No doubt there are lots of options for water storage in vehicles. That's a good thing.

I'm not a rich man, but I find <$3/year pretty darn cheap actually to be free from concern of having water go bad, leak, forgetting to rotate or restock, etc. Especially so for family members where "set and forget preparation" is the best one can hope for.

Your mileage may vary of course... and that's just fine.



((Before someone asks since it seems important to the discussion: Case of Datrex/Mayday/et al is around $24. Split between two vehicles and over 4 years let's say... 24 /2 = 12 /4 = $3 per vehicle per year ))

One thing to keep in mind - "Any water is better than no water." I started fairly serious outdoor trips in SE Arizona some years ago, and I soon adopted the notion that however sick this water makes me, by the time that happens I will at least be able to return to town where I can be cured. This has worked just fine for me in the back country - industrial waste situations closer to civilization might be somewhat different.

Indifferent water can be boiled and that will take care of the pathogens, although it won't deal with toxins, etc. I have boiled for years and never regretted doing so.

Yes, psychology often trumps all other considerations and if "bag water" is strange enough to be left alone wherever its stored then mission accomplished

Yes, extreme pain in the wallet for poor comparison shoppers

Also, think about the kinds of water rations that inspired the USCG standard in the first place The water either leaked away or turned to rust soup or worse, eew

Also, the way I understand concerns with leaching , they are about chronic/pervasive/cumulative exposure, resulting in an increased risk of "something", ie an everyday/lifetime concern, not an emergency concern

The way I figure, restocking a commercial kit, for a business, I'm going with USCG water

If i'm making a car kit, its bottled water, powdered drink mix for super sensitive tasters, maybe rotate once a year at the end of summer ...

• Don’t drink the (warm) water left in a plastic bottle, UF/IFAS study says | IFAS News
  
  Originally Posted By: https://news.ifas.ufl.edu/2014/09/dont-drink-the-warm-water-ufifas-study-says/

  UF soil and water science professor Lena Ma led a research team that studied chemicals released in 16 brands of bottled water kept at 158 degrees Fahrenheit for four weeks, what researchers deemed a “worst-case scenario” for human consumption.
  The UF scientist warned against leaving bottled water in a hot garage for weeks on end or in your car all day during the summer.
• A Spring Spent Inside A Car Trunk: Tracking Temperature for 3 Months in the Midwest
• 16470261 Contamination of Canadian and European bottled waters with antimony from PET containers. - PubMed - NCBI
• PMC4245802 Effects of storage time and temperature on the antimony and some trace element release from polyethylene terephthalate (PET) into the bottled drinking water
• ucm077079 Buy, Store & Serve Safe Food > February/March 2002 Ask the Regulators -- Bottled Water Regulation and the FDA
• PMC3222987 Most Plastic Products Release Estrogenic Chemicals: A Potential Health Problem That Can Be Solved
  Percentage of unstressed plastic products having detectable EA (> 15% RME2) in two extracts.
• Post175260] Hmm, 256 nanograms equals 0.000256mg, so someone would need to drink 5859.4 liters of BPA-contaiminated water per kilogram of their weight daily for nine months to suffer these effects. -Blast, Ph.D.
• tetrapak.pdf Aseptic packages are made of several laminated layers, including paper, aluminum and low-density polyethylene.
• More Trunk Temperature Data
• Study: Car Interiors Reach Dangerous Temps All Year - Story
• PMC4245802 Effects of storage time and temperature on the antimony and some trace element release from polyethylene terephthalate (PET) into the bottled drinking water
  
  Originally Posted By: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4245802/

  
  Antimony concentration was the main concern in our study. The concentrations increased in each of the sample during storage period at all temperatures. The results for different conditions were as follow: at 40°C, in outdoor and at room temperature the Sb concentrations were below the MCLs, i e. 6 ppb. However, at 65°C and 80°C for longer storage times Sb concentration exceeded the MCLs, and variations between the samples were significant (p?=?0.05). Storage time and temperature effects on the content of some other trace elements such as Al, Fe were also significant (p?=?0.05).
  Conclusion
  By increasing the duration of storage time and temperatures, antimony leaching from the PET bottles into the bottled water increased. The concentration of Al demonstrated an increase in higher temperatures and storage duration, whereas the content of Fe demonstrated no significant differences.
  Last of all, the consumer should not leave the bottled waters inside their vehicles’ and/or closed areas due to the high temperatures which occur in these conditions.
  The five storage conditions designed for the investigation of the samples were, storage at room temperature (25?±?2.6°C), outdoors and sunlight (31?±?4.6°C) and 40°C and the experiment intervals were defined as follows, weeks 0 (immediately after receiving), 1, 2, 4, 6 and 8 were performed. Storage at 65°C, and the experiments was done in days zero (immediately after receiving), 3, 7 and weeks 2, 4 and 6. Storage at 80°C at test days zero (immediately after receiving), 1, 2, 3, 4 and 7 was considered for the other storage condition.
  
