Boiling doesn't help with cyanotoxins.
https://www.epa.gov/sites/default/files/2016-11/documents/ha...
> CAN I BOIL MY WATER TO MAKE IT SAFE TO DRINK?
> No, boiling water will not remove cyanotoxins and may increase toxin levels.
https://www.epa.gov/sites/default/files/2016-11/documents/ha...
> CAN I BOIL MY WATER TO MAKE IT SAFE TO DRINK?
> No, boiling water will not remove cyanotoxins and may increase toxin levels.
Yes, this.
Or we're assuming they don't drink all the water, in which case 20ml of the first solution will be less toxic than 20ml of the second.