Definition
Supply lines are the pipes bringing fresh water from your water source to your faucets. Corroded or failing supply lines cause low pressure, discolored water, or leaks—and they're expensive to replace.
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Water supply lines deliver hot and cold water under pressure to all fixtures. Copper is traditional and durable but expensive; PEX (cross-linked polyethylene) is flexible, affordable, and increasingly popular; CPVC handles hot water better than PVC. Older homes may have galvanized steel (prone to corrosion and mineral buildup). Problems include leaks, corrosion, mineral deposits, and inadequate pressure. Inspectors assess visible supply line materials, look for leaks, and test water pressure and quality.
Pro Tip
If you notice discolored water or low pressure, have supply lines evaluated. Replacement may be more cost-effective than treating the symptoms.
Example
An inspection of a 1960s home revealed severely corroded galvanized supply lines causing low water pressure and rust-colored water. Replacement with modern PEX tubing cost $3,200 but restored adequate pressure and clean water.