Plumbing Systems in Southeast Michigan Homes: What Inspectors Check Beyond the Sewer Line

When people think about plumbing during a home inspection, they usually think of the sewer scope. But the pipes that bring water into a house deserve just as much attention as the ones that carry waste out. In Southeast Michigan, where housing stock spans everything from 1920s Detroit bungalows to 1990s Macomb County subdivisions, supply plumbing varies widely — and so do the problems.

Here's what inspectors are actually looking for when they check a home's plumbing system.

Pipe Material Tells a Story

The material running through a home's walls often reveals its age and risk level faster than anything else.

• Galvanized steel: Common in homes built before the 1960s, especially throughout Detroit, Dearborn, and older Oakland County suburbs. These pipes corrode from the inside out, gradually restricting flow. Reduced water pressure at upper-floor fixtures is often the first clue.
• Polybutylene: A gray plastic pipe used in some homes built between the late 1970s and mid-1990s. It has a history of unpredictable failure and is flagged whenever it's found.
• Copper: The long-standing standard, generally durable, though inspectors still check for pinhole leaks, corrosion at joints, and signs of old repairs.
• PEX: Common in newer construction and re-pipes. Generally reliable, but inspectors check fittings and connections for proper installation.

Water Pressure and Flow

Inspectors run multiple fixtures at once to see how the system handles demand. A toilet that struggles to refill while the shower is running, or a kitchen faucet that trickles when the washing machine is going, points to undersized or restricted piping — a common issue in older homes that were never designed for modern water use.

Shutoff Valves and Accessibility

A surprising number of Southeast Michigan homes have main shutoff valves that are corroded, painted over, or nearly impossible to reach. Inspectors test whether the main shutoff actually functions, since a valve that won't close is a real problem in an emergency. Individual fixture shutoffs under sinks and toilets get the same check.

Water Heater Connections

While the water heater itself gets its own evaluation, inspectors also look at the supply and shutoff connections feeding it, checking for corrosion, improper fittings, or signs of past leaks around the base.

Visible Leaks and Water Staining

Under sinks, around toilet bases, in basement ceilings below bathrooms, and near exposed pipe runs — these are the spots where slow leaks show up first. Even a small amount of staining or mineral buildup is worth noting before it becomes a bigger repair.

Cross-Connections and Backflow Risks

Older homes sometimes have plumbing modifications made without proper backflow protection, particularly around utility sinks, irrigation hookups, or older boiler systems. Inspectors check for these connections since they can allow contaminated water back into the supply.

Why This Matters for Buyers and Sellers

Plumbing issues rarely show up as one dramatic failure. They show up as slowly declining pressure, a small stain that keeps reappearing, or a valve that doesn't turn. Catching these signs early gives buyers a clearer picture of upcoming maintenance and gives sellers a chance to address small issues before they affect a sale.

A thorough inspection looks at the whole water system, not just what happens when you flush. In a region with as much housing-age diversity as Metro Detroit, that full picture matters.

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