I don't know as I would give up using chlorine bleach entirely.

I suspect that a good part of the corrosion issue comes from simple overuse. I've pitted my share of stainless steel pans and silverware using bleach too enthusiastically. It is easy to splash in some bleach and wing the concentration. The shift from 'regular' to 'ultra' bleach over the last few years has made overuse still easier.

The standard concentration of bleach to water to disinfect surfaces is one in ten. This is what is used for disinfecting surfaces contaminated by HIV, Hep-C, flu, you-name-it. Higher concentrations are Not more effective nor do they work any faster. Most people use far higher concentrations of bleach than necessary.

But remember that bleach is a good disinfectant but a lousy cleaner. For the best bacteriological safety you want to clean, scrub with soap and water to remove the bulk crud, and follow up by disinfecting with a bleach solution.

The action of copper inducing corrosion on aluminum is primarily a saltwater issue because the saltwater is both conductive and corrosive on its own but galvanic corrosion can cause some pitting of aluminum in fresh water. Same mechanism and effect but much more slowly.

In saltwater just scraping the aluminum with copper, transferring tiny bits of copper, can be enough to cause a reaction. Doing electrical work on a boat, particularly an aluminum hulled boat, it is wise to police all wire cut-offs. A lot of mechanics spread out and work on top of a piece of canvas. This keeps waste under control, and keeps dropped tools from falling into the bilge.

If the goal is an actual hole saltwater and a solid copper penny, as opposed to the more modern copper plated zinc, are the optimum ingredients for success.

If you wish to observe this effect it is simple enough to mix up some saltwater in an aluminum soda can and drop in a pre-1982, solid copper, penny. Clean the penny, slightly scratching the aluminum, and increasing the heat all speed the process. This is a fun experiment for kids.

Technically you can drop down to 11% chrome and still be considered "stainless steel". The chrome on the surface of the stainless steel item reacts instantly with any oxygen present to form chrome oxide. The chrome oxide forms a protective layer over the surface of the steel which prevents oxygen from reacting with the iron to create iron oxide aka rust.

The problem with bleach (and salt water) is that it contains chloride ions. Chlorine LOVES to react with chrome, so much that it will even tear it away from oxygen. Chloride ions yank chrome from the chrome oxide, causing holes in the protective layer and prevent a new chrome oxide layer from forming. This leaves the remaining iron unprotected and easily corroded. Even weak concentrations of bleach can cause pitting in stainless steel very quickly.

-Blast

I know bleach kills SS thermoses real fast. Usually they don't even look ruined but all it takes is one tiny pinhole on the inside and the vacuum is gone.

@chickenlittle: Good point about thermoses. I hadn't thought of that. Note to self: no bleach allowed in the Nissan.

@Art in Fl: Generally, I'm not going to give up using chlorine bleach. There are too many situations where the "big nuke" is absolutely necessary. But I'll keep a closer eye on concentration and duration. Especially important since I'm seeing household bleach with concentrations ranging from 4% - 6% on the shelf, so it's really important to do the math.

Rather than use Hypochlorites, you could sterilize the stainless steel using sodium hydroxide, i.e. a weak hot solution of caustic soda, then thoroughly clean out with hot boiling water after pouring away the caustic soda solution down the drain.

You could also give the internal stainless steel of a vacuum flask or water bottle etc a couple of blasts with a Steripen just to make sure. This will kill (deactivate) all viruses and bacteria and other nasties such as crypto etc.

...or you could expose the container to the radiation from a low yield nuclear device...with all due respect, and while I enjoy listening to the agonal screams of creatively killed bacteria as much as the next fellow, I spend most of my life eating and drinking out of vessels that have been adequately cleansed with warm soapy water, and seem none the worse for wear. The extreme sterilization methods may pose more hazard to the user's health than do the microbes in the bottle.

Cheap materials from China have been known to contain other
impurities including lead. Those switching from plastic to
metal food and water containers?
It is not called stain-proof, but stain-less.

I'm glad I didn't mention the Nitric Acid or the Iodine solution. The alkali solution such as Caustic soda is much more readily available and is a useful household chemical.

http://www.totalcleaningsupplies.co.uk/caustic-soda-granules---500g-199-p.asp

Caustic soda is no more extreme than using Bleach and is probably safer due to possible reaction with other chemicals that could free Chlorine gas (now that is pretty toxic).

The Steripen is also a quick and simple method of killing bugs rather than a chemical solution and would be a very safe way of disinfecting a water bottle or Vacuum flask without causing any chemical or corrosive actions on the Stainless steel. There is no need for radionuclide energy decontamination as this could prove to be quite dangerous and counter productive especially if your water bottle is contaminated with the Andromeda Strain

The steripen approach-bathing the inside of the bottle in synthetic sunshine-is delightful and non-toxic. I must concede that the boiling caustic soda solution would be very useful if the water bottle contained bacteria-contaminated oysters, or a small, rabid wolverine. I suppose one must identify the contaminant in order to make sense of the cleansing process.

I agree.

A simple soap and water wash and air frying covers 90% of the cleaning and disinfection needs in every day use. If there is contamination by blood or body fluids, or diseases going around disinfection with a 10% bleach solution after cleaning covers that.

Alternatives that are known to work, efficacy depends on the specifics of what is being cleaned and what it is contaminated with: laying stuff out in direct sunlight, boiling water, immersing objects in water double dosed with iodine water purification tablets, steaming, heating stuff in/near the campfire, alcohol wash, dehydration/aging.