The construction of the Trans-Siberian railway, the most largescale infrastructure project of the Russian Empire, was accompanied by the solution of a number of problems for the normal operation of this railway. One of them was to supply it with water, suitable for both industrial and domestic purposes. In conditions of time deficit, limited financing and taking into consideration natural and geographical peculiarities of the territory, it was necessary to look for ways of water supply organization which demanded new technical solutions. The various aspects of this problem have not received sufficient coverage in scientific publications, but they are certainly of interest to researchers. The construction of railway water mains was usually preceded by hydrological investigations to determine the most convenient water sources for each station, its properties, and the routes of communications. Additional difficulties often arose because no definitive conclusion about water availability and sources had yet been reached when locating the stations along the main line, and the surveying of the area was still ongoing. As a result, some of the stations were not well located for constant water supply, which required additional funding and engineering effort. Rivers were considered as priority sources of water to be supplied to Trans-Siberian stations and junctions, they were followed by streams, lakes, springs, groundwater and marshes, artesian wells. When selecting a source of water supply, the average daily volume of water consumption of a particular station was necessarily taken into account. At the same time, to ensure an uninterrupted water supply, the selected source had to have a minimum daily flow rate that was twice as high as the maximum daily consumption, which also made it difficult to solve the problems of the construction of railway water pipelines. Despite all the difficulties, the result of the large-scale works was the construction of new variants of water supply and purifying systems on the most part of the Trans-Siberian railway that functioned also in permafrost conditions.

At the turn of the 19th and20th centuries, the growth of urban population and development of urban infrastructure were accompanied by the emergence of environmental problems, including the increase of river pollution, which might cause water supply diffi culties. The central and local authorities, as well as representatives of various public, scientific, professional organizations and business circles, were involved in solving these problems. The order of their interaction could be diff erent, but these joint projects made it possible to achieve the best results in combating river pollution caused by industrial and domestic waste, to determine priorities in the system of water protection and to improve the supply of potable water to the population. Thanks to the activities of such organizations as the Society for Assistance to the Improvement and Development of Manufacturing Industry, Russian Water Supply Congresses, sanitary stations, and the Provisional Committee for the Development of Measures to Protect the Water Bodies of the Moscow Industrial District from Pollution, a rather extensive set of measures was carried out to study the properties, nature, and degree of water pollution in the rivers that served as sources of water supply for city dwellers, and the most eff ective methods of water purifi cation were determined in experiments. Practical recommendations were developed on the use of the most eff ective and cost-efficient methods and facilities for industrial wastewater treatment. The best domestic specialists were involved in solving the identified problems, who utilized international and Russian experience. The lack of sufficient funding for water protection activities resulted in some initiatives not being or being only partially implemented. In addition, a number of practical measures which had been planned in this area had to be postponed because of the outbreak of World War I in 1914