All performance claims and pricing were taken from the Manufacturer's or Authorized Distributor's literature and/or published certified performance claims.

Many models were considered and not included in this comparison because of undocumented or seemingly exaggerated performance claims. Only performance claims that have been certified by NSF or UL are considered "Certified" in our comparisons.

WQA is a Trade Group that allows members to claim certification without full compliance to industry standards. We found that WQA did not require sufficient data from manufacturers to ensure accurate performance claims. We recommend that you insist on UL (Underwriters Laboratories) or NSF Certification to ensure quality and safety compliance.