How We Research

Quick answer

Filtiva guides are built from government health agencies, standards bodies, university extension research, published cost data, and manufacturer documentation. We verify certifications in public databases, cite every key fact, and clearly state that we have not hands-on tested products unless a page says otherwise.

Our sources (in order of trust)

  1. Government and public health agencies: U.S. EPA, CDC, USGS, and state health departments
  2. Standards and certification bodies: NSF (NSF/ANSI standards and listings) and the Water Quality Association (WQA Gold Seal)
  3. University extension research: peer-reviewed extension publications, such as those from the University of Nebraska–Lincoln
  4. Manufacturer documentation: owner's manuals, spec sheets, and installation guides, used for product-specific facts and always attributed to the maker
  5. National cost data publishers: such as Angi and HomeGuide, shown side by side when they disagree and labeled as estimates
  6. Community discussions: used only to understand common questions and problems, never as a source of facts

How we evaluate products

We do not claim hands-on testing. Instead, we compare products on criteria you can verify:

  • Certification: Is the model certified (not just "tested to") a relevant standard, such as NSF/ANSI 42, 44, 53, 55, 58, or 401? We check the NSF or WQA database.
  • Fit for the problem: Does it address the contaminant or issue a water test shows?
  • Efficiency: For softeners, demand-initiated regeneration and the NSF/ANSI 44 Efficiency Rating.
  • Capacity and flow: Is it sized for real households?
  • Operating cost: Price and life of replacement filters, salt, lamps, or membranes.
  • Warranty and support: Length and coverage, as published by the manufacturer.
  • Manufacturer limits: Water conditions the maker says the product needs.

If we ever do hands-on testing, we'll describe our exact method on the page.

Our sources policy

  • Every statistic, cost figure, health claim, and product spec links to its source.
  • We prefer primary sources and link directly to them.
  • We note the date we checked product facts and certifications.
  • Cost figures are labeled as national estimates, not quotes.
  • We never invent test results, prices, or specifications.

Health and safety content

Water quality can affect health. Our guides are educational and don't replace advice from your doctor, local health department, or a licensed plumber or water treatment professional. For private wells, we follow CDC and EPA testing guidance.

Updates and corrections

We review key guides at least every 6 months and whenever standards, prices, or products change. Each page shows its last updated date. If you find an error, please contact us. We fix confirmed errors promptly and note significant corrections on the page.

Independence

Affiliate relationships never change our criteria. Brands can't pay to be included or to change a ranking. Read our affiliate disclosure.