Galvanized or Polybutylene Water Line: When to Replace It
Many older homes still have a main water line made of galvanized steel or polybutylene. Both have known weak spots. Here is how to tell what you have and what your options are.
Referral service: Gardena Water Line Pros is not a plumbing contractor. Your call may be connected to an independent, third-party service provider who sets its own availability, pricing and terms. Read our referral disclosure.
The short answer
If your main water line is galvanized steel or polybutylene and you have low pressure, rusty water or more than one leak, replacing the line is usually worth discussing with a provider. Both materials are common in older homes, and both tend to fail from the inside, so one repair does not always fix the problem.
How to tell what your water line is made of
Check the pipe where it comes out of the ground near the house, or at your main shutoff valve:
| Material | What it looks like | Quick check |
|---|---|---|
| Galvanized steel | Dull gray metal, threaded joints | A magnet sticks to it |
| Polybutylene (PB) | Flexible plastic, often gray, blue or black | May be stamped "PB2110" |
| Copper | Orange-brown metal, may turn greenish | Magnet does not stick; scratch shows a copper color |
| PEX or polyethylene | Flexible plastic, often white, red, blue or black | Usually printed with "PEX" or "PE" |
The part you can see may not match the buried section. A provider can confirm the material along the whole line.
Problems with galvanized water lines
Galvanized steel pipe is coated with zinc, but over time the inside can corrode. Rust and mineral buildup narrow the opening that water flows through. Common signs:
- Pressure that has slowly dropped over the years, especially when two fixtures run at once
- Brown or rusty water, often after the water has been off
- Leaks at threaded joints, which are the thinnest part of the pipe
Read more in low water pressure in the whole house.
Problems with polybutylene water lines
Polybutylene was a low-cost plastic pipe used in several million US homes from about 1978 to 1997. Chlorine and similar disinfectants in treated water can deteriorate the pipe and its fittings from the inside, and failures can happen with little warning, according to Wikipedia's overview of polybutylene.
Problems with polybutylene plumbing led to a nationwide class action, Cox v. Shell Oil, with a settlement approved in 1995 that covered property owners with polybutylene plumbing and yard service lines, as described by the law firm Lieff Cabraser. The claim deadline for that settlement has passed.
Repair or replace an old water line?
- One leak, otherwise sound line: a section repair may be reasonable.
- Repeated leaks, low pressure or rusty water: replacing the line from the meter to the house is often discussed.
- Selling or buying a home: inspectors and insurers may ask about galvanized or polybutylene plumbing.
See water line repair vs. replacement, main water line replacement in Gardena and trenchless options.
What new water lines are made of
Replacement service lines are commonly copper, PEX or polyethylene. The right choice depends on local code, soil, the connection at the meter and the provider's recommendation. Ask why they recommend a particular material.
This guide is general information, not a diagnosis. An on-site assessment by a qualified provider is the only way to know what's happening with a specific line. Gardena Water Line Pros is a referral service, not a plumbing contractor.
Read next
Frequently asked questions
How do I know if my water line is galvanized or polybutylene?
Look where the line enters the house or at the main shutoff valve. Galvanized steel is a dull gray metal pipe with threaded joints; a magnet sticks to it. Polybutylene is a flexible plastic pipe, often gray, blue or black, sometimes marked "PB2110". A provider can confirm the material of the buried section.
Should I replace a galvanized main water line?
Galvanized steel can corrode from the inside, narrowing the pipe and causing low pressure, rusty water and leaks. If your line is galvanized and you have those symptoms or repeated leaks, replacement is usually worth discussing with a provider.
Is polybutylene pipe still a problem?
Polybutylene was widely installed in the US from about 1978 to 1997. Chlorine in treated water can degrade it from the inside, and it can fail without warning, according to Wikipedia's overview of polybutylene. Many homeowners and insurers treat it as a material to replace.
Can I just repair one leak on an old galvanized or polybutylene line?
Sometimes, but a spot repair on aging pipe may only fix the weakest point. Ask the provider about the condition of the rest of the line before deciding.
Old galvanized or polybutylene water line?
Call to be connected with an independent water line provider serving Gardena, when one is available.
Referral service: Gardena Water Line Pros is not a plumbing contractor. Your call may be connected to an independent, third-party service provider who sets its own availability, pricing and terms. Read our referral disclosure.