How we research

Our guides are research-based. Unless a page says otherwise, we have not installed the products in our own homes, and we won't pretend we have.

What we look at

• Specifications from the manufacturer: grain capacity, flow rate (GPM), media, stages, warranty, price.
• Independent certification: whether a claim is backed by an NSF/ANSI or WQA certification, and for which standard. A product "tested to" a standard is not the same as "certified to" it.
• Public data: EPA drinking-water standards, USGS hardness data, CDC and EPA guidance for private wells.
• Fit for the problem: no single system fixes everything; we match equipment to the water test result.

Keeping it fair

Some links earn us a commission. That never decides what we recommend, and we include models from brands that pay us nothing when they're the better fit. Prices change often, so we show the seller's listed price and link to the seller for today's price. We don't show a maker's "compare at" price as a discount.

Corrections

Spotted an error or an outdated spec? We fix mistakes as soon as we can verify them, and update the date at the top of the page. Tell us here.