A biocidal additive formulation comprises a silver containing glass particle, and a combination of at least two metal based compounds. A metal in each of the metal based compounds is selected from the group consisting of silver, copper, zinc, mercury, tin, lead, bismuth, barium, cadmium, chromium, titanium, and a combination thereof. Another biocidal additive formulation comprises a silver containing glass particle, ZnO, and Bi2O3. A glass substrate possessing a durable biocidal property and an article possessing a durable biocidal property are also provided.