World War I, as a total conflict, was accompanied by various manifestations of the barbarization of hostilities. One of the topical issues of the world confrontation is its impact on the ecology of the region of military conflict. Written on the basis of archival materials for the first time used in studying, the article traces the policy of the military leadership on the use of water resources during the war. Various plans and measures for flooding areas in the system of passive and active defense in different points of the theater of military operations are analyzed: in the defense of fortresses, construction of barriers on rivers to prevent their forcing, attempts to use river barriers for flooding of entire cities. The work studies the reasons for the successes and failures of such plans. In particular detail it does so in the context of the plan to flood the rivers of Polesye, which was the largest reservoir of water resources in the western borderlands of Russia in a strategic region of historical confrontation between Russia and its western neighbors. The article concludes that there was a serious disagreement between the military and civilian authorities on the issue of the detrimental effects of river flooding to the agriculture, population, and ecology of the area, including in the postwar perspective, which forced the military leadership to adopt a moderate defense plan for swamping the area. In the course of using water resources, the Russian army managed to avoid the barbarization of military actions, including flooding large contingents of the enemy, limiting itself to moderate measures of impact on the ecology of the region and remaining within the limits of humanity, as far as total war permitted.