Planned in stages, ageing in stages
Valencia was planned rather than grown. Building began in the mid-1960s and carried on for decades, which means the housing stock is not one generation but several — early tract homes and houses barely twenty years old, a few minutes apart.
So there is no single Valencia answer. The oldest sections are at the point where the water heater, the pressure regulator and the supply fittings have all passed their design life within a few years of each other, and replacing one at a time gets expensive. The newest sections almost never fail at the pipe; when something goes there it is a fixture, a regulator or a heater.