Once you find water, a major issue remains: is it pure? Is it drinkable? And if not, how to make it drinkable?
In today’s world this is a much more complex issue than it was previously. Just 20 years ago in Canada you could still drink water from the streams, rivers, and lakes in the north — for example, in northern Ontario, including northern Lake Huron and the Bruce Peninsula. However, the spread of Giardia in recent years has greatly increased the risk of drinking water straight from these sources.
Giardia is a non-native organism (actually a cyst) that can seriously debilitate you if you get it. It infects your digestive tract. The primary way it spreads is through the droppings of beaver. However, recent research has suggested that other animals spread it as well.
Additionally, industrial and chemical pollutants are probably more widespread than they were in previous years. Certainly they are more widespread than 50 years ago. And this in spite of increased awareness of the dangers of these!
One important point to remember: segregate the containers you use. Always use a different container for impure water from the container you store purified water in. Never mix the functions of the two types of containers. That is, never store impure water in the container that you are using for purified water, and vice versa.
Assessing water purity
Bacterial and similar agents
silt and suspended materials
modern-day pollutants (chemicals, heavy metals, etc)
ASSESSING WATER PURITY
Here are some general rules for water purity. Please bear in mind that these are general rules only. Every situation must be assessed on its own. This section does NOT take into account pollutants (see next section).
Running water is generally better than still water.
Water coming out of the ground from a spring is generally more pure than water that has been running over the ground
Look for clear water
Avoid water that has algae growing in it
Avoid discoloured water
Avoid water in marshes and swamps
via Water Purification.