The present invention relates to a biocidal composition including at least one active biocidal compound and at least one nonionic or anionic exopolysaccharide (EPS), the active biocidal compound being selected from at least one triamine having the following formula I, R1NR2R3, formula I where R1 is an aminoalkyl radical comprising a straight or branched chain having 2 to 16 carbon atoms, R2 is a hydrogen atom or a straight or branched alkyl chain having 1 to 18 carbon atoms, and R3 is, independently from R1, an aminoalkyl radical comprising a straight or branched chain having 2 to 16 carbon atoms or a —CH2—CH2—CH2—NH—R4 radical, where R4 is a saturated or unsaturated fatty acid chain including 4 to 20 carbon atoms or a mixture of C4-C20 alkyl chains, characterized in that the biocidal composition includes, by weight and relative to the total weight of said biocidal composition, 0.5 to 90% of the biocidal compound and 0.1 to 10% of the exopolysaccharide.
