This may not be a totally off the wall question, considering the sad state of affairs around the world:
Should the world go totally awry and the only water you have around is your pool, and the only chemicals you use are liquid chlorine and CYA, what would you have to do to be able to safely drink your pool water? The CYA MSDS only refers to toxicity as:
Toxicity to Animals:
Acute oral toxicity (LD50): 3400 mg/kg [Mouse]. Acute dermal toxicity (LD50): >5000 mg/kg [Rabbit].
These are pretty high levels, but I still would not feel comfortable drinking the pool water as is.
It looks like the CYA may be extracted by distillation, evaporation, etc.