In my experience stored tap water is very safe. It gets stale and flat. I've had some strange grassy tastes show up, mostly what I assume to be algae, but the water caused no ill effects even after several years storage in less than ideal conditions. Worse case any water with an off taste can be used cooking or washing.

Given that major disease causing organisms are not in the tap water when it is stored it can, IMO, be safely assumed they won't be in water stored for long periods. There will always be some amount of bacteria and algae in the water because it is in the air but my tap water isn't nutrient-rich enough to support more than minimal growth.

That said changing out the water every year doesn't seem an unreasonable burden. And tap water, at pennies per thousand gallons, is a whole lot less expensive than commercial bottled water.

I rotate out the stored water every 2-3 months. Our tap water is usually not chlorinated. I would still consider the water fine after 6 months or so, but other members of the household are dubious about drinking it when it has been stored that long, so I change it more often than that and note the date on stick on labels at the time. Half the supply is stored in a large cooler (one of those tough ones with wheels that you can sit on). This keeps it out of the light and I reckon that even if the house fell on it the darn thing would survice.
I've got a mixture of recycled soda bottles and white plastic food grade bottles. Nothing above 5 liters as I have too much trouble lifting them when changing the water.

Check this out for emergency water storage.

http://mywatersafe.com/

I want a bathtub watersafe!!! To bad my tap water is garbage Darn you untreated well water!

The trouble with the larger water bladders such as the "Watersafe" is the prevention of bacteria and mold growth in the bladder after you use it.

Sure you could attempt to completely dry the bladder somehow or treat it by adding bleach or chlorine to the bag before emptying out as much water as possible. However once the small remaining amount of bleach or chlorine looses it's effectiveness after a few weeks, the confines of the bladder are the perfect bacteria and mold breeding environment which would be difficult, if not impossible to eradicate afterwards.

The WaterBOB is cheaper at $25, and it does say it is 10 mil, the WateSafe doesn't say.

Keep in mind that these are single-use because once filled, they can't be dried out inside, and will eventually mold.

Sue

What about installing a large plastic tank in-line with your water supply. Say 100 gals or so. This takes out the effort of having to manually rotate your water in containers. Mount it relatively high on concrete blocks so it can gravity feed your water heater. Thus you would have the water STORED in the water heater and the water stored in the tank. An extra spigot at the bottom of the tank would allow for easy drainage into smaller containers. Since the tank would be in-line, the water would never be stale.

flush your hot water heater every year or so to make sure that sediment has not blocked the bottom drain... this is very easy to forget or overlook...my house is an old Fla frame house about 2ft off the ground, so a short piece of old garden hose works fine... gives me an additional 50gallons I've never had to use

Water, as long as it is relatively pure, doesn't really go bad if well stored. People have used cisterns for water storage for thousands of years. Even minor contamination with small amounts of every day crud and dirt tends to be self-correcting as long as oxygen is present and light is limited. While it is best to keep insects and debris out a few leaves or insects are going to be consumed, their nutrients used up and broken down, and the resulting simpler material settles out.

In traditional English plumbing water pressure for the house was maintained by a cistern on the roof or in the attic. This saved wear and tear on the pumps and the need for complicated pressure valves. The cisterns were supposed to be covered loosely and screened. According to literature finding a dead rat, and/or a bird or two, in the cistern was pretty common. Funky as that sounds it was quite rare for anyone to get sick. Of course, being English, they usually took their water in the form of tea or whiskey. Safety from both ends.

In a well maintained cistern, one that excludes the rats and birds, small amounts of bacterial algae and spores are still pretty much impossible to keep out because they come in on the air. If the water they land in doesn't have enough food they die out. If it does, they multiply until they consume the available food supply, and then die out. Their tiny corpses settle to the bottom where they are removed in the regular bottom cleaning that is scheduled ever year or three.

Thanks everyone! I had a "Duh!" moment today. While reading through your insights, a couple of lightbulbs turned on.

First - why not store tap water in all our water carriers? We've got a few of the big blue cubes and a gazillion nagalene and stainless water bottles stored in the house and garage. They might as well be in use at the same time as they're sitting collecting dust.

Then a second lightbulb - why not make use of all the potential carriers that come into the house as well? All the bottles with resealable lids are perfect candidates. pop, juice, wine and liquor bottles with screw-top lids are now going to be diverted from the recycling bin.

Good prep for us and good for the earth. So simple! I feel like a dope for not thinking about it sooner and wasting all that money buying bottled water. Duh!