in chemical terms this is possible since it's not actually chrome. it's a layer of silver metal which gives it the brilliance and reflection, then a tinted topcoat to add that slight nickel coloring to make it look like chrome. if you listen carefully they specifically say that this is a chrome-like finish.
as for using de-ionized water, they use it simply because there are no impurities in it and it dries spotless so you don't ruin the silver finish.