This paper discusses issues related to operation of environment protection facilities in immediate vicinity of natural water reservoirs, including fresh water reservoirs, located above and below ground. The subject of this study is a municipal solid waste landfill located in southwestern Poland and its related facilities included in the technological processes of waste disposal, treatment, and recycling. The paper briefly discusses the construction process stage and the first stage of operation of the studied facility in respect of their future impact on the environment. At the present time, waste is used to obtain landfill gas for electricity generation and materials to be reincorporated or disposed of, i.e. construction debris (brick, concrete), structural steel, firewood, and plastics. The range of topics presented in the paper is in accord with the sustainable development tendency and the paper specifically focuses on potential hazards arising from presence and operation of facilities of this type (built at a time when environment protection regulations were less restrictive as to their location). Continuity and effectiveness of insulation membranes of landfills are important inasmuch as once such landfills are filled with waste and then closed and reclaimed at the final stage, it will be extremely difficult to identify sites of potential leaks of basins, whose expected lifespan is several decades or a few hundred years. If such leaks are found within this period, it will be necessary to remove reclamation layers and strongly thickened waste in order to reach them [12]. Then, new damage resulting from operation of heavy equipment might occur. Therefore, apart from standard protection solutions of landfills, additional warning systems should be applied for maximum elimination of environmental pollution hazards, the range of which can be supralocal or even supraregional. Such systems should precisely indicate the location of probable places of hazards. It is not about damage to facilities, including cells, but about safety of their surroundings. Due to the vastness of the topic referred to herein, the paper has been narrowed down to include only one issue, i.e. tightness of cells intended for non-hazardous and non-inert waste.