Non-ionic surfactant aggregates

A non-ionic surfactant emulsion aggregate, the aggregate being in the form of discrete water in oil microemulsion droplets, the aggregate comprising a water insoluble biocidally active ingredient having a required hydrophilic-lipophilic balance (Required HLB), a non-ionic surfactant system, and water, the aggregate having aggregate diameters less than 100 nanometers and being substantially free of organic solvent, the non-ionic surfactant system comprising first and second non-ionic surfactants, the first non-ionic surfactant comprising at least one primary non-ionic surfactant being soluble in water and having an aqueous cloud point greater than 25° C., and the second non-ionic surfactant comprising at least one non-ionic cosurfactant being insoluble in water and having an aqueous cloud point less than 25° C., proportions of the primary surfactant and the cosurfactant matching the Required HLB of the active ingredient, wherein the water is present in the non-ionic surfactant aggregate in an amount in the range of 0.1 wt % to 6.8 wt % and wherein the surfactant system is present in the non-ionic surfactant aggregate in an amount in the range of 57.5 wt % to 75.34 wt %, the active ingredient is present in an amount of between 10 wt % and 15 wt %, and the non-ionic surfactant aggregate has no tendency to phase separate across a temperature range of 0 to 50° C. at a water hardness of 0 to 1,000 ppm calcium carbonate.