In recent years, some home drinking water has been found to contain many hazards that standard municipal water treatment procedures don't remove. To eradicate some of the chemicals and toxins that can find their way into drinking water, some homeowners install water treatment devices.
Built-in water filters use several different technologies to clean water. Some filters use only one of these methods, while others take advantage of two or more in order to combat a wide range of contaminants.
A reverse-osmosis (RO) filter removes nearly all contaminants, particularly when combined with carbon filtration. Installed beneath the sink and connected directly to plumbing, it forces water through a membrane that permits only pure water molecules to pass.
Most water problems occur with small water utilities or wells, since small suppliers don't administer quality tests frequently. The right filter for your home depends on the contaminants that need to be removed, which must be determined by testing. The only way to be sure about water quality is to have your tap water tested by an independent lab. Depending upon the number of pollutants you want to check for, this can be expensive.
The most affordable testing option is to contact a national mail-order laboratory that specializes in water analysis, such as National Testing Labs (800-458-3330) or Suburban Water Testing (800-433-6595). They will send you instructions and a water sampling kit that you return by mail.