The dangers of polluted water are well known, so I only briefly recall the main sources of danger here. In the further course, I discuss the methods with which you can win drinking water on the way.

Dangers due to polluted water

The dangers of polluted water are well known, so I only briefly recall the main sources of danger here. In the further course, I discuss the methods with which you can win drinking water on the way.

Germs and pathogens like to adhere to particles and suspended matter. But even seemingly clear water can be contaminated by minute, invisible germs. The pollution of waters is mostly due to livestock and grazing, faeces, waste or chemical pollution. Pollutants such as fuel, chemicals such as fertilizers or pesticides are also found in the water.

Distribution of the pathogens in the water

In the water source pathogens are distributed differently: At the bottom, in the mud, multiply bacteria by the nutrient supply very quickly. Higher temperatures at the edges of the water or directly at the surface also promote growth.

Water near settlements and agricultural land is more likely to be polluted than in less used terrain. The closer water is taken from the source, the less likely it will be polluted. Mountain streams above pastureland are generally less polluted. Water from a well in the middle of a pasture area is more likely to contain pathogenic germs. Here is another difference: Water from fast-flowing waters is usually safer than water from stagnant water, as the dilution is greater in fast-flowing waters.

Many diseases that are transmitted by polluted water, at least the end of the tour, if not worse. Therefore, a sterilization of drinking water is important.

In order to understand the various possibilities of drinking water treatment, a brief excursion into the world of germs and pathogens is necessary here.
 

parasites

Parasites are living things that nest in their host and feed on it. They can live in ponds and lakes and drop their larvae there. Water serves as a transport medium for the pathogens or as a habitat for intermediate hosts. When the person drinks this water, the parasites enter the body. As a rule, these are worms or their larvae.

protozoa

Unicellular animals (0.001 - 0.015 mm), so-called protozoa, can be another source of infection. Pathogenic protozoa include amoebic dysentery (Entamoeba histolytica), Giardia, Lamblia, and Cryptosporidium. These hard-shelled parasites form cysts that can be dangerous to humans. Particularly feared are amoebae, which are found worldwide and are particularly native to subtropical areas. However, due to their size, protozoa are easy to filter out of the water, and chemical disinfection requires a long contact time of up to two hours due to its durable membrane. Impurities with protozoa can enter the drinking water via animal and human fecal matter.

bacteria

Bacteria are unicellular organisms (0.0002 - 0.005 mm), which can enter water bodies through sewage or other organic substances and can multiply there very rapidly, depending on environmental conditions, especially in heat and nutrient-rich water. Pathogenic germs, which often cause diseases through contaminated drinking water, are for example Escherichia coli, Salmonella (Salmonella typhimurium) or Cholera (Vibrio cholerae).

virus

Viruses enter the circulation mainly through animal and human feces and can only multiply in living cells. Its minimal size (0.00002-0.0002 mm) makes it difficult to mechanically filter it. However, viruses are sensitive to heat and chemical disinfectants. Known dangerous viruses are the causative agents of hepatitis A, Norwalk virus, Rota virus or the polio virus. Special care should be taken in the vicinity of settlement areas, as the viruses prefer to reach the drinking water via wastewater.

Chemicals and heavy metals

Activated carbon is capable of dissolved organic trace substances such. B. pesticide agents and their metabolites or drug residues by adsorption of these substances from the water to remove. The more non-polar the substances are, the better they are adsorbed on activated carbon. In contrast, ionic substances such as minerals, salts and lime remain in the water. 

(Swell: wasserklar.net / Wikipedia)
 

Methods of disinfection on the way

Here I present the most common methods of water treatment on the way.

scald

Decoction is an easy way to sterilize drinking water. For this purpose, the water is heated for at least 5 minutes until it bubbles. Thus, almost all germs are killed. In this process, however, neither suspended solids nor chemical impurities are removed from the water. In addition, the fuel consumption increases. Therefore, the decoction of water is safe, but not really recommended for outdoor tours.

chemistry

Many pathogens can be rendered harmless by chemical disinfection. Chlorine, silver and iodine are the most common chemicals used for drinking water treatment and preservation. For example, Micropur from Katadyn, which is available as tablets or in liquid form, is known. In chemical disinfection, it is important to adhere to the recommended contact time: with Micropur this is at least 2 hours. Only then can it be assumed that pathogenic agents have been killed. If the water still contains any visible suspended particles, personally I would even increase the contact time. Due to the low weight of the tablets or drops, this method is well suited for tours with the backpack, with some advance planning, the use of chemical disinfection is easy to handle. However, the treated water can easily taste like chemicals like chlorine.

UV radiation

Like chemical cleaning, the killing of germs by UV-C radiation works. The prerequisite is, however, that the water is clear and free of suspended matter, since germs adhere to it and can not be killed.

Mechanical filters

Mechanical water filters remove suspended matter, bacteria and protozoa from the water. The membrane of the filters hold back the particles that are larger than the pores. Depending on the filter, the size of the pores differs. Everything that fits through the pores of the filters, so for example, viruses that are smaller than 0.0002mm, so can not be filtered and thus remains in the drinking water. Many viruses are much smaller and can only be accessed through additional decoction, chemical disinfection or sterilization by UV radiation be killed. In the case of risky water sources, the methods should be combined, for example pretreated with a filter, and then kill the remaining remainder of the pathogens with chemical disinfection.