the assembly of the plane plates furthermore strands or wires may eventually be stretched from one end to the other of the path in order to effect the prestress by adhesion of the concrete in the vertical direction of the tank formed by the plane plates it is clear that the casting may be carried out either on forms positioned vertically and provided with vibrator elements in order to tamp the concrete or on horizontal forms and in this latter case the smoothing and finishing of the inner surface of the plane plates is carried out by means of outer vibratory finishing equipment the installation of the tank according to the invention is carried out in the following way knowing the desired capacity of the tank the number of plane plates required in order to construct a tank meeting the required characteristics is determined if the capacity of the tank is towards the lower limits of the range of variation of the capacity a tank having a square base will certainly be chosen that is to say a tank made of plane plates forming between them an inner right angle for higher capacities a tank will be chosen which has a pentagonal hexagonal heptagonal octagonal.