from nature. This often contains bacteria and germs. A small outdoor water purifier can help here. In addition, you don't have to carry many unnecessary kilos of water on your back. You can simply filter spring water or water from rivers and drink it. The small water filters are also suitable for travelling.

An outdoor water purifier is perfect for filtering water from nature. This way, you can drink water from streams or rivers without worrying. (Image source: MooreProtectionVienna /

Some people also prefer to drink sparkling water instead of still water. For this purpose, there are also water purifiers that freshen up tap water with carbonic acid. This means you don't have to buy sparkling water.

What types of water purifiers are there?

When buying a water purifier, you first need to be aware of the different types. You have already learned about some of them in this article. The following table lists all types with their advantages and disadvantages:

Type Advantages Disadvantages
Water purifier for drinking water Filters heavy metals such as zinc or copper, but also viruses, bacteria and germs, so that you can drink water without worrying The filter performance is questionable with some devices. You can use our test to find out which water purifiers are suitable
Water purifiers for aquariums and ponds filter substances that are harmful to fish out of the water and protect their mucous membranes if used incorrectly, the water purifier can cause more damage than it prevents
Water purification systems usually filter the water much more effectively and ensure filtered water before it comes out of the tap installation usually involves more effort or costs

Water purifiers for drinking water are also classified for indoor or outdoor use. Outdoor water purifiers are usually very small and compact so that you can easily carry them with you.

In addition, water purifiers are available in all possible forms. For example, as a liquid or tablets that are added to a water tank, or simply as a solid filter into which water is emptied.

How much does a water purifier cost?

The prices for water filters for drinking water have a wide range. The price varies depending on the size and filter capacity. The price range here goes from about 10 to 3000 euros. The upper price range seems extremely expensive at first, but the filter performance cannot be compared with cheaper variants.

The filter performance should always be more important than the price.

A small, handy water filter starts at a price of 10 euros. These are usually made of plastic. In addition, the type of filter is usually not very complex, which explains the low price.

The better the filter performance, the more expensive the water purifier. Small household devices will usually not cost more than 500 euros. However, fixed systems for filtering water, for example decalcification systems, can cost up to 3000 euros. Given the filtering capacity and complexity of such a system, this price is usually justified.

Type price range
Water purifiers for drinking water approx. 10-200 euros
Water purifiers for aquariums and ponds approx. 5-50 euros per litre
Water purifiers approx. 50-3000 euros, depending on size

The price ranges are of course very wide. Unfortunately, this is also due to the different brands that offer the products. Systems costing more than 1000 euros are usually intended for commercial use and not for private households.

What alternatives are there to a water purifier?

Of course, there are also some alternatives to purify your water. We would like to explain them to you in more detail in the following table:

Alternative Description
Boil water To rid water of bacteria and germs, you can simply boil it, i.e. heat it to 100 degrees. This kills them. In addition, lime is lost.
UV light It is also possible to remove bacteria and viruses from water with the help of UV light. To do this, however, you need a UV lamp, which you usually don't have in your pocket.
Tablets As mentioned in the article, there are also tablets that can remove harmful substances from water. These are often used by the German armed forces.

You must decide for yourself whether these alternatives are an option for you. However, it is generally easier to use a water purifier that does the work for you.

Boiling water has always been an alternative to remove bacteria and germs from water. (Image source: Dimitri Houtteman /

The disadvantage of using tablets to treat water is that these tablets often change the taste and smell of the water. Thus, for many users, the disinfected water turns out to be undrinkable afterwards.

How does a water purifier work?

Basically, there are five different ways to purify water. We have briefly listed and explained these five here:

  • Mechanical treatment: Mechanical treatment is the mechanical purification of water. The methods for this are quite conventional, as everyone knows them. These include methods such as sieving, filtering or raking.
  • Physical methods: Here, the water is purified on a physical basis. Methods here are, for example, a vacuum process or thermal effects, such as heating the water.
  • Chemical processes: Here, water is purified by chemical reactions. Known examples are disinfection or oxidation.
  • Membrane process: The membrane process is based on the separation of substances by means of membranes. Water purifiers often use reverse osmosis. An osmosis system for purifying water presses tap water through an osmosis membrane. This membrane only allows pure water molecules to pass through. The resulting osmosis water is therefore water that no longer contains any other substances.
  • Biological processes: Biological processes are less important in the treatment of drinking water. Examples of these are sludge digestion and biochemical oxidation.

These processes can all be used for the treatment of water. In water filtration systems, the membrane process is often used. Smaller household appliances usually have several filter stages. These include mechanical filters, but also physical filters such as adsorption with activated carbon.

How do I use a water purifier?

There are different approaches to water purifiers for drinking water. An outdoor water filter is usually based on pressure. Water is pumped from a stream, for example, and forced through a filter. The end result is filtered water.

Many household water purifiers are easy to fill. They consist of a jug and a filter lid. The filter lid sits on top of the jug. To filter, you fill water into the filter from above. The filtered water then ends up directly in the jug.

A water treatment system is somewhat more complex. It usually has to be connected to the household water system. All the water used in the house is thus already filtered before it leaves the tap.


No matter what you need it for, a water purifier can make many things easier in everyday life. Be it the infrequent descaling of coffee machines, or drinking water in the great outdoors. Unlike other ways to purify water, such as with UV light, a water purifier offers a quick, hassle-free and efficient result.

While water purifiers provide very clean and pure water, but require a certain amount of effort before use, smaller water purifiers usually filter a little less, but are very easy to use. We hope that our test has helped you with your purchase decision.

Picture source: Hidalgo/