What an inspection covers, and what it honestly cannot
An inspection is a visual and functional survey of everything reachable: the water service and its material, the meter and main shut-off, visible supply piping, the water heater and its venting, fixtures under real load, exposed drainage and venting, and the accessible part of the building drain.
What it cannot do is see through finished walls, floors and ceilings. Nobody can tell you the condition of a drain buried in a slab or a supply line inside a closed wall from the outside, and a report that claims otherwise is guessing. What we can do is read the evidence: pipe material where it is visible, pressure and flow under load, staining, corrosion at joints, and how the drains behave under a real volume of water. Then we tell you what that evidence supports, and where it runs out.
When something matters enough to know for certain, we say what it would take to find out: a camera down the lateral, a small opening in drywall, an isolated pressure test on one section. Those are separate decisions with their own cost and mess. We would rather you make them knowingly than have us write a confident sentence about a pipe neither of us has seen.