> years

In Phoenix, I've never seen a water filter last because our hard water eats them all up faster than in other places in the US. There must be an ideal combination of filtration systems that others use here and elsewhere that I'm not aware of that last for as long as they do, but standard consumer ones that bring TDS down to zero have very little lifespan here.

I can't imagine what difficulties exist in areas with access to clean water, but I can't expect them to all also be easily filtered outside of processes like solar distillation or something else.