  
  40 celsius is 104 farenheit, 65 is 149, and 80 is 176
• trihalomethanes / chlorine Disinfection By-Products
• Emergency rations for storage in a car? - ETS Forums
• How much hotter is a black car than a white car in the sun?
• S095671351200299X Temperature increase of foods in car trunk and the potential hazard for microbial growth

This is truly an impressive compilation of research. Superficially, it would appear that one of potential problems involves the use of PET bottles as containers, unrelated to the water itself. Would you be better off by storing tap water in a stainless steel container?

Yeah, plastic bottles may make the water iffy after a time. How well does a typical water filter such as the MSR MiniWorks remove the unwanted chemicals? Having water in your truck that's tainted isn't a great idea and having a filter alone only works if there is a source of water somewhere. Having tainted water and a filter to untaint it may be a viable solution.

Yeah, I have the filter above in my truck too

Ceramic or carbon filters cannot remove inorganic stuff from the water, e.g. the mentioned in the above studies Antimony molecule size is several millions times smaller in diameter than a typical Cryptosporidium, which is the smallest particle these filters can stop. You need a distillator or a reverse osmosis filter.

On other hand, I don't see any problem drinking water contaminated with chemicals from a PET or any other food grade bottles in an emergency. The adverse effect will be seen only if you're doing that on a regular basis for years.

Kinda sort
Sure ,
stainless steel won't leach BPA/EA/Estrongenic
or lead/antimony ( as long as it isn't brazed),
...
so stainless steel is "better" naturally,
but is the difference important?
I don't think so

Blast puts it in perspective, you'd need to drink 5859.4 liters of BPA-contaiminated water per kilogram of their weight daily for nine months to suffer these effects. -Blast, Ph.D.

So, you're storing your platic bottled water,
in deadly heat (100 Fahrenheit and above)
and sunshine for more than 8 weeks,
the leaching worst case results in exceeding the Maximum Contaminant Level (MCL) of 0.006 mg/L by 30 times,
well all that means is after you deploy that drinking water in an emergency,
cut out the bottled water for the month after

Also consider this old data point Antimony Toxicity The average intake of antimony from food and water was estimated to be roughly 5 µg/day ( 0.005 mg )
which is just under the drinking water MCL of 0.006 mg/L
compared to the tolerable daily intake (TDI) of 0.006 mg/kg bodyweight/day

Somewhere it also said most of this exposure comes from plumbing
the more acute exposure is from work where OSHA should protect you
... or self-poisoning from folk medicine

If you have a physical or blood test coming up,
ask your doctor/technician about your lead/antimony... levels

My family drinks lots of bottled water (1-3 0.5L bottles daily),
even the "baby",
often stored outside in sfbayarea sunshine,
or in hot garage (not as hot as car/trunk),
or room temperature (avg 72, never more than 82 )
... there have been no reports of elevated antimony/lead levels from our docs

I have water in the trunk that's at least 5 years old, I'd still drink it
It tastes better after all this time than regular non-filtered tap water ,
which tastes disgusting like most tap water,
but I'd still drink that too in everyday non-emergency situation
Some family members are less willing to compromise when it comes to taste
and after many many years I'm getting there too ...
this just means tea tea

Regular household pitcher/faucet/refrigerator filters, will reduce levels of lead... and improve taste

A quick peek at Consumers Reports Online revealed this tidbit:

"Bottled water, often advertised as a "pure" and "natural" alternative to tap water, is generally safe. But it's actually less regulated by the Environmental Protection Agency than municipal water supplies. Indeed, some bottled water is simply filtered tap water."

I believe they ran a double blind water tasting trial a few years ago, and Los Angeles tap water was the winner, preferred over all the bottled waters that were tested.

Taste in water leaves me puzzled - the primary sensation for me on drinking water is wetness and liquidity, the result of a long time in desert environments, and it helps that my taste buds were shot off in the war.