What we learned testing eight kitchen water filters
Six months, one kitchen sink, and a lab bill we would rather not discuss.
We put eight widely sold water filters through six months of ordinary use in one kitchen: three pitcher models, three faucet-mounted units, and two under-sink systems. We sent samples to an independent lab at the start, the midpoint, and the end. The results rearranged our assumptions.
The numbers were closer than the prices
On the contaminants most city dwellers actually care about — chlorine taste, lead, common disinfection by-products — every unit that carried a current NSF/ANSI certification performed within a fairly narrow band while its cartridge was fresh. The $30 pitcher and the $200 under-sink system were not twins, but they were relatives.
The gap opened at month three. Pitcher cartridges pushed past their stated capacity — which most households quietly do — lost effectiveness fastest. The under-sink units barely drifted.
Friction decides everything
The pitcher had to be refilled about nine times a day for a family of four, which is why it ended the test living half-full in the refrigerator of a household that had gone back to tap. The faucet units stayed in use but slowed the flow enough to annoy. The under-sink systems were forgotten entirely — which, for a filter, is the highest compliment there is.
Our practical takeaway: buy whichever certified format you will actually maintain, put the cartridge date on the calendar the day you install it, and check your utility's annual water report before spending anything — some of what filters promise to remove may not be in your water to begin with.