The first step is to determine what you want the filter or treatment device to do. Do you want it mainly to remove tastes and odors? To remove contaminants, such as lead? Before you buy a filter, you may want to find out if the contaminant is a problem in your home.
Not all filters are the same. Read the packaging carefully and only purchase a filter certified by NSF/ANSI (National Science Foundation/American National Standards Institute). Here are some standards to look for:
- NSF/ANSI Standard 42: Filters with this certification change the aesthetics of the water and reduce non-health-related contaminants. The contaminants reduced will vary by filter.
- NSF/ANSI Standard 53: Filters with this certification reduce contaminants that are harmful to health. The contaminants reduced will vary by filter.
- NSF/ANSI Standard 58: This certification applies to reverse osmosis treatment systems.
- NSF/ANSI Standard 177: This certification applies to showerhead filtration systems, for the reduction of free chlorine.
Don't rely on the NSF/ANSI certification alone; make sure the packaging specifically lists the contaminant you wish to reduce. For example, you may find two filters that are both NSF/ANSI 53-certified, but only one of them may be certified for lead reduction.