Image via WikipediaFirst, let me start off the article by saying two things. First, I'm not a medical doctor. Use my advice at your own risk. Second, there are some risks associated with overexposure to silver, the worst of which is called argyria, which is basically a condition where the skin around your eyes, nails, and gums becomes discolored. Again, use my advice at your own risk.
Now that we have that settled, let me explain how to use silver to purify drinking water.
The process is pretty simple really. Basically, if you expose the drinking water to silver for a long enough time period, silver ions will disolve into the water. These silver ions will interact with the water to kill bacteria in the water. This process has been well known since the times of the Greeks and Phoenicians. In fact, the Phoenicians are said to have stored liquids in silver flasks to keep the liquids fresh for longer. More recently, the International Space Station also uses silver to purify drinking water.
The easiest way to purify your drinking water is simply to pour it into a silver flask, vessel, etc. and wait for a long time before drinking it. I'm not sure exactly how long you want to wait, but some of the sources that I've read suggest waiting about 3 days to make sure that the bacteria is dead.
If you want to wait a shorter period of time before drinking, you can speed up the introduction of silver ions into the water (and thus the purifying properties) by running an electrical current between two silver electrodes or by using "colloidal" silver. To use the electrolysis method, simply take two pieces of silver and use wires to hook them to the terminals of a battery. Then, place both pieces of silver close together (but not touching) in the water solution. Again, I'm unsure of the time that you have to wait until the water is safe to drink, but I would think that a few hours to a few minutes before drinking would be sufficient with this method. However, as I said, I'm not a doctor. Also, because I was unable to find the exact times that the silver should be in contact with the water before it's safe to drink, I recommend only using this method in an emergency.
If you want to use colloidal silver, you can purchase this at many health stores. Basically, colloidal silver is a mixture where microscopic silver particles are mixed in solution with a liquid. In these cases, carefully follow the recommendations of the solution maker as to how much of the colloidal solution you should mix in per liter of water.