Be sure that the system you choose is third-party certified by NSF (National Sanitation Foundation) International or the Water Quality Association (WQA). Remember that displaying the WQA logo may only signify that the company is a member of the Water Quality Association, not that its products are validated. Just because a product is NSF certified against some contaminants doesn’t mean it protects you against all of them.
Make sure that the system you choose is specifically certified to reduce the contaminants from which you wish to protect your family. Be wary of systems that carry only the NSF “component” certification, which indicates that only a single component of the system is certified and may not reflect overall system capabilities.
Check the Internet or publications you trust for reviews of water treatment products. They can provide you with additional information that can help you make a decision.