How we research

We are not a lab and we are not a plumber. Here is exactly what we do instead, so you can judge our numbers yourself.

What we do

• Specifications and certifications. We read manufacturer spec sheets and verify claims against the public NSF/ANSI certification database (standards 42, 44, 53, 58, 401). If a claim is not certified, we say so.
• Review analysis. For each product we categorize hundreds to thousands of customer reviews from multiple sources into themes (leaks, flow, salt use, support) and report the share of reviews mentioning each. We quote reviews with attribution; we never write fake ones.
• Expert interviews. We interview certified water treatment specialists and plumbers and publish their answers with their names.
• Transparent calculators. Every calculator shows its formula and assumptions on the page. The sizing rules are standard industry rules, not our invention.

What we do not do

• We do not own, install or lab-test the systems we cover. Any page that says "tested" on this site would be a lie, so you will not find that word here.
• We do not rank products by commission. Affiliate relationships are disclosed on every page that has them.
• We do not hide the DIY path. If a Fleck or Clack valve from a local dealer is the better buy for you, we say so, even though the big direct-to-consumer brands pay better commissions.

How we make money

Some links are affiliate links: if you buy through them, the seller pays us a commission and you pay the same price. We may also show ads and, in future, sell our own guides. None of this changes the math in our calculators or the data in our tables.

Corrections

If you find an error in a number or a certification claim, email us and we will fix it and note the correction on the page.