Using wasserloeslichen grafted natural materials as a water treatment agent

Described is the use, as water-treatment agents, of water-soluble graft polymers obtained by the radical-initiated polymerization of (A) monomer mixtures containing as monomers monoethylenically unsaturated carboxylic acids, their alkali-metal salts and/or their ammonium salts, in the presence of (B) monosaccharides, oligosaccharides, polysaccharides, oxidatively, hydrolytically or enzymatically degraded polysaccharides, chemically modified mono-, oligo- or polysaccharides, or mixtures of these compounds, in the ratio, by mass, of A:B of (95 to 20):(5 to 80).