What happens inside old galvanized pipe
Galvanized steel pipe was coated with zinc to slow rust. Over decades that coating wears away and the steel underneath corrodes, building up rough deposits on the inside wall. The opening the water flows through gets smaller every year, so pressure drops, especially on the hot side and at fixtures farthest from the main.
Many homes built in La Palma's 1960s and 70s building boom used copper, but some used galvanized steel, and others have a mix where earlier repairs replaced only part of the system. Mixed systems can corrode faster where different metals meet without proper fittings.
How to check what pipe you have
Look under a sink
Follow the supply line back from the angle stop to where it comes out of the wall.
Check the main
Look at the pipe where it enters the house near the main shutoff, and at the water heater connections.
Identify the material
Galvanized is dull gray with threaded joints. Copper is brown or greenish with soldered joints. PEX is flexible plastic, often red, blue or white.
Try a magnet
A magnet sticks to galvanized steel but not to copper or plastic.
Signs the supply lines are failing
- Brown or rusty water when a tap first opens, especially after being away.
- Pressure that has slowly gotten worse over the years.
- Leaks at threaded joints or pinholes along the pipe.
- Hot water pressure noticeably weaker than cold.
- Repeated repairs to different sections of the same system.
Common repipe materials
| Material | Strengths | Things to know |
|---|---|---|
| PEX | Flexible, fewer fittings, routes easily through walls and attics | Must be protected from sunlight and installed with the right fittings |
| Copper (Type L or M) | Long track record, rigid, heat tolerant | More joints, more labor; water chemistry can affect it |
| CPVC | Rigid plastic, used in some repipes | Can become brittle over time; check manufacturer guidance |
How a typical repipe unfolds
Repipes in single-story slab homes usually route new lines through the attic and down the walls instead of through the slab.
- Planning
- The plumber maps every fixture, decides the route and explains what drywall will be opened.
- Permit
- Repiping generally needs a permit. Check with the City of La Palma.
- Install
- New lines are run while the old ones stay live, keeping the time without water short.
- Switchover
- Fixtures are connected to the new lines, and the old pipe is abandoned or removed.
- Testing and inspection
- The system is pressure tested and inspected before walls are closed.
- Patching
- Drywall openings are patched; confirm in advance whether painting is included.
Questions to ask about a repipe
- Which material do you recommend for this house, and why?
- Where will the new lines run, and how many wall openings should I expect?
- Will the main line from the meter be replaced too?
- Is drywall patching and paint included?
- How long will the water be off?
Common questions
Can I replace just part of the galvanized pipe?
Yes, partial replacement is common for a single failing section. If the whole system is galvanized and aging, a plumber may point out that other sections are likely to fail soon too.
Will repiping fix low water pressure?
If the low pressure comes from narrowed galvanized pipe, usually yes. A plumber should rule out a failing pressure regulator or valve first.
Does a repipe affect the slab?
In most single-story repipes the new lines go overhead through the attic, so the slab is not opened.
General information for La Palma, not a quote or professional advice. In an emergency, call 911.