Connect a 24V incandescent lamp in series with either positive or negative output lead. Insulation is shrunk over soldered connections using a heat gun or hair dryer. Pure silver is sometimes available at electroplating supply companies. Or, inquire at a jewelry store specializing in silver about who their wholesale supplier is. If the Silver Colloid is to be ingested or injected, be sure to use distilled water.
Tap water is fine for other uses, such as for a topical spray or for plants.
Also, before beginning to make your Colloidal Silver you will need to make a saline solution for enhancing conductivity. If you are using filtered spring water, no saline solution will be needed as spring water already has a natural saline content. If the saline content of the water is too high, black flakes will begin to appear on the surface of the water. Saline solution can be made by mixing approximately four ounces of distilled water with half a tea-spoon of sea salt in a separate container. Do not use common table salt as table salt has chemical additives.