But it is not safe to eat canned food that has been tainted no matter how much or how long you cook it. The organisms may die but the toxins they produced remain. I'm just wondering if the same critters eventually show up in water.

The trailer water tank is by no means a sealed system. I agree that it is unlikely to get contaminated in such a short amount of time, but it could happen. Although I store drinking water seperately, I'd like to have the extra 40 gallons for backup. Right now I'm planning on using it primarily for sanitation.

Heck, where I come from we call that soup.

I can't think of anything that will flourish in the conditions you describe that wouldn't be taken care of by boiling. Toxins must be created by some organism, but if the organism itself can't start growing first, there's no risk of ingesting the toxin.

But you do mention algae. I don't have any experience with RV's or trailers, but can you actually get algae growth in the water tanks when maintained properly? I would think it would require sunlight to encourage algae growth.

I think you and the others are probably right. Bleach + Boiling should do the job. As far as algae goes, the water tank on the trailer does receive indirect sunlight, but it will probably take more than 3 months to take hold. I guess I'll find out later this summer.

I guess my initial concern is that, if the water has been properly treated and maintained, and there's still the likelihood of algael growth thereafter, then the water is not secured, and is being contaminated somehow. That being the case, where one lifeform can grow, so can others.

If, however, the water is secured such that no algae are present despite the presense of sunlight, then it is likely nothing else made it through the processing cycle that would somehow have survived. In addition to the algae, I would be looking for suspended 'floaties' in the water before consuming it as well.

High levels of UV and Ion Exchange mechanisms will breakdown all organic components in water, whether organisms, or by-products or organisms. You hit it with enough juice, it will render anything organic inert. Heat ain't the only way to get rid of it.

The Botulinum toxins (two-chain polypeptide with a 100-kDa heavy chain joined by a disulphide bond to a 50-kDa light chain, which is an active enzyme) produced by Botulinum spores can be destroyed by boiling the water. The Botulium spores though can still present a danger as they are more heat tolerant. I would suggest the following procedure to deal with any contamination. Firstly filter the water with a suitable commercial ceramic based submicron filter such as Katadyn Pocket Water Microfilter (this will take care of most bacteria) then boil the water for 10 minutes, rolling boil or to be really sure, use an old fashioned pressure cooker (will raise water temperature higher than 100 degrees Celsius), allow to cool, then give it a blast with a Steripen (should deal with anything that has any DNA that has not already been destroyed by heat treatment). Then whisk the water thoroughly to add some oxygen to improve the taste. To improve the flavor of the water so that it is potable a chemical after taste tablet could also be added. This should deal with any non-chemical contamination.

I don't think normal algae is harmful, with the exception of blue-green algae, which isn't a true algae but a bacteria, and that red-tide stuff that poisons shellfish, etc. To get regular algae, I'm pretty sure that most kinds have to be exposed to light, not warmth. And a lot of algae is caused by excess nutrients in the water.

From what I understand, water in a container isn't too much of a likely source of botulism.

Some excerpts from the Center for Disease Control (CDC) regarding botulism:

"Clostridium botulinum is... a group of bacteria commonly found in soil. These... organisms grow best in low oxygen conditions.

"In the United States an average of 110 cases of botulism are reported each year. Of these, approximately 25% are foodborne, 72% are infant botulism, and the rest are wound botulism... wound botulism has increased because of the use of black-tar heroin, especially in California.

"Foodborne botulism has often been from home-canned foods with low acid content, such as asparagus, green beans, beets and corn. However, outbreaks of botulism from more unusual sources such as chopped garlic in oil, chile peppers, tomatoes, improperly handled baked potatoes wrapped in aluminum foil, and home-canned or fermented fish.

For more info, see http://www.cdc.gov/ncidod/dbmd/diseaseinfo/botulism_g.htm

I could be wrong here, but seems to me that if algae and critters (i.e. water skippers, mosquito larvae etc.) are actively living in the water thats a pretty good indicator the water is safe after some purification.

If they are closed containers that were prepped before closing (Chlorine added) I can't imagine too much stuff growing in them during storage.

You only have to heat the water to a point to break down the protiens for the microbs or their by products, which are protiens. This is 160 to 180 degrees F. You do not have to boil it for 10 minutes but simply bring it to the point where bubbles start to form. And even on the top of Mt Everst this will be about 160 degrees F. If the water is stored and sealed then there should be NO question of the waters quality.
cheers