Once galvanized supply pipe has corroded enough to cause low pressure, discolored water or leaks, most owners replace it with either copper or PEX. Copper has been the standard for generations: rigid tubing joined with soldered or pressed fittings. PEX is cross-linked polyethylene tubing that bends around corners and is joined with crimp or expansion fittings.
In an older house the practical differences matter more than the material itself. Plaster walls, a raised floor with a crawlspace, an attic, and how runs were laid out decades ago all shape how easily new pipe can be routed, and how many openings will be needed.
How they compare in an older building
Copper
- Rigid lengths with fittings at most changes of direction
- Long-established and familiar to inspectors and future plumbers
- Often needs more or larger wall openings to run straight lengths
- Can develop pinhole leaks over time in some water conditions
- Needs care where it meets remaining galvanized pipe to limit corrosion at the joint
PEX
- Flexible tubing that can be snaked through walls and floors with fewer fittings
- Often allows fewer openings in plaster or finished walls
- Must be kept away from sunlight and some heat sources
- Fittings and the installer's tools must match the PEX system used
- Less tolerant of later damage from nails or screws in walls
Building features that affect the choice
| Feature | Why it matters |
|---|---|
| Raised foundation with crawlspace | Main runs can go under the floor, reducing wall openings for either material |
| Slab foundation | Pipe is usually rerouted through walls and attic instead of the slab |
| Plaster and lath walls | Openings are harder to patch invisibly, so fewer access holes is a bigger advantage |
| Two stories | Vertical runs to an upper bathroom drive much of the routing work |
| Mixed old and new pipe | Every connection to remaining galvanized pipe is a potential weak point |
What drives the cost of a repipe
- Number of fixtures and bathrooms being reconnected
- Access: crawlspace, attic, finished basement or none
- Number and size of wall and ceiling openings
- Whether patching and painting are included
- Replacement of shutoff valves and fixture stops at the same time
- Permit and inspection requirements; check with the City of Fullerton
Questions to ask before choosing
- Which material do you recommend for this building, and why?
- How many openings do you expect, and where?
- Will the line from the meter to the house be replaced too?
- How will the new pipe be supported and protected inside walls?
- Who patches the openings, and to what finish?
Common questions
Is one material always better for older homes?
No. Both are used successfully in older buildings. The deciding factors are usually access, wall finishes and the installer's experience with the system.
Can copper and PEX be mixed in the same house?
Yes, plumbers often use transition fittings between them, for example copper near the water heater and PEX for branch lines. Ask how and where transitions will be made.
Does hard water matter for the choice?
Hard water causes scale in any piping and in fixtures and water heaters. Ask the plumber whether local water conditions affect their recommendation.
General information for Downtown Fullerton, not a quote or professional advice. In an emergency, call 911.