Obviously it varies. But having plumbed entire houses, I can tell you that it adds up. Supply line in the basement, a run to the water heater(s), then forking

Obviously it varies. But having plumbed entire houses, I can tell you that it adds up. Supply line in the basement, a run to the water heater(s), then forking into two parallel lines (hot and cold) to supply kitchen(s) and bathroom(s), verticals to get to higher floors, sometimes horizontal runs if the bathrooms are not stacked, etc. Cold supply to the outdoor spigots. Even small single-story houses with perfectly located utilities will have several dozen feet of potable water lines. Add stories or less-convenient utility locations and you can be well into the hundreds.