Galvanized Pipe
Galvanized pipe is old steel water pipe coated in zinc that corrodes and clogs from the inside over decades, a common cause of low pressure and rusty water in pre-1970 homes.
Galvanized pipe is steel dipped in zinc to fight rust, the standard for home water supply for much of the 20th century. The zinc coating eventually wears away, and from there the steel rusts from the inside out. Over forty or fifty years, that internal rust builds up like plaque in an artery, narrowing the bore until a half-inch pipe carries the flow of a pencil. Homeowners notice it as weak pressure that gets worse over the years, especially at the fixtures farthest from the meter.
The other tell is water that runs brown or yellow after the house has sat unused, as loosened rust flushes out of the lines. Because the corrosion is inside the wall of the pipe, you cannot see it from outside; a plumber confirms it by cutting a section or scoping the system. Galvanized pipe also corrodes fastest where it meets copper, so older homes that were partly upgraded often have a trouble spot right at that junction.
There is no real fix for clogged galvanized supply lines short of replacing them. Cleaning or descaling rarely lasts, so the standard recommendation is to repipe the affected runs, or the whole house, in PEX or copper. Galvanized is still used outdoors for some gas and structural jobs, but for interior water supply it is considered obsolete.
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- CPVC : CPVC is a rigid cream-colored plastic pipe rated for hot water that joins with solvent cement, used for water supply as a lower-cost alternative to copper.
- Push-Fit Fitting (SharkBite) : A push-fit fitting is a no-tools connector that seals a pipe joint when you simply push the pipe in, working across copper, PEX, and CPVC, with SharkBite the most familiar brand name.
- Nominal Pipe Size : Nominal pipe size is the rounded label name for a pipe diameter, such as half-inch or three-quarter-inch, which rarely matches the pipe’s actual measured dimensions.
- Slip-Joint Connection : A slip-joint connection seals a drain pipe with a beveled nylon washer compressed by a hand-tightened nut, the take-apart joint used on sink traps and tailpieces.