Decide if a filter subscription truly pays off by mapping your water profile, verifying NSF/ANSI certifications, and calculating real per-gallon cost from certified capacity. Avoid common traps and use flexible, usage-based delivery only when it clearly saves money and waste.

Pick an under-sink RO you’ll actually maintain by prioritizing clearance, tool-free service, real flow at low pressure, and verified low-waste ratios. Use the 5-minute cabinet precheck and compare three vetted models sized for tight kitchens, well water, and tight budgets.

Troubleshoot water filters with data, not guesswork by mapping contaminants and choosing certified solutions. Use simple checks and calculations to fix low pressure, prevent leaks, set accurate replacement intervals, and verify results and cost per gallon.

Make an informed choice with side-by-side, lab-verified field tests covering flow, lifespan, certifications, and cost per gallon - plus scenario-based picks (ultralight, group, viral risk), maintenance tips, and multi-barrier strategies for emergencies and wells.

Test first, then match AIO, chemical injection, or catalytic media to your water chemistry. Verify certified reduction at your actual flow rate and compare 5-year costs to get reliable treatment without overspending.