We often take water coming from the taps for granted, we assume that it is definitely always safe to drink. But it is not always the case, there are many contaminants that can get into our drinking water. Micro-organisms such as bacteria, parasites and viruses might contaminate water. One example is Cryptosporidium, which lives in the intestines of humans and animals, thus it is also found in animal waste. A failure in the water filtration system when recycling sewer water can cause this parasite to slip through and contaminate the drinking water. There was a case in the city of Milwaukee in the United States in 1993, where the city's drinking water was contaminated by cryptosporidium causing the outbreak of cryptosporidiosis affecting almost half a million people.
Aside of parasites, there are other possible contaminants such as lead, arsenic, aluminium, disinfection by products and turbidity. Aluminium is used in water treatment plants , though aluminium is not acutely toxic for humans, there have been studies that suspect that aluminium exposure through higher levels of aluminium in the water may be linked to dementia and acceleration of the onset of Alzheimer's disease. Lead is a toxic metal; water on the way from the treatment plant to your tap can become contaminated by lead from the underground pipes, holding tanks, lead pipes inside old houses, etc. A build up of lead in the body over a long period of time can damage the brain, red blood cells and kidneys. Arsenic occurs naturally in the environment, but with the addition of arsenic coming from by-products of industrial and agricultural activities, there is an increase of arsenic level in the water in some areas. Long term exposure to arsenic has been linked to several types of cancers such as lung, skin, bladder, liver, kidneys and prostate.
Sometimes we can see haziness in the tap water, it is called turbidity. It means the water may contain particles such as silt, decaying plants, parasites and other small particles that are suspended in the water. A high turbidity in drinking water can lead to gastrointestinal diseases.
When you go to a swimming pool, you notice how there is more chlorine the water compared to the drinking water. Chlorine is added to the water as disinfectant to kill harmful micro-organisms. Our drinking water is also treated with chlorine to prevent the spread of water-borne diseases. But there is also a downside as chlorine reacts with natural organic compounds in the water resulting in disinfection by-products or DBP. DBP has been related to the increased risk of developing bladder cancer.
The use of whole house water filter can help remove the above mentioned contaminants. It is important to always check what a filter can remove when selecting a water filter for your house. Which water contaminants a filter is certified to remove under which standards must be listed in the product information. You want to pay attention on the phrasing of the certification. If it says that the product is tested against NSF International protocol, it is not as good as being tested and certified by NSF international. There are also different standards that NSF uses to test the filters. So before you buy your whole house water filter systems, pick a standard you think covers the most prevalent water contaminants in your area. The standards are Standard 42 (aesthetic effects), 53 (health effects) , 55 (ultraviolet treatment), 58 (reverse osmosis) and 62 (distillation). For details of each standard please check NSF site.