Why the Quality of drinkng water is deteriorating?

Our water sources are increasingly getting polluted. As a result the water we get is full of impurities and not fit for drinking.River water, which is our primary source of water, gets contaminated due to various reasons such as direct disposal of sewage by municipalities, excessive discharge of industrial pollutants, use for daily chores like washing, bathing, livestock bathing, garbage disposal, etc.
Water sourced from groundwater too has deteriorated due to the excessive use of pesticides & insecticides in agriculture, which seep into the groundwater as well as get washed away into the rivers. Decreasing levels of groundwater also attracts natural contaminants present in the earth such as Arsenic, Fluoride, Lead, Heavy Metals, which make the water hard.