well first off i don't think lime water is essential for health, i am sure you can get calcium in other forms just as well. having said that, the amounts of "toxic" substances you list in pickling lime doesn't bother me one bit. ALL of those things are in a whole host of foods you ingest, and in larger amounts.
if you did a chemcial analysis of just about any herb on earth you would find trace amounts of all kinds of "toxic" substances. so what? we human are able to handle these substances in the 10 or 15 ppm range. if you ate nothing at all with any trace amounts of these "toxic" substances, you would starve to death.
silver is also a "toxic" substance. eat enough of it in any form and you will have a toxic reation. and yet in small amounts it therapuetic. same with gold. same with lots of other metals.
every single liquid trace mineral supplement (including the ones derivbed from plants) in the world lists all kinds of hevy metals in trace amounts. i take one derived from humic shale everyday and it works wonders for my brain and mental clarity.
lets get that lab to do that same chemical analysis of your favorite health food or supplement and see if it doesn't come back with some trace amounts of horribly toxic metals. i am sure it would. they are part of the soil, they are part of nearly every plant on earth, and part of our bodies. too much will kill you, but its impossible to avoid them.