If you come to find yourself in a situation where you do not have water or where what water you have is contaminated you have a few options. First and foremost there should be no reason why you can not have some water stored in your home, water is cheap and can store for a very long time we also take it for granted too often. Many people will re-use 2 liter bottles, 5 gallon water cooler jugs or one of my favorites a 1gallon Arizona Iced tea jug because they are a heavy plastic. I know some people use old 1 gallon milk jugs but I try to stay away from them as they are very light weight and have a questionable cap.
The above option works well for a short term problem if you are at home and have a supply already in place ahead of time, there are other sources of water available in your home but that is a mini article itself. Now if you have the other problem of having water but it is contaminated or even if you think it is contaminated you have a few solutions to that problem as well. I am sure that every has at some point in time been under a " Boil Order" this is usually due to a pipe being broken underground during some type of construction. A boil order means that they want you to do just that, boil the water you will be using for internal consumption, cooking and cleaning. The amount of time to boil the water is up for debate and I have seen it stated that once it is boiling it is good and I have also seen it recommended to let it boil for 10 minutes, as for me I usually go 5 minutes and call it dead, dead for the micro-organisms that is. Do keep in mind though that this is hot boiling water, that will scald you so be careful. The one biggest issue wilt boiling water though is the fuel you need to do it with, if you are at home and the power or gas is on then you are OK. Other options you could use in a pinch are your outside gas grill or if you have electricity but your stove is gas and that is out you can use your microwave. Other option's would be if you had a wood burning stove or a fireplace, If you are camping then you have your campfire for a heat source for boiling.
Newer options have come to us to purify water in the form of high tech filters and ultraviolet sterilization pens. There are many more ways to sterilize water that are not mentioned here, punch up your favorite search engine and do a little research as there are many choices and sizes to pick from. Below are a few of the larger players in the field.