If you source your water from a bore, tank, lake, dam or water ways then this water flows through areas that contain micro-organisms. If the conditions are right then the type micro-organisms that get into your water supply might be the type that makes you ill. It only takes the right environmental conditions then your water will be contaminated. For example Leptospirosis is a bacteria that is found in rats and mice faeces. When the faeces are washed into your water supply it has caused people to die.
Great Water Filters markets the Elite Series 4 UV Light Under Sink Water Filter that will protect you and your family against the dangers of germs. You can upgrade any of the Elite Series to have a UV light filter. The Elite Series 5 Whole House Water Filter System offers an upgrade that will be especially beneficial if you source your water from an untreated supply. Ultra Violet Light water treatment comes highly recommended.