Why should Survivalist worry about water filters? Because when the city water supply stops, the water in the local lakes and streams may not be safe to drink. Most survivalist have stockpiled water, and that is fine – there is nothing wrong with stockpiling water. But you need some kind of solution for after your stockpiles of water run out. A lot of people might say “I’ll just dig a well if I need water” – ok, lets get back to reality. Most of people are not going to dig a well overnight.
Here is short list of waterborne diseases and parasites: