What certification does not cover

The standards include structural requirements for a housing that holds pressure, which is a real thing and not nothing. What they do not do is predict how a specific cartridge holds up in a specific fridge over years of thermal cycling, or whether the seal on the model you bought is the same seal it had two production runs ago.

A certificate is a snapshot of a tested configuration. Reviews complaining about leaks are not evidence that a certification was wrong; they are evidence about a question the certification did not ask.

This is the one that costs people money. A cartridge certified to all three standards will still not go into a refrigerator it was not made for, and a certification mark has nothing to say about the cartridge code, the bayonet, or the chip your fridge is looking for.

Fit statements on aftermarket listings come from the seller. Fit statements on genuine listings come from the manufacturer. Neither is a certification, and the model pages on this site keep those two apart on purpose.

Rated capacity is tested capacity under a test protocol. Your household has its own throughput, its own incoming water and its own habits. A cartridge rated for 200 gallons in a laboratory does not become a six month cartridge in your kitchen by declaration.

Where a manufacturer states both a months figure and a gallons figure, the practical rule is to replace at whichever arrives first. The filter life tool on this site does that arithmetic with a number you supply and prints the formula it used.

A certification for cyst reduction is silent on lead. A certification under 42 is silent on everything in 53. A product with no certification named is silent on all of it. Silence is the correct reading in each case, and this site prints an empty cell rather than a guess.

And none of the four standards pages is about safety in the ordinary sense of the word. Household drinking water filters are designed for water that is already fit to drink. They are not intended for microbiologically unsafe water and they do not replace a boil water advisory. If you suspect contamination, contact your utility and your local health department, read your Consumer Confidence Report, and use the EPA resources below.