Silent Spring Institute

Information about water treatment

Home water treatment systems can remove certain contaminants from well water.  Before purchasing a home water treatment system, it is important to get your well water tested so that you know which contaminants are of concern.

This table shows which types of home water treatment systems are effective at removing certain contaminants from well water. 

  Ion exchange Activated carbon Activated alumina Reverse osmosis Distillation Chlorination Aeration
Volatile organic compounds (VOCs)          

UV light and mechanical filters are not effective for any of these contaminants.  These types of treatment can be useful for other types of contaminants. Boiling water will not remove any of these contaminants, and can make them more concentrated in your water.

If you decide to treat your water, there are several things you should keep in mind.

  • What chemicals you want to remove: Different treatment systems remove different chemicals, and it may not be necessary to lower levels of all chemicals in you water. Deciding what the goal of the treatment system is will help you select the appropriate system.
  • Whole-house or point-of-use system: A whole-house system treats all household water for drinking, cooking, showers, clothes washing, etc. Point-of-use systems are smaller and treat only the water that comes through the tap where the treatment system is installed. For example, they can be installed on a kitchen tap and used for drinking or cooking. Depending on the chemicals you are concerned about, you may not need to filter all the water in your home. A whole-house system will not eliminate chemicals associated with the plumbing inside your home because the water is filtered at the point of entry before it is distributed throughout your home.
  • Cost: Consider additional costs beyond just the treatment system itself, including installation and maintenance.
  • Effort to maintain: Think through any part replacement that may need to occur, who will do the maintenance, and any possible need to “flush” the system, which could have an impact on septic systems.


Sources and additional information: