There was a situation recently where a containter of Hydrochloric Acid and one of Sulphuric Acid were poured down the sink in the belief that they were distilled water. A dozen other containers of real distilled water were in the same place and the acid tubs were simply mistaken as distilled water because no labelling or other identification was applied. No apparent damage was done but that is not to say that something drastic could not have happened as you would be aware.
Labels could be used of course but there were lame responses that labels could be worn off or washed off or any of a dozen other excuses for not using them.
I was wondering if there was an inert coloring agent that could be mixed into the acid containers to indicate that they are something other than distilled water?