About water

Drinking water

Human body consists mostly of water. It contains approximately the same percentage of water as the surface of the Earth. Our bodies contain 23% of carbon, 2.6% of nitrogen, 1,4% calcium and trace quanta of more than thirty other elements. But primarily we are made of oxygen and hydrogen composed into that unique molecular combination called „water“. Water makes up some 4/5 of the weight of a suckling, approximately 2/3 of the weight of a grown up man and ½ of the weight of an old man. Sucklings and small children are thus most vulnerable to water insufficiency.

The organism can cope with the lack of water much worse than with the lack of food. The loss of already 20% of bodily water is fatal. Dehydrated man dies approximately within seven days. According to the Guinnes’s Book of records the man who withstood the longest without water was certain young Austrian whom the policemen forgot in the cell of arrest. Eighteen days later they found him on the threshold of death.

Healthy drinking water comes from healthy environment. The facts about the environmental problems in the Czech Republic are known as well as the data concerning the decline in the immunoresistance of the population, increase in the allergic diseases and relatively low length of life. The state of environment – and thus also the quality of drinking water – undoubtedly influences the health of population. The effects of contaminants sought for in drinking water are toxic, karcinogenic and mutagenic (affects the future generations), terratogenic (cause malformations of foetus) and often combined.

When comparing the effects of food and drinking water on people’s health we cannot overlook the basic difference: the food we can choose from a large variety of items. We can surely exclude from our diet fat belly-pork or at least exchange beef liver for the chicken one. But as for water, we drink it every day from the same source. Whether we obtain it from the well or from the public water system, it affects us daily. The importance of even very low concentrations of contaminants is thus multiplied as some tend to cumulate in the human body (such as arsenic, cadmium, lead), while the effect of others is late or there is even a threshold effect (specific organic substances as benzene, vinyl chloride, tetrachloroethene, etc.).

Continuous – i.e. everyday – influence of water on your health is a sound reason why to care about the best quality of your drinking water.

Contamination of drinking waters

In 1988 the world’s chemical industry produced some 800 million tons of chemical substances. Every seven or eight years the production doubles. Potential toxicity of waste ensuing from this production as well the toxicity of the products themselves are often hardly even tested. There are some 80 000 substances produced in significant quantities.

Present standards for drinking water respond to this immense quantity of chemicals pervading the environment beside others by the so-called group assessments of concentrations of number of organic substances contaminating drinking water. One example of the wide-ranging groups of contaminants are the omnipresent oil compounds, some of which are toxic even at very low concentrations. Also present in all the waters practically without exception are the polycyclic aromatic hydrocarbons originating from motor-vehicles and flushes from asphalt roads. A noticeable group of contaminants consists of the compounds containing organically fixed chlorine. These have a threshold effect and threaten human health in any, even the lowest concentrations.

Chlorine and its compounds

In the 70ies it was discovered in the U.S.A. that the so called trihalomethanes (chlorinated organic substances with carcinogenic and mutagenic effects) originate from chlorinated drinking waters. Based on the investigation carried out in the U.S.A., D. Moris proved that 9% cancers of bladder and 18% cancers of large intestine result from consumption of chlorinated water. Assessing these – and other – specific organic substances is very complicated and expensive. That’s why you cannot get proper information on their presence or absence in your drinking water from the usual concise water analysis available at the request of the clients for approximately 35 €. Complete analysis in the whole range of current obligatory standard is available for 700 €.


Natural conditions of nitrates’ occurrence in waters (about 2 mg/l) were gradually being affected by the growth of human settlements. Nevertheless, the unfavorable situation for a long time concerned just the underground waters in areas of concentrated settlements. As late as in 1960 it was stated that the surface waters in the Czech countries designed for treatment in water-plants contained only low concentrations of nitrates posing no risk to human health. In the same year 1960 the highest concentrations documented in the waters of Vltava, Jizera and Želivka rivers reached approximately 10 mg/l of NO3-; in 1980 the acknowledged concentrations were already three times higher – max. 29–34 mg/l. The use of nitrogenous fertilizers in Bohemia increased during that time four times from 100 000 tons in 1960 up to 420 000 tons in 1980 (recalculated to pure nitrogen).

That is the explanation of the nitrogen problem: the main reason of high concentrations of nitrates is the intensification (chemicalization) of agriculture, i.e., the massive use of nitrogenous fertilizers. They affect all the agricultural landscape.

The health risk posed by the nitrates (NO3-) ensues from the possibility of their bacterial reduction into toxic nitrites (NO2-) in man’s digestive organs. The nitrites compound in the stomach reacts with secondary amines from food to give carcinogenic N-nitrosoamines. Statistical data proved the dependence of increased occurrence of cancer of liver, stomach, large intestine and bladder on the concentration of nitrates in water.

