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Lisa Scholl

Lisa Scholl


Build your own water filter – step by step instructions

The water that comes out of the tap in Germany must meet high quality standards and is therefore generally safe to drink. But despite the strict controls, there are many reasons to additionally filter the water before consumption. Especially when traveling or in nature, it is necessary to thoroughly clean and purify water before drinking. Water filters are available in a wide range of variants and functionalities. But instead of buying an expensive product, it is also possible to build a water filter yourself. This article provides all the important info about it, as well as detailed step-by-step instructions.

Except for packaged bottled water suitable for consumption, all water benefits from thorough purification before it is fit for human consumption. But why is it useful to filter water?

Even if the tap water in Germany is basically clean, the drinking water quality can be improved a good deal with the help of a water filter. Not only can unhealthy pollutants enter the water, for example through old lead pipes, but lime and chlorine are also reduced through filtration. This improves both the compatibility and the taste of the drinking water.

Water filters are also ideal for traveling when water sources other than the tap at home are used. Even if a stream looks clean at first glance when hiking in the mountains, there are many microorganisms and suspended matter in the ground and surface water that are harmful to the human body.

Gastrointestinal diseases or even chemical poisoning, for example due to an increased nitrate content in the groundwater, can be the result. Since it is not at all easy to recognize and treat symptoms of water poisoning, it is better to prevent the occurrence of these diseases in advance by thoroughly cleaning the water.

Industrial water vs. drinking water

Water does not have to be purified at the same cost for every purpose. A distinction is made between two different levels of water quality: drinking water and industrial water.

Drinking water is considered the most important foodstuff for humans and is therefore subject to strict specifications in terms of quality, taste and appearance. Not only water intended for drinking must meet these requirements. Water for food preparation, for cleaning objects that come into contact with food, and water for personal hygiene are also subject to these high quality standards.

For other applications, however, it is sufficient to use so-called service water, also known as industrial water. Typical uses include garden watering, toilet flushing, surface cleaning, and in some regions, running the washing machine. Industrial water is usually obtained from rainwater, river water or a groundwater well.

Even if the service water must meet significantly lower quality requirements, some regulations apply here as well: It is important that the service water contains neither salt nor lime . Under no circumstances should the industrial water be used for the preparation of food or beverages, just as little as for cleaning the human body.

To ensure that water purification is as efficient and ecological as possible, it makes sense to divide up the water requirements precisely: How much drinking water is needed for what? Where is it sufficient to use roughly cleaned service water?

Advantages of water filters

The use of water filters brings a lot of advantages. Not only are harmful substances filtered out of the water and the taste is improved, but household appliances also benefit due to a lower lime load.

Water filters are also:

  • Cost-effective
  • time-saving
  • ecological
  • easy to use

and thus ideally suited for home use. Instead of lugging boxes full of mineral water and polluting the environment with the production of plastic bottles, water filters can prepare clean drinking and utility water in no time at any great cost.

Water filter for home

Residential water filters are a big trend because the benefits of great-tasting, clean drinking water are clear. Thus, a water filter can be used to upgrade contaminated water into clean industrial or drinking water and effectively protect people and animals from disease and pollution.

There are several models among the water filters that work with different mechanisms. For example, a reverse osmosis system can be used to produce osmosis water at home, or ultrafiltration can be used to produce ultra-pure drinking water.

But it is not always necessary to buy an expensive product. With some tools it is possible to build a water filter yourself. This usually works mechanically and mimics the natural purification of groundwater through the various layers of soil and sand – as these provide clean, uncontaminated water.

Materials needed

For a homemade water filter modeled on nature, only a few materials are needed. Depending on the desired size and the amount of water to be filtered, different containers can be useful: A water filter for on the go, for example, can be ideally implemented with a small bottle. Larger quantities of water can be filtered with buckets or canisters.

The following materials are needed for a water filter:

  • Pocket knife or cutter knife
  • Optional: drill and saw
  • For a small water filter: water bottle with lid
  • For a larger water filter: canister or bucket
  • Pebbles, ideally with rough surface for better dirt adhesion
  • fine gravel
  • Washed sand
  • Vegetable carbon
  • Fleece, absorbent cotton or fabric
  • A glass or other container in which the filter can be placed upright
  • Optional: wood to build a frame for a larger filter or a rope for suspension

Caution: Not every vegetable charcoal or charcoal is suitable for use in a water filter. Some coal has an increased salt content and therefore should not be used for water treatment. In case of doubt, activated carbon should be chosen, as it works optimally for water purification due to its dirt-absorbing effect.

Step by step guide

The structure and operation of a water filter are quite simple: the dirty water is gradually passed through the various filter layers. The multi-layer system is designed to gradually filter out smaller and smaller particles from the water. To do this, the various materials must be layered on top of each other in the appropriate order, as shown in the figure below.

  1. First, cut off the bottom of the water bottle or canister and drill a small hole in the tightly screwed lid .
  2. The bottle is filled upside down so that the large opening is at the top and the small opening is at the bottom.
  3. Scraps of fabric are now crumpled into the bottle so that the small opening is completely covered with it. This prevents sand and carbon from entering the filtered water.
  4. Above the fabric is filled with activated carbon, which filters the smallest particles such as bacteria and fine dust. The layer should be at least several centimeters thick.
  5. Over the layer of activated carbon comes an equally thick layer of sand cleaned with a sieve, which filters finer algae and small dirt particles.
  6. Gravel is then layered on top of the sand. This should settle well with a light shake. Gravel filters coarser dirt particles, such as insects.
  7. Pebbles are spread over the gravel so that the entire surface is covered. These serve as a coarse filter to screen sticks and leaves, for example.

