How is our drinking water?

This is usually the first question which people ask a water expert, when they meet him. The information level of the population is rather low. In the past, contradicting information has been spread. This is understandable, if taken into account, that the level of analytical techniques and reliability of analytical results, are not always as high as one could wish. Further, the treatment technique has several times been changed leading to different water quality.

This article was written to describe some facts and consequences without going to much into specific details. The majority of the people know, that drinking water in Kiev and in the majority of other Ukrainian cities, is prepared from river water. River water contains many organic substances. The bigger amount of them can be classified as humic substances of natural origin. During the summer, the concentration of organics can be increased because of plankton (algae, bacteria), plankton excretes and degradation products. If this type of water is mixed with chlorine for disinfection, chlororganic compounds will be formed. To reduce the necessary doses of chlorine ammonia (NH3) can be added leading to the formation of chloramines. Chloramines have a negative impact on aquatic organisms and can be found even after sewage treatment.

The formation of chlororganics because of disinfection is known already more than 20 years. Type and quantity depend on many factors as for example:  type and concentration of organic matter, temperature, time of contact and so on. Some compounds, as chloroform, will be formed in higher concentration only during the vegetation period. Others can only be found using analytical instruments that are not available to the analytical control services or that are not included into standard surveys. Because of the big amount of dangerous compounds, one has to admit, that the volume of work for a permanent control would be by far too high.

A possible solution of this problem would be, to determine the amount of chlorine bound in organic compounds. Such analytical results that were collected by the author of this article in the past, showed, that chlororganics were present in the drinking water all over the year. Their concentration could be evaluated as "very high" but have decreased in recent years. What is meant by the assessment  "very high" ? The quotation marks were set to point out that this is an evaluation, based on actual knowledge and assumptions. The assumptions have to be made for the quantity of daily water consumption, for the number of years of consumption and for adults and children separately. One also has to ask if there are other factors important for the health, as various harmful substances in air and food products, wrong nutrition, smoking, etc.

These remarks should point out that a reliable health evaluation for the Ukrainian population is still not possible. We can however take into consideration some American studies. MORRIS, CHALMERS and some other colleagues from Harvard University (1997) summarized the results from several studies. They conclude, that people drinking chlorinated water more than 10 - 15 years, have an increased risk to get bladder cancer (21 %) and rectal cancer (38 %). Many other publications show in the same direction. These results are important also for Ukraine. It can be assumed that the situation here is even worse.

Other harmful compounds that occur in drinking water are obviously less important. Nitrate and heavy metals, for example, can be found but only in “small” concentrations, radioactive substances and pesticides occur at certain times, but information about these substances is rather insufficient and therefore not reported here. 

  Perspectives

The aim of a future drinking water policy should be to give up the direct use of surface water and chlorination. As soon as possible, water protection zones should be selected and protected within the river valleys; they also will serve for nature protection purposes. When ground water is extracted here, it can be enriched with river water already filtered through the underground or by artificial infiltration of river water. The raw water from these places will contain less organic matter and a much smaller quantity of bacteria than river water itself. In this case, disinfection will be necessary only after treatment and filtration in the water work. Expenses for technical changes are rather small, in comparison with the economic damage caused by illness and reduced life expectance.