A standard home inspection covers a lot of ground in a few hours, and plumbing is only one piece of it. Inspectors run water, flush toilets, and look for obvious leaks, but they rarely pull apart walls, run a camera through the sewer line, or test water pressure under real load. That leaves gaps that can turn into expensive surprises after you've already signed the paperwork.
THE SEWER LINE IS THE BIGGEST BLIND SPOT
Older homes, especially those built before the 1980s, may still have clay, cast iron, or Orangeburg sewer lines. These materials crack, collapse, or get invaded by tree roots over decades, and none of that shows up from a visual inspection. A sewer camera inspection is the only reliable way to see the actual condition of the line running from the house to the street or septic system. Replacing a collapsed sewer line can cost thousands of dollars, so this is worth requesting before closing.
WATER HEATER AGE AND CONDITION
Most water heaters last 8 to 12 years. A general inspector will note the age from the serial number but won't always flag corrosion, sediment buildup, or a failing pressure relief valve. Ask for the manufacture date and factor a replacement into your budget if the unit is already past the 10-year mark.
SIGNS THAT POINT TO BIGGER ISSUES
- Water stains on ceilings below bathrooms, which often mean a slow leak in the flooring or fixture below
- Slow drains in multiple fixtures at once, which usually points to a main line clog rather than a single fixture issue
- Mismatched pipe materials, such as galvanized steel spliced with copper or PEX, which can signal old repairs and future corrosion problems
- Low water pressure throughout the house, which can indicate galvanized pipe buildup or a failing pressure regulator
- Visible corrosion or green staining around fittings, a sign of ongoing pinhole leaks
GALVANIZED PIPE IS A RED FLAG
Homes built before the 1960s often still have galvanized steel supply lines. These pipes corrode from the inside, gradually restricting flow and eventually leaking. Because the corrosion happens internally, it can go unnoticed until pressure drops noticeably or a pipe fails outright. If a home still has galvanized supply lines, budget for a repipe within the next several years.
WHAT TO DO BEFORE CLOSING
Bring in a licensed plumber for a dedicated plumbing inspection separate from the general home inspection. A plumber will run a camera through the sewer line, check water heater condition, test for adequate water pressure, and identify pipe materials throughout the house. This inspection typically costs a few hundred dollars, which is a small price compared to discovering a collapsed sewer line or a failing water heater after you've moved in.
If problems turn up, you still have negotiating room. Sellers will often cover repairs or adjust the price rather than lose a sale over a plumbing issue that's been documented in writing. Waiting until after closing removes that leverage entirely.