Tip: Over the top layer of pebbles is recommended to place another layer of fabric. An old piece of clothing or a scrap of fabric is also suitable here, which catches the coarsest dirt and can be replaced after each filtering process.


The water that comes out of the tap in Germany must meet high quality standards and is therefore generally safe to drink. But despite the strict controls, there are many reasons to additionally filter the water before consumption. Old house pipes or especially when traveling or in nature, it is necessary to thoroughly clean and treat water before drinking. Water filters are available in a wide range of variants and functionalities. But instead of buying a water filter for on the go, there is also the possibility of building a water filter yourself. This article provides all the important info about it, as well as detailed step-by-step instructions.


Once the water filter has been completely filled with the materials, it can then be inverted into a glass or other container with the small opening facing downwards . It is important that the water filter has a firm stand. It is also possible to hang the water filter with a rope.

At the beginning of the filter start-up, it is recommended to run a few clean liters of water through the filter. In this way, final impurities can be removed, such as a deposit of coal dust.

To start filtering water, the homemade filter is now filled with dirty water. For example, it can be placed outside to catch rain. The treated water should now exit through the bottom opening and flow directly into the collection container. A good flow rate is about one drop of filter water per second.

Tip: To be able to filter as much rainwater as possible, a plastic bottle with a large diameter is recommended for the setup. If the yield of rainwater is too low, the filter can alternatively be filled with other water such as river or well water.


In order for the water filtration to work long and reliably, the water filter must be regularly maintained and its components renewed. With these instructions, the filter remains hygienic and works reliably:

Every few days to weeks, the gravel should be removed from the filter and properly washed with a sieve or replaced.

The plant, active or charcoal should also be replaced every few months.

If the water filter becomes clogged, it may help to gently agitate the surface and gently shake the bottle.

Especially if the water filter is used only rarely or with little water, germs will accumulate in the filter over time. Fortunately, building a water filter yourself does not take long, nor does it pollute the environment. Therefore, it is not a big deal that a new filter should be built regularly for hygienic reasons.

Mobile water filter

When you’re outdoors, you rarely have the option of taking a bulky water filter with you. Mobile water filters, which have a compact microfiltration system, are suitable for this purpose. In addition to bacteria, viruses and protozoa, the handy filters also remove suspended matter from the water.

However, heavy metals, salt and chemicals cannot be eliminated with microfilters. Therefore, they are not suitable for filtering heavily contaminated water or seawater. Professional water filters should be used here.

An alternative for water purification on the go are chemical water purification tablets. With the help of chlorine or silver ions, these additives manage to kill germs and rid the water of microorganisms. However, if the dirty water is cloudy or heavily contaminated, water purification tablets are not enough to make the water drinkable. Here, it is recommended to use a mechanical filter first and use the tablets afterwards.

A disadvantage of chemical water cleaning is the long exposure time. In order for the substances to develop their full effect, they often have to work in the water for several hours. In addition, the chemically purified water is not tasteless, but has a slight taste of chlorine.

Natural filters for outdoor experts

You don’t always have a suitable plastic container with you when you’re on the road, so you can build the filter station according to instructions. However, instead of using a water filter with plastic bottle, you can use materials from nature. For example, thick bamboo is ideal, although it is not naturally common in Germany. Thick reeds or other plants with hollow plant stems or a hollow trunk can be used as an alternative.

The design of the water filter is quite similar to the above alternative with a PET bottle. Wide leaves, for example, can be tied together to create a funnel through which the water can flow and exit drop by drop at the bottom. Here, too, the use of plant or activated carbon is important in order to be able to filter out finer dirt particles from the water.

Boil water – remove germs

Build your own water filter is a great way to rid water of contaminants and significantly improve water quality. In many cases, this can already be enough to achieve drinking water quality: If the water is not too polluted, multiple filtration with the homemade filter is often enough to make the water drinkable.

However, to be on the safe side, it is always recommended to additionally boil the filtered water. To do this, the water should be boiling for at least seven minutes, so that all microorganisms and germs are reliably killed.

Here, too, nature can come to the rescue: If you’re traveling outdoors and don’t have a gas stove handy, the filtered water can also be heated with the help of sunlight in sunny regions. To do this, it should be placed in black containers in the heat for at least an hour, so that a large number of pathogens are killed and the water becomes more tolerable for humans.

Unfortunately, even boiling water cannot completely remove all contaminants. Heavy metal contamination, for example lead, is not removed even by boiling. For the best possible drinking water quality, it therefore makes sense to combine various water treatment options. Following mechanical filtration and boiling, chemical additives can be used so that as many contaminants in the water as possible are eliminated and the water is of the best possible drinking quality.

Filter water

Phosphate in drinking water

Basically, we in Germany are blessed with good and above all drinkable tap water. Some drinking water reservoirs offer the perfect chemical composition, so that deposits of lime and corrosion in the pipelines do not stand a chance. However, this is rather rare.

Among other things, phosphate is present in drinking water. But what exactly is the purpose of phosphate in water? How does phosphate affect our health? Which limit values are decisive for humans and the environment? About all this and more we clarify in this article.

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How to shower with legionella?

Everyone has certainly heard of legionella. But hardly anyone knows what that is exactly.

Legionella is a genus of rod-shaped bacteria with the scientific name Legionella pneumophila. They stay especially in humid areas, such as drinking water. In small numbers, Legionella are a natural component of surface water and groundwater. However, a regular Legionella infestation can sometimes have serious health consequences for humans – such as pneumonia, the so-called Legionnaires’ disease.

Legionella can also be dangerous when showering, especially if the temperature of the shower water is not optimally adjusted.

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