The invention provides an aqueous formulation comprising:a) at least one anionic surfactant selected from the group of alkyl sulphates, alkyl ether sulphates and/or acyl glutamates,b) at least one amphoteric surfactant selected from the group of alkyl betaines and/or amidoalkyl betaines,c) 2-methyl-1,3-propanediol.It is provided according to the invention thatd) said formulation has a pH of 6 to 10,e) comprises no further preservatives for microbiological stabilization selected from the group consisting of:e1) authorized preservatives cited in Annex V of Regulation (EC) No. 1223/2009, ande2) multifunctional additives selected from the group of linear or branched, saturated or unsaturated aliphatic or aromatic hydroxamic acids having a number of 6-16 carbon atoms and aromatic alcohols of the general structureAr—；(CH2)n-OHwhere n=2-4.
