Types

• 1). Determine which type of house water filtration system is right for you. Two of the most common ones are filtration and reverse osmosis. Reverse osmosis filters water by pushing it through a semi-permeable membrane. The main filter medium for filtration systems is carbon. It blocks or attracts contaminants as they pass through a carbon filter. This system can filter out particles greater than 0.5 or 10 microns. Reverse osmosis systems can filter more effectively, but are considered less efficient and more expensive.
  
  
• 2). Compare the cost of different house water filtration systems based on their initial and long-term cost. Initial cost simply means how much you will pay today to own the system. The long-term cost refers to the average yearly or daily cost you will pay to replace cartridges and maintain the system. Reverse osmosis systems require electricity, while filtration ones do not.
  
  
• 3). To rule out systems based on performance, request documentation from companies and get reviews and comparison charts. If any systems fail to filter out at least 99 percent of chlorine, take them off your list, because a whole house filter should pass this test if it has quality stages and filter media. Now, do a side-by-side comparison of individual chemicals, and see which brands come out on top.
  
  
• 4). Narrow the choices by checking to see which ones were certified by at least one of the two strictest rating organizations, the National Sanitation Foundation (NSF) and Underwriters Laboratories (UL). After eliminating brands without certification, compare how many gallons each unit can filter. Lastly, look at what chemical was tested and for how long, and each unit's effectiveness at filtering it.
  
  
• 5). Review type, costs, performance and certification. Eliminate the house water filtration systems that failed or had the lowest ratings for the above steps. Then find the best performers. Each of the above steps will lead to the elimination of some models. The process-of-elimination method will lead you to the best choices, which are not necessarily the most expensive systems.