Disclosed is a storage-stable aqueous concentrate for the preparation of a disinfectant, the concentrate comprising: hydrogen peroxide, colloidal silver, a stabilizer comprising at least one biopolymer and phosphoric acid to adjust the pH value of the concentrate to less than or equal to 3, characterized in that the concentrate comprises at least one sodium salt selected from the group consisting of sodium nitrate, sodium sulfate and combinations thereof the concentrate being essentially free of any synthetic organic complexing agents. The composition can be used to treat drinking water.
