Water-soluble polymers are called polyelectrolytes and can be used in solid/liquid separation as flocculating agent or as flocculating additive (in combination with inorganic salts such as ferric chloride, ferrous sulphate, or aluminium chloride). For the basic investigations described below, polyelectrolytes were used as flocculating additives, i. e. added directly to the suspension. The polyelectrolytes are usually in powder/granular form and must be dissolved on site. While water with a low conductivity from a Milli-Q-Plus plant is used for basic investigations, in a sewage treatment plant in real-life applications, mostly supply water or well water is used. In the following, the influence of the solvent, the type, and time of energy input for dissolving the polyelectrolyte is described by characterizing the charge density. Flocculation investigations with this polymer were carried out on a kaolin suspension. Considerable amounts of polymer can be saved when used correctly.