Why does the water have to be purified?

Because there are many potential impurities in our drinking water and you don't want to ingest them. They can cause serious health problems like cancer, etc. The best way to ensure you have good, clean water is to get a drinking water filtration system that works on a carbon block like www.mosteffectivefilter.com. These type of filters help to reduce the toxins or chemicals that can be dangerous to our health.