Most online water filtration content is affiliate marketing (including ours, transparently). For unbiased technical information, these are the primary-source authorities:
The EPA publishes the National Primary Drinking Water Regulations and maintains the contaminant database (epa.gov/ground-water-and-drinking-water). Your state's environmental health department typically offers reduced-cost private well testing. NSF International (nsf.org) is the primary third-party certification body for filtration equipment; their listing search lets you verify any product's actual certifications. The WQA (Water Quality Association) provides additional certification and consumer information.
EWG's Tap Water Database (ewg.org/tapwater) lets you look up your zip code and see what contaminants exceed health-based guidelines (which are often stricter than EPA legal limits). Tap Score by SimpleLab is an at-home water testing service that mails samples to a certified lab and provides comprehensive reports.
For PFAS (forever chemicals): the EPA's Final PFAS National Drinking Water Regulation, set in 2024, regulates PFOA, PFOS, and several other compounds at levels much stricter than previous guidance. Check EWG's PFAS contamination map for your area. For lead: EPA's Lead and Copper Rule guidance. For arsenic: USGS arsenic maps for groundwater concentrations by region. For radon in water: state-specific guidance varies; New England states have higher prevalence.
For our reviews, we cross-reference manufacturer claims against NSF certification listings (the gold standard for verifying performance claims), EPA health advisories, and independent testing data where available. We're skeptical of products that market specific contaminant reduction percentages without third-party certification to back them up. When the science is contested or in flux (as with some emerging contaminants), we say so rather than picking a side.
Understand what's in your water and how different filtration methods work.
What's actually in your water? A guide to chlorine, lead, PFAS, bacteria, and other common concerns.
Different water sources have different filtration needs. Learn what to consider for each.
What hard water is, how it affects your home, and whether you need a water softener.
Understanding TDS readings, what they mean, and whether high TDS is actually a problem.
Decode your annual water quality report (CCR) and understand what the numbers mean.
How RO works, what it removes, pros and cons, and whether you need it.
The science behind carbon filtration, mechanical filtration, and chemical removal.
Which filtration technology is right for your needs? A detailed comparison.
Pros and cons of each for basic kitchen filtration.
Should you filter all your water or just what you drink?
They're not the same thing. Learn the difference and which you need.
Cost, quality, and environmental comparison.
Understanding filter certifications, when filtered water is safer, and potential concerns.
Sources of lead contamination, health effects, and which filters remove it.
Why it's there, potential concerns, and easy ways to remove it.
The debate, health considerations, and filters that remove fluoride.