The results of such a test could affect your choice of filter and help you decide whether you actually need one. Keep in mind that a thorough test can easily cost more than a hundred dollars. Chlorine and lead are the two most common contaminants in water.
Chlorine produces by-products that contribute to cancer and birth defects.
The chemical itself may contribute to heart disease. Lead is toxic even in small amounts. High-level lead poisoning can cause organ damage and stunt the nervous system, leading to mental retardation. In many cities, public health officials are finding water contaminated with cryptosporidium, a microbe that can cause great harm to people with compromised immune systems. Before buying a filter, be sure to check out the different kinds available.