Generally non-portable water is not treated or has any purification. Well water is a good example where water taken from a bore hole on a farm is used for irrigation and not for drinking.
Drinking water has had treatment to remove any pathogens that may exist in the water that is drawn from a bore hole. Bacteria can live in extreme conditions and if is well known that bacteria can live in water, so drinking water will be treated to minimise the risk of these water borne pathogens from being able to spread though a drinking water system.
You can treat non-portable water with water purification systems and filtering systems.
Bottled water is not necessarily pure or better than tap water from a country that produces potable water as a standard. It is a myth that bottle water is better for you, therefore it is always best if you're not sure, to buy bottled water that is certified as treated for drinking.
If in doubt use water purification tablets.
