Last years in the area of soil science for the soil-plant system and in medico-biological literature is widely discussed a role of the activated water in a metabolism processes. Activation means increase penetration capability of water in separate organs and tissues of alive organisms. The factors making active water are: thermal, electric and electromagnetic processing, magnetization, freezing - thawing, mechanical operation, saturation by air and ozone, etc. As a result of external influence each unit of volume of water receives energy, collapse hydrogen communications that promotes formation of free radicals or change of properties and structures of units – clusters, responsible for physical and chemical properties of water. During activation long molecular rows (Н2О)n are broken off. It leads to change of size concerning the integrated characteristic of water – factor of a surface tension σ. Measurement of factor of a surface tension was carried out by a method of definition heights of water rising on capillary tubes by cathetometer. In all experiments cleanliness, temperatures constancy (t=26 ОS), height of water in a ditch, depth of immersing of capillaries, etc. was strictly supervised. Measurements of superficial tension of the distilled water are control instrumentation. Presented the average values of σ, measured simultaneously by three capillaries. Saturation of water with air and ozone was made in a glass tube in height of 1 m and diameter 40 mm. Air or ozone entered through fine-dyspersated dissector from the bottom part of a tube within 22 minutes. At speed of submission of gas of 4 l/min the charge of air on volume was 88 liter, in which oxygen О2 made on volume 18,48 liter and on weight 26,4 g from which in one liter of water 67,88 mg are dissolved. At the same speed of submission of a mix of air and ozone the charge of ozone on weight made 352 mg from which in one liter of water 9,68 mg are dissolved. The quantity of the gas dissolved in water was calculated by Henry's law. Electric processing of water was made in a glass tube in height 7,5sm and diameter 30 mm. One of electrodes (a spiral was made from the enameled copper) was inside of water, and another surrounded a glass tube outside. As can be seen from the table, value of factor σ for the fresh water taken from a city water line, almost coincides with factor for the water sated by air. This concurrence, apparently, is connected by that water in a water line moves powerful pumps, is chlorinated, therefore it has the overestimated gas saturation. Ozonization of water considerably reduces its surface tension. It is visible, that after 22 minute mixing with ozone (time of saturation of water by ozone makes 22 minutes) the factor of a surface tension of water decreases up to size of 58,35•10-3 N/m, that a 8% less than a surface tension of water before ozonization. Let's note, that we had been measured a surface tension of the same ozonized water in 1,5 hours after ozonization (time of disintegration of ozone in water of ~20 minutes). Experiences have shown, that the factor σ for this case makes size of 62,32•10-3 N/m, that almost coincides with factor of a surface tension of initial water without ozonization. The increase σ in size from58,35•10-3 N/m up to 62,32•10-3 N/m speaks decomposition of ozone already through 20 minute sediment. And in 1,5 hours the part of hydrogen communications is restored and σ grows. Small reduction of a surface tension is observed and for thawed water, and also the water subjected to electric processing. In our experiments, at 5 minute influence by the one-barrier charge by a pressure 16 кV, a current tens µА and with frequency 20 кHz the superficial tension of water has size of 61,8•10-3N/m. Thus, ozonization, electric influence and freezing lead to decrease in a surface tension of fresh tap water. From them the greatest appreciable influence on water makes ozonization. It means ozonized water is more active and the most desirable for system soil-plant.