Even standing in your clean house, you are bombarded by dangerous gamma rays, which cause cancer fer sure, but you may not get cancer in your lifetime.
I concede that my statement:"If a microscopic piece of radioactive material gets into your body, you WILL get cancer -- may not happen for 10 or 20 years, but it will happen. " --- is an overgeneralization and in that sense an exaggeration.
But then again, the original post claiming it would take "truckloads" of contaminant to poison a reservoir is, at least, as 'inaccurate'.
The basic idea is that there are radioactive materials that are granular enough and potent enough so that dispersal into a reservoir would compel you to NOT drink from it BECAUSE "you do not want radioactive material to be lodged in your body where its emmissions are damaging enough to your DNA to significantly increase the likelyhood of cancer"
I'll grant you your technical semantic objections to my assertions, to the extent that my non-factuality comforts you as you drink water that has been contaminated by radioactive materials.
Al Quaida DOES have credible plans for poisoning water supplies and just such a plan was busted in Italy. But it won't be done by putting stuff in reservoirs.
Actually, I am NOT at ease with the public water supply, for the reasons I mentioned (easy to poison from anyone's house...etc)
Low on my list is concern about radioactivity, because it can be detected rather easily at the source or destination.
I'm primarily concerned with faster chemical killers which are IMMEDIATELY dangerous to your life-span such as Cyanide and Arsenic, etc. These non-radioactive poisons can kill real fast while cancers can grow for years before they do any harm.
And what about hazardous gases commonly used around semiconductor processing facilities?? Arsine, phosphene...that can kill in such minute concentrations that no one actually knows what phosphene smells like, because no one has ever lived long enough to tell.
Get over your curie-phobia!! Radioactivity is not your biggest problem!