Here is a very useful and informative article I recently read on zombease.com website. The link is list here:
Finding, Collecting, and Treating for Survival such as a Zombie Outbreak or major earthquake, local water sources may become tainted, unavailable, or inaccessible. City waterworks may be damaged and stop pumping the precious fluid to our homes, businesses, parks, etc. But even if the water supply becomes tainted or is difficult to access, with a little care and patience you can collect enough to survive and use it safely.
Accessing water might not be as simple as turning on a tap, but you’d be surprised at the number of locations you can find it, if you take the time to look.
Rural Areas: Homes in rural areas often have wells or creeks on or near their property, giving them easy-to-access and likely safe water supplies. Other water sources in rural areas include, but are not limited to: watering troughs, silos, rain collection barrels, and man-made or naturally occurring ponds.
Urban Areas: There are plenty of places to collect water from in the city, even if the local waterworks have been shut off. Hoses, rain barrels, buckets, natural water sources, public fountains, old tires, water heaters, and toilet tanks are just a few of the many places water may be hiding out in an urban environment.
Wherever and whenever you might be looking for water it’s important to keep your eyes open and be creative. Next time you’re out and about, take a look around you and see if you can spot at least two alternate sources for a bit of the wet stuff. And remember that you must filter and purify ALL found water before consumption.
The most basic method for collecting water comes in the form of transfer from one source or container to another. This can be done a number of ways, but typically the use of a bucket or other pail-like device is recommended. You should never siphon water with your mouth and a hose from an unfiltered or untreated source, you are just as likely to become ill by doing this, as you are by direct and intentional consumption. Using a pump siphon to transfer water for treatment later is a fantastic and relatively easy way to move large amounts of water fast.
Always draw from the clearest and cleanest source that you can, and NEVER use water that has inorganic materials floating on the surface, is dark or oddly colored, has any odor at all, or shows any other signs of possible contamination. But if there is just a bit of dirt or sand in the water it should be fine after a little care is taken.
UrbanMan's note: Your survival kit should always contain collapsible expedient water containers.
MAKE IT SAFE TO DRINK:
Unless you want to pay an uncomfortable, and possibly deadly price for drinking even just a few gulps of tainted water, it’s always better to be safe than sorry. All found water, unless from a sealed and reliable source, needs to be both filtered and treated before consumption.
Filter: You will need to remove as much dirt and debris as possible from the water before moving on to the next step. If the water is cloudy it’s best to let it settle naturally over the course of 12 – 24 hours, but you may be in a rush and pouring it through a coffee filter, handkerchief, or other fine material, into a clean container will work as well. Make sure to change and/or clean any filters you use as they begin to show signs of contamination or discoloration.
The water should now be safe to use for washing clothes and gear, but not for drinking, personal care, bathing, or cleaning cookware, you’ve got another step before that.
The use of a well-made commercial filter allows you to skip the next step and go directly to consumption. Incredibly useful and capable of filtering 100s of gallons before the filter needs to be replaced we recommend the Katadyn Hiker Pro for those of you with the available income.
Treatment is a crucial step in the purifying process and should never be skipped. Now that you’ve filtered your water and it isn’t cloudy anymore, you’ll need to kill any germs left-over that may be in the water. Treatment by boiling or with bleach are the most widely agreed upon methods to safely purify questionable water, and luckily you only have to do one or the other before it’s safe to drink.
Boiling: Evaporation during boiling can be a problem if you don’t have a covered container, and the need for fuel can make this a tricky task for some. But while this method has it’s drawbacks, it remains highly effective when done properly.
All questionable water should be boiled for no less that 3 – 5 minutes for proper sanitation, but a period of 10 minutes is the best way to guarantee safe consumption (because boiling water at high altitudes takes longer, you need to add 1 minute of boil time for every 1000 feet above sea level that you are located). After the water is done boiling, it’s important to let it cool before taking a drink.
Boil treated water can safely be stored in clean and resealable containers for up to one year.
Bleach: A highly effective method, though dangerous if not done properly, bleach is a wonderful tool for treating questionable water. Use plain liquid bleach with no additives or additional ingredients. Never use scented, color safe, powdered, or boosted bleaches when treating water.
To treat water with chlorine bleach, simply place the water into a clean container and add exactly 16 drops for every gallon of water (this is most easily done with an eye-dropper). Stir the mixture well and let it rest for 30 minutes. If the water does not retain a slight bleach smell, repeat the addition of drops per gallon and let it rest for another 15 minutes. If it still does not retain a slight bleach smell, the water is too highly contaminated and will not be usable. At this point, it’s time to get a new batch of water and try again.
•1 quart bottle 4 drops of bleach
•2 liter soda bottle 10 drops of bleach
•1 gallon jug 16 drops of bleach (1/8 tsp)
•2 gallon cooler 32 drops of bleach (1/4 tsp)
•5 gallon bottle 1 teaspoon of bleach
Bleach treated water can safely be stored in clean and resealable containers for up to one year.