Small quantities of silver are bacteriostatic or bactericidal. As a result, it is at times used in disinfection of pools and spas, as well as in water filters. However, the presence of silver in water is generally indicative of pollution from mainly film manufacturers, film processors and surface finishers. In fact, silver levels are closely monitored in these sectors since its presence can cause discoloration of the skin, eyes and mucous membranes.