yea, like make it less lethal or something
The water should actually make it a bit easier to process, so that your stomach can take it in better. + I think it would be more uncomfortable for you, if you somehow would manage to down the SN, because you can't really throw up powder that easily, which might also lead to painful experiences.
Water doesn't hurt it's lethality, only thing that matters is the purity. As long as it's >95% (more then 95), it's lethal. No matter if taken with water.