"Some bacteria are tougher than others, as Clostridium botulinum will survive boiling water for a considerable time, although the toxin is destroyed."

The way I understand it, the Clostridium botulinum bacteria is easily killed by boiling (212F) for a few minutes, and it cannot grow in the presence of oxygen.

But if the live bacteria are transferred to an anaerobic (oxygen-free) environment, they will either turn into spores or spores will form [I'm not quite clear on this] and in that process of multiplication the toxins are produced. The spores are an alternate form of reproduction, and are extremely resistant to heat and other conditions.

Spores can survive 5 hours in boiling water, but can be inactivated in 4 minutes in an autoclave which provides pressurized steam (121°C, 15 psi).

So, even if you collect fresh water (contains oxygen) with Clostridium bacteria in it, it is usually harmless on its own, and boiling the water will take care of any problem.

And if I haven't got this straight, PLEASE correct me!

Sue