Today two tanks of Rodnik system of cargo ship are filled by "silver" water.
For the American WRS or general disinfection purposes?
Hey, here's something I actually know about!!
For the Russian segment, all water used must be "Moscow" water, ie water that has been treated with Moscow type disinfectant, which uses silver nitrate instead of our chlorination process. The reason given for this requirement is that the Russian equipment that deals with water, such as Elektron and the condensate collectors, allegedly would completely disintegrate (or in other terms, work out of spec) if non-Moscow water passes through them.
This requirement means that any water shipped to the Russian segment via Shuttle must be imported from Russia.