Is there a point beyond which water cannot be consumed even if you boil it? Assuming no chemical contamination, can you boil water to make it potable no matter how long it has been stored? The reason I ask is that I can envision a scenario where I have a whole lot of propane, a stove, a metal pot, and 40 gallons of water that has been stored at +90 F. for 3 months. Suppose that water is literally dripping with algae and assorted creepy-crawleys. Can it safely be drunk after straining and boiling, or will toxins (botulism, salmonella, etc.) which cannot be removed by boiling build up in the supply, thereby making it deadly?

To the best of my knowlage, After you have strained and filtered the water, then bringing it to a rolling boil the water is good to drink no matter how long it has been stored or wher it came from.

Well, you can filter the water for pathogens and other biologic organisms, and you can boil whatever might make it through long enough that you can destroy those organisms as well. However, some organisms create toxins which can pass through filters and will not be destroyed by boiling.

There are some organisms that live in the heated pools in Yellowstone that I think would be pretty bad if you tried to ingest them. I think they can tolerate up to 180 degrees F or so, but boiling may be just a bit too much for them.

Pasteurizing may be the best disinfectant process going so far as using heat to sanitize water goes.

And that right there is the rub. During the summer months I store 40 extra gallons of water (heavily bleached--more about that later) in the water tank of my travel trailer. During the day it gets to be over 90 F. (sometimes over 105 F.) I'm wondering if that water, if compromised by pathogens, can be made safe by boiling or is it risky no matter what?

If it is chlorinated and kept from the light...it shouldn't grow any baddies...and should be safe long after 3 months... BTW in my oppinion, it is more risky not to drink water when dehydrated than to drink questionable water.

That's a good question. To the best of my knowledge, all the crap that makes us sick tends to be either the organism, or a toxin made by it. Most toxins tend to be proteins, so I assume if you boil, you'll denature it and the protein will be rendered inert. But I've also heard that spores and prions are pretty robust. I wonder about them? I'll see if I can corner one of the microbiology professors in campus this week and give you a professional opinion!

I tend to agree with Silent Weapon: better to drink than dehydrate and die. After all, my dog drinks water from anywhere, and she's still around. You figure organisms have been dealing with the water on the planet a few billion years (if you believe in evolution), so I'm sure we can survive it still, generally speaking.

the best answer is the story of the guys "down under" in OZ
some years ago..on a long treck in the outback they found the
only water hole had a dead and very rotten roo in it..the
horses would not even drink it..sooo..they strained the water
thru blankets..boiled it..put ashes from the fire in and boiled
it more..strained thru the blankets and let it cool and drank
..it still had a nasty taste but no harm came to them...

I get my water by gravity from a creek and for free, have a filter in the garage and another one under my counter and that's it...... being doing it for seven years and I never being sick.

Have also a 3,500 and a 550 gallons tanks just in case there is a nuclear or gas attack and the open water becomes no good... have a line going from the big tank to my underground bunker.

When I go for a walk up in the hills I carry my straw water filter.

Off the top of my head, I cant think of a bacteria in stockpiled water that makes a toxin such as you describe/fear.

If it were common, I would imagine you would hear about it.

Botulism dies when cooked to 240ºF/116ºC, or boiled for 10 minutes.
Salmonella dies at 160ºF/71ºC.
E.coli dies at 160º/F/71ºC.
Typhoid dies when boiled.

Boiling takes place at 212ºF/100ºC

But if the water was bleached and not opened, how would contamination occur? There is no such thing as spontaneous generation.

Sue