SO YOU HAVE an emergency supply of water, but you're not sure how pure it is. Here is an excellent, cheap setup you can easily DIY for purifying LOTS of water. It's based on the Berkey ceramic water element filtration system that's been around for a long time. LOOK ON AMAZON FOR "DOULTON" FILTERS. The ceramic material will filter down to .5 micron (that's 1/2 of a millionth of an inch) and according to the manufacturer will eliminate bacteria like E. coli and salmonella, and parasites like Crytposporidium and Giardia, microscopic impurities that will cause serious health problems and even death. A colleague of mine who has a great deal of knowledge in the area of food safety has studied this setup carefully and I have built a system per his recommendations. My primary system has 3 filters and will be used if I need to purify questionable water. From there, you would dispense the water and add 4 drops of non-scented bleach per gallon, let it sit for at least 15 minutes. This will address the possibility that there could be extremely small amounts or particulate matter, for example if you were purifying water from a creek. The bleach will take care of any traces of impurities, then add the bleached water to a 2nd filter system to eliminate the bleach traces. The result SHOULD BE a SAFE source of drinking water.
Worth mentioning is that as long as you are putting in chlorinated tap water from your faucet, you can eliminate purchasing bottled water, because you will have a product that is far better than some of the water out there. AND as long as you are putting in potable water, this system needs almost no maintenance. If you're using tainted water and the impurities clog the elements, they can be removed and scrubbed with a ScotchBrite under some clear running water, and you're back in business. The elements should NEVER need to be replaced. DON'T USE SOAP on the ceramic elements. I use my 3-filter device for drinking water AND for cooking, and it's really nice to have basically free purified water to cook with and not have to worry about a PUR or BRITA filter that just got 1 gallon closer to needing replacement. This setup will pay for itself quickly for most people.
TWO COMPLETE SYSTEMS needs 4 bottles, 4 elements, 2 spigots, and can be made in a couple of hours if you have all the tools located. Cost for the whole thing is about $150, compared to about $700 for 2 of the large stainless steel Berkeys, and I much prefer the transparant bottles so you can see what's going on inside.
I welcome any comments on this critical survival device if anyone sees anything I have missed. This is the method I will be using to purify drinking water for me and my family.
AUTHOR ADDED: I'M GETTING LOTS OF REQUESTS FOR HOW TO FIND THE FILTERS SO I ADDED A SCREEN SHOT OF THE ORDER PAGE FROM WHEN I GOT MINE FROM AMAZON SO YOU CAN SEE HOW MUCH IT COST WITH SHIPPING. I DON'T KNOW THE EXACT PRICES NOW, IT'S LIKELY THE FILTERS ARE GOING UP, BUT EVEN BACK THEN THERE WAS NO SELLER WHO OFFERED ANY BREAKS ON SHIPPING, AT LEAST NONE THAT I COULD FIND.
Here is a link to the manufacturer of the filters: http://doultonusa.com
HERE'S ANOTHER EXCELLENT LINK THAT navarre1095 FOUND:
THE FILTERS THERE HAVE CARBON INSERTS WHICH LASTS A FEW YEARS AT BEST, BUT THE CERAMIC PART IS SIMILAR TO THE DOULTON PRODUCT AND CAN BE CLEANED AND REUSED INDEFINITELY DEPENDING ON THE WATER SOURCE, FOLLOW THE LINK FOR SOME REALLY GOOD INFO, ALSO THEY HAVE A LITTLE BETTER PRICE ON COMPONENTS FOR A SYSTEM LIKE THIS.