An aqueous microbicidal composition having two components. The first component is a nonionic surfactant with structure: R2O(CH2CH(CH3)O)3(CH2CH2O)5H, where R2 is a mixture of C8-C14 linear alkyl groups. The second component is a benzoate or sorbate salt. The weight ratio of the nonionic surfactant to the benzoate or sorbate salt is from 1:0.12 to 1:109.7646.