One of the hardest certifications for water filter manufacturers to receive is certification by Underwriters Laboratories. The main reason is cost and time. It is very expensive and can take over a year to receive certification. So when you come across a statement like this “This system has been tested by Underwriters Laboratories according to ANSI/NSF Standard 42 for the reduction of the substances listed below.
The concentration of the indicated substances in water entering the system was reduced to a concentration less than or equal to the permissible limit for water leaving the system as specified in NSF/ANSI Standard 42.” It should give you a sense of assurance of the manufacturers commitment to quality and longevity.

So we felt pretty comfortable purchasing a Aquasana EQ-300-85 for our well water. The cost of this filter is very reasonable also at under a thousand dollars is a great value. The system lasts three years and replacement cost is a few hundred less. Our plumber installed ours in a few hours and we are very excited to have our “whole house” have filtered water.