Water is vital for life.  We cannot live without water.  However, we cannot use untreated water directly from water source because contaminated water contributes to diseases in humans.  According to World Heath Organization(WHO), people worldwide are affected by water-related diseases or illnesses due to contaminated water.  Water can be contaminated by many factors such as presence of microbiological pathogens or chemicals in water and products and materials that come into contact with water.  In many developing countries, many people suffer from diseases that are caused by contaminated water.  Even though in developed countries people have access to treated water, sometimes there is outbreak of waterborne diseases.  In order to prevent illnesses by water contamination, it is best to have water filter system at homes to filter the tap water again just before we use it.  Even though water treatment systems are effective in developed countries, pathogens can evolve and may not be destroyed by the water treatment or chemicals can be dissolved in water on its route to the tap.  Using clean water is the key to prevention of many health issues.  Therefore, you can take an extra step to prevent any microbiological pathogens or chemicals that may come through the tap by having a water filter systems at home.