Methodology
How we judge filters, brands, and product claims.
The goal is not to crown a universal winner. The goal is to match a specific water problem to the right technology, certification, and ownership model.
What goes into a guide
We use manufacturer documentation, public specifications, EPA guidance, NSF/WQA/IAPMO lookup resources where applicable, performance data sheets, and plain ownership math: replacement cost, flow, installation, space, wastewater, and support.
How we use certification claims
A claim is only useful when it is tied to the exact model. We separate NSF/ANSI standards, third-party certification listings, manufacturer-tested performance data, and broad marketing copy.
How we use manufacturer replies
Manufacturer responses can clarify model numbers, warranty terms, replacement-filter cadence, certification scope, or support coverage. They do not improve placement on their own.
How verdicts are formed
We judge fit, not prestige. A pitcher can be a better recommendation than a premium RO system for a renter with lead concerns and no install rights. A tank RO can be better than a sleek tankless system when ownership cost matters more than cabinet space.
Health and safety framing
Water quality can be health-relevant. We do not diagnose water. For private wells, microbial concerns, boil-water alerts, or regulated contaminants above limits, we point readers toward lab testing, local health guidance, and certified treatment professionals.