The knowledge of composition of water to treat allows the design of more efficient treatment process for pollutants removal, considering also treated water destination (human consumption, civil or industrial use, recycling in working process, discharge in surface water). Effluents flow rate determines plant’s dimensions. Feasibility studies forecast assessment of return on investment, very important factor for choice of plant’s installation and treatment technologies, that needs an of different items of capital expenditures (CapEx), as building materials, and operating expenditures (OpEx), as energy consumptions, manpower necessary for plant management, maintenance and worn-out components replacement. In general, pollutants concentration and possible sub-products recovery allow a reduction of disposal fees. The planning includes the study of the best logistical solution, on the basis of evaluation of the more appropriate areas and available places for plant positioning. In some cases the use of mobile units represents the more convenient option.