Hydrotechnical Construction, Vol. 35, No. 4, 2001 WATER RESOURCES AS A BASE FOR THE SUPPLY OF DRINKING WATER A. P. Svintsov Fresh water is among the most intensively used natural resources. It is employed in practically all spheres of economic life and is of fundamental importance in the development of individual regions of the country as well as maintaining the living standards of the population, since there is no equivalent product which could replace it. The reserves of fresh water in Russia amount to around 10% of the world’s river flow, which at present and in the distant future is entirely sufficient for meeting vital needs. The annually renewable resources of river flow in Russia amount on average to 4,300 km 3 [1]. There is, on average, 30 km 3 /yr of renewable river water per inhabitant of Russia, as compared to 4.6 km 3 /yr per inhabitant of Europe. The conquerable figure for Asia is 5.2 km 3 /yr per inhabitant, and for the entire Earth 9 km 3 /yr per inhabitant. It is thus extremely important that this national property which Nature has provided us be used rationally. In 1996, the water supply derived from natural sources amounted to 92 km 3 , or 2% of all renewable resources (Table 1). In a number of regions with highly developed irrigation farming and industry it exceeds 40% [1]. Water is needed in large volumes by industry and concerns in the energy sector and agriculture. The principal customers of fresh water include concerns in ferrous and non-ferrous metallurgy, and in the chemical, petrochemical, oil, gas, coal, forestry, and paper and pulp branches of industry, their own facilities transmit on the whole about 360 km 3 /yr. Significant volumes of fresh water are used by cities and population centers for economic and drinking water needs. In the Russian Federation, 1,067 cities (98% of the total number of cities) and 1,682 urban-type settlements (84% of the total), along with 31,000 rural population centers (21% of the total), have centralized water supply systems with a total capacity of their water supply lines of 90,000,000m 3 /day [1]. The principal operational indicators of the water supply lines of Russia are characterized by the data presented in Table 2 [2]. Surface water, which amounts to 68-70% of the total volume of the water supply, serves as the source of the centralized water supply system in cities and other population centers. For example, the natural supply of surface water from reserves located on land within the Volga River basin amounts to 258 km 3 /yr, or 2.7 km 3 /yr per inhabitant. St. Petersburg draws from the Neva River and uses and returns to the river 1.2-1.5 billion m 3 of water [3, 4]. However, the distribution of water resources over the landmass of Russia is highly nonuniform. Roughly 80% of the rivers flow in the sparsely inhabited regions of the North, and a significantly smaller number of rivers are found in the rest of the country where 75% of the population dwells and where 70% of the industrial output and output from agriculture is produced. Surface water supply sources are basic for large cities, whereas small cities use mainly water from underground sources. The water from surface sources is, in most cases, subjected to purification since the water in practically all pools deviates from requirements which are imposed by customers. Substances of mineral and organic originas well as microorganisms are found in water from natural sources of water supply. The mineral composition is determined by the characteristics of the soil layers while the organic composition is created as a result of compounds that have eroded from rock or were formed in the particular pools as a result of biochemical processes. Mineral and organic impurities may also be introduced into pools from raw sewage generated by population centers and industrial concerns. Strict regulation of river discharges and the construction of reservoirs together lead to an increase in the areas of shallows and a sharp reduction in flow rates. These factors together cause a worsening in water exchange. The resulting increase in the content of dissolved organic pollutants produces conditions that promote the development of plankton, increase the color index, and create specific aftertastes and odors in the water. Different types of pollution from agricultural fields introduce atmospheric precipitation into natural surface water. As a result, heavy metals, petroleum products, phenols, and other anthropogenic substances enter the water systems. Water quality in certain segments of the rivers of the European and Asiatic parts of the Russian Federation is characterized by elevated concentrations of phenol (up to 7-8% the maximum permissible concentration), organochlorine pesticides (up to hundreds of milligram per liter), nitrogen ammonium and nitride (up to 10-16% the maximum permissible concentration), petroleum products (up to hundreds and thousands of percent of the maximum permissible concentration), and Zn, Cu, and Pb ions (tens of Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 4, pp. 42-46, April, 2001. 0018-8220/01/3504-0201$25.00 c 2001 Plenum Publishing Corporation 201