Search faucet lifespan and most sites say "15 years." So you buy one. It leaks at year six. You figure it's a lemon. It's not. You just asked the wrong question.
A faucet isn't one thing. It's a handful of parts, each on its own clock. Whichever one quits first decides the lifespan. Not the average. Not the warranty. The weak link.
Every handle hides a ceramic disc cartridge — the valve that opens and closes the water. EN 817 tests these to 500,000 cycles. In a kitchen with 40 uses a day, do the math. That's north of 30 years. Every batch in our factory runs through this. QC tears them down. The discs rarely gave out. Clean. Tight. Smooth as day one.
O-rings and seals. Hard water chews at them. Chlorine doesn't help. The rubber stiffens, the seal face warps, and there's a drip where none should be. Five to eight years. That is the actual clock.
The aerator gums up sooner — two, three years in hard-water country. Flow fades. People blame the faucet.
Finish is its own thing. Chrome and PVD last. Brushed nickel shows grip-point wear around year seven. Mechanism fine. Exterior reads old.
A faucet with a great cartridge and cheap seals isn't a good faucet. It looks good until the rubber fails. The "15-year" number means nothing if the first failure was a fifty-cent decision. Don't shop the number. Shop the weakest link.