When making your own colloidal silver, you should only use pure distilled water with no added ingredients. Anything but pure water will produce compounds that are not healthy or safe for use.
Be sure to check the purity of the distilled water with a TDS meter. The meter should read no more than about 3ppm. Checking the purity of the water before making CS will ensure the quality and safety of your product.
Tap water usually measures between 30 to 150ppm. The impurities in tap water combine with silver to produce unsafe compounds that can cause conditions like argyria. Argyria is the scientific name for blue skin condition that many use as a reason not to use colloidal silver.
Argyria is not caused by using pure colloidal silver made with distilled water. This condition is caused by consuming large amounts of silver compounds that come from using impure water, not safe concentrations of pure colloidal or ionic silver.
As well, some people think that adding salts to the water will speed up the generating process. This is also a very unsafe practice. The salt will add chloride to the water and create unsafe silver compounds.
The scare tactics of blue skin should not be a worry. The only colloidal or ionic silver product should be made from pure distilled water and pure silver wire. Any other mixtures should not be used.
Pure distilled water and pure silver wire will give you a pure, safe product.