How Long Does Potable Water Keep

[hellosailor]

Bob, you've got to put the bottle dates in context. I don't think they are "government" dates or any other type of mandated dates. Last I heard, they were put there by the bottler, as their own opinion and motivation for you to replace them and use them by that date.

I found an overlooked bottle of mustard in the back of a shelf. I won't tell you how far past the "USE BY" date it was but "several years" comes to mind. Except, vinegar is a great preservative and the mustard still tasted fine. No, I wouldn't do that with most foods. I was looking all the way in back because a tin of condensed milk pinholed and died. Well before the expiry date.

[Celestialsailor]

Another point here should be water tanks in the boat. As mentioned, water is only as good as the storage point. I have not taken my inspection port off my 74 gallon bilge tank yet but it's on the short list. They should be opened, bleached out and resealed with new hoses from time to time. Generally I add 1/2 ounce of bleach to 50 gallons and then filter through an active carbon filter changed every 3-6 months.

[Roy M]

I am about to overhaul my water system. The new one will have a pair of 20-30 gallon polyethylene tanks to divide the supply. The watermaker (Spectra) will feed one at a time, in case of a problem. The water from the tanks will then be passed, at the faucet end, through a particulate and carbon filter, and a UV lamp unit. I'd like to install a particulate filter at the air vents to reduce the entry of airborne buggies. I'll also have a stash of one gallon bottles for emergency use, plus I'll freeze some to keep me in cold water for the Sodastream and other cooling beverages. If I don't have to take to a liferaft, I should have plenty of water in an emergency for all aboard.

[DumnMad]

Some bottled spring water in NZ has been carbon dated as 1800 years old since it fell as rain. Just sayin.

[Rakuflames]

Originally Posted by cburger

Was as a club function this weekend speaking with a gentleman who seems like a very knowledgeable guy/ scientist/ sailor. At one point the discussion turned to water storage and he made the statement to me that drinking water should only be stored for a very short period of time before it starts to become usable, a couple of weeks.

I had always thought water can be stored almost indefinatly remember seeing all the drums of water in fallout shelters in the U.S that had been there for years, as well as all the municipal storage tanks that I don't think get used and replenished every couple of weeks.

So the question is how long does drinking water keep in tanks on a boat before it should be changed?

The problem is that it isn't possible to sterilize the tank, and it isn't possible to sterilize the water. Treating with chlorine will get *most* things but not everything, and then you have an ideal climate for ... growing things.

Personally I never drink the water from my tank, and I know other people who are medical professionals who say the same thing. Others may disagree of course; that's just my opinion. But I have had my water go foul once and it was ... well ... foul.

[1affiah]

As in most things, there is a shred of truth to most of the comments about the shelf life of water, but as a member of the municipal water supply industry, I can tell you with absolute certainly that the disinfectant chemicals used in the public water supply will deteriorate after a few weeks, then become toxic. How soon will depend on the temperature, exposure to light, etc.

Google the American Water Works Association (AWWA) and search for water quality issues evident in every American city, it's all about continuous monitoring, flushing and sampling.

My guess is that water packed expressly for storage, such as in life rafts, etc., is sterilized, not disenfected with chlorine, then packed into sterile containers, similar to sterilized milk.

My advice is to fill your tanks from a muni supply only after running the supply hose long enough to assure fresh water from the mains, and consider a charcoal filter in the boat supply lines. We dump all the water from our system every time we leave the boat, and refill with fresh when we return.

Larry

[Snore]

Originally Posted by 1affiah

As in most things, there is a shred of truth to most of the comments about the shelf life of water..... I can tell you with absolute certainly that the disinfectant chemicals used in the public water supply will deteriorate after a few weeks, then become toxic.

Gee could you tell us how 30-50 or even 100 gallons of water disinfected with chloramines can become toxic?

[1affiah]

No, I can't. I'm not a chemist, and there are many variables. My only point in posting was to inform that the disenfectants in the public water supply, which do include commonly used chlorine, can and do turn toxic over time, which is why there exisit guidelines for flushing stangnant, treated water.

Best Practices: Complying With the Stage 2 D/DBP Rule - Opflow - Publications - AWWA

This is an article addressing the issue to water industry professionals.
You will need to join the organization and sign in to view it.

Cheers!
Larry

[jannw]

according to the arseholes who re-did my liferaft, water in bottles lasts 2 years, but costs 12 euros per liter to replace ... YMMV ... But it is the last time I get my liferaft serviced professionally!

[Snore]

Originally Posted by 1affiah

No, I can't. I'm not a chemist, and there are many variables. My only point in posting was to inform that the disenfectants in the public water supply, which do include commonly used chlorine, can and do turn toxic over time,


Cheers!
Larry

Larry

I belong to AWWA and am state licensed. Without taking this thread miles off target, there are material defects in your statements. For example chlorine or now chloramines have been used for over 90 years in drinking water. The disinfectant does not become toxic, but if a plethora of conditions are right some disinfectant by-products may form over time.


Bill

[S/V Illusion]

Originally Posted by Snore

Gee could you tell us how 30-50 or even 100 gallons of water disinfected with chloramines can become toxic?

Chloramines have not been thoroughly studied for their health effects. Chlorine is the only disinfectant that has been extensively studied. Some chloramines are toxic and more so when combined with some organics which could be present in water tanks. Suffice it to say, as I did way back in this thread, that the best anyone could hope for with disinfection is a temporary affect with no guarantee of sustained disinfection. Consequently, if you use tank water for anything other than washing the boat, you are taking a chance and no common filter will change that fact.

[Snore]

We will agree to disagree, no need for head banging, grinding of teeth or pulling your hair.

The following link provides some good facts regarding chloramines http://water.epa.gov/lawsregs/rulesr...ines_index.cfm In summary the reports show that when maximum levels are exceeded their may be health effects. But that is why they are MAXimums.

With that I will bow out of this thread.

Bill

[svBeBe]

Bottled water has a shelf life not because the water itself goes bad, but because of the plastic in which it is stored. There are many different grades of plastic. Notice how thin is the plastic used for bottles of water. That grade plastic leaches chemicals into the water over time. Hence the expiry date.

Judy

[Sunspot Baby]

Lots of good facts and opinions above. Thanks.

All of this reminds me why we made the decision to install a small water maker just for our consumption, drinking and cooking. Tank water is used for bathing, washing up, etc. However, the dog drinks it and is still doing OK.

George