Many people feel uncomfortable drinking water from the tap in their homes, schools, and businesses. Some studies have shown that tap water is harmful to health because contaminants can enter the water system. Some of these contaminants include those from pesticides, metals like lead and mercury, and other industrial sources. In addition to purifying water from these harmful contaminants, water purifiers eliminate foul odors, cloudiness, and discoloration in the water. Foul odors can be caused by chlorine, while cloudiness is caused by deposits from rocks in the form of sediment.