Then don't drink it.

[Sherlock grits his teeth a bit while he's working. It's easy enough to flush his own wounds, but it's different doing it to someone else's.]

Do you have anything for the pain?

[He sets the distilled water down and scoots the glass of regular water to the edge of the table next to the pickled one.]

Local anaesthesia? I think the morphine I've got's been expired for three years.