In case of the methaemoglobinaemia of sucklings nitrates react with haemoglobin, making up methaemoglobin, a substance unable to transport oxygen. As for the methaemoglobinaemia prevention, the statistically safe concentration of nitrates in water is supposed to be 15 mg/l NO3-. The limit value is 50 mg/l NO3-. But the drinking water is not the only source of nitrates entering into the human body. Nitrates are present also in food, especially in vegetables. Removing them from it is impossible. At the same time vegetables are necessary for healthy nourishment of men. It is a valuable source of vitamins, trace elements and fibrous materials. As in case of bio-utilization of calcium and magnesium, the bio-utilization of nitrates from water is even higher than their utilization from organic substances, that is, for instance, from vegetables.

Using nitrates-free water you’ll considerably lower their total intake.

Water "Hardness"

One well known slogan concerning biogenic value of calcium and magnesium (necessary for building the bodies of organisms) says: "The harder the water, the softer the artery" – that is the lower the probability of cardiovascular diseases. Sometimes you can come across the opinion that the body receives Ca + Mg (so called bio-utilization) just in the form of organic compounds as chelates, lactates, citrates etc. These are contained only in some types of food (milk products) or in food supplements. It’s true that the organic form is highly bio-utilizable (about 60–80%) and that our organism is unable to receive calcium and magnesium from inorganic substances. But in water these elements are present in the form of dissociated ions and that’s why the bio-utilizability of calcium and magnesium taken from water is even higher than their bio-utilizability from the organic forms. And as we drink up to 2–3 liters of water daily, the contents of these elements in water is of an utmost importance. As for the human health, it is basically wrong to drink water deprived of Ca + Mg, i. e. water that was distilled or treated on the basis of reverse osmosis. Water deprived of minerals is so called "hungry water"; it takes minerals from its surroundings, even from the human body, thus causing a great damage. To drink at once some 5 liters of such mineral-free water can even cause death. Mineral-free water in which food is boiled takes important minerals away from the food – especially calcium and magnesium.

The new Notice of Ministry of Health No 376/2 000 assessing requirements on the quality of drinking water fixes the minimal content of calcium in drinking water at 30 mg/l and the minimal content of magnesium at 10 mg/l. Nevertheless, recommended values are higher: for calcium 100 mg/l, for magnesium 30 mg/l. More details see on web sites of the Public Health Institute.

Quality of water from water systems in Czech Republic

The last whole-scale survey of the drinking water quality in all the water-plant sources (not in the distribution networks) in the Czech Republic was made in 1991. According to the annual report of the Ministry of Agriculture on "Public Water Utilities in the Czech Republic" the share of inhabitants supplied from permanently or occasionally inconvenient water sources was assessed up to two thirds. Only one third of the inhabitants were supplied by permanently convenient water.

In the following years the whole-scale surveying of water quality was substituted by so called monitoring of drinking water quality which is now executed by the Public Health Institute in Prague. This monitoring takes into account several hundreds of thousands analyses of drinking waters which are available to approximately 50% of inhabitants supplied by water-supply companies. The data of the 1994 monitoring show that of the water-plants’ discharge 73% of the water samples were overchlorinated, 52% exceeded the limit of phenols, 38% exceeded the limit of vanadium, 21% the limits of arsenic, barium and mercury, 18% limits of chlorine, etc. Actual data on the monitoring are available on web sites of the Public Health Institute.

The well water’s quality

It is not being monitored, just assessed. In 1994 the survey was executed taking into account 125 wells in the Plzeň-South district. Comparison of the outcome of the analyses with the standard No. 757111 revealed that not even one well met the required standards. In most cases the standard was exceeded in 3–7 indicators. Taking into account a number of other local inquiries the Prague Public Health Institute in 1999 came to this qualified estimation: approximately 70% of wells may pose a health risk. This estimation concerns approximately 800 000 public, non-public and private wells on the whole territory of the Czech Republic supplying water to about 1.44 millions of population.

Established errors

It is the state that cares about the quality of water in public water systems. This assertion is the most wide-spread consumers’ error. It lost its formal justification as early as in 1993 when the privatization of eight originally regional water treatment and sewage disposal plants took place. Instead, at present there are some 3 000 private owners, 111 of them being important. This "Big Bang" caused much damage to the quality of drinking water. Nevertheless, the wide-spread illusion of state being responsible for the quality of drinking waters lingers from the past when the authorities cared not only of the quality of drinking waters but supervised also the taxation, living conditions and the world-view of the Czech citizens. Everyone is now responsible for all these items including his/her world view.

But there are more established errors:

How to obtain water for direct consumption?

Conviction or apprehension concerning the imperfect quality of drinking water from public water systems as well as from wells makes all the time more and more consumers to use drinking water treated at home by water filters or buy water in bottles.

Some recommendations to remember:

Contaminants and the cancer of large intestine and rectum

What can we do to prevent it? We should reduce the intake of carcinogenic substances. There’s a great many of such substances: let’s turn our attention to those relating to the GIT carcinoma including the large intestine and rectum:

1. Trihalomethanes, above all chloroform, which is the product of water chlorination, can be reliably eliminated from the drinking water by active carbon; this medium eliminates from the drinking water not only THM but also a number of other carcinogenic contaminants.

2. Nitrates and nitrites:

Nitrate and nitrite contents in food

Nitrate and nitrite contents in water

Recommendations for storage and consumption of food:

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