Supply pipes carry pressurized water — both hot and cold — to every fixture in the house. The material determines lifespan, repair approach, and failure mode. Most homes have one dominant material with transitional sections in different materials where repairs or additions were made over the years.
| Material | Appearance | Common era | Lifespan | Status |
|---|---|---|---|---|
| Copper | Orange-brown, rigid | 1950s–present | 50–70 years | ✅ Still the standard |
| CPVC | Cream/yellow, rigid | 1970s–present | 50–75 years | ✅ Reliable for hot and cold |
| PEX | Flexible, red/blue/white | 1990s–present | 40–50 years | ✅ Dominant in new construction |
| Galvanized steel | Grey, rigid, magnetic | Pre-1960s | 20–70 years | ⚠️ Corrodes internally — monitor |
| Polybutylene | Grey or blue, flexible | 1978–1995 | Unpredictable | ❌ Re-pipe recommended |
Copper has been the professional benchmark for residential supply plumbing since the 1950s. It's durable, biologically inert, and tolerates both hot and cold water across the full pressure range used in residential systems. A well-maintained copper system can last 70 years or more.
The main vulnerability is water chemistry. In areas where municipal water is acidic — a pH below 7 — copper corrodes from the inside, eventually developing pinhole leaks that are difficult to locate and expensive to repair. Blue-green staining around fixtures or joints is oxidized copper and the clearest visible sign of active corrosion. Well water with high acidity is a common cause in rural properties. If you have copper pipes and see this staining, a water chemistry test is the right first step before any repair work.
Copper is also the most expensive supply pipe to install today, which is why PEX has displaced it in most new residential construction — though copper remains the preferred material for gas lines and high-temperature applications where PEX is not rated.
Cross-linked polyethylene — PEX — became the dominant residential supply pipe material in the US during the 2000s and remains so today. It's flexible enough to be routed through walls and floors without fittings at every bend, freeze-resistant in ways that copper and rigid plastics are not, and significantly faster to install than copper, which reduces labor costs.
PEX is color-coded: red for hot supply lines, blue for cold, and white for either. The three variants — PEX-A, PEX-B, and PEX-C — differ in manufacturing method and flexibility, with PEX-A being the most flexible and most commonly used in residential plumbing.
The practical limitations of PEX are few: it cannot be used outdoors or in UV-exposed locations without UV-resistant sheathing, and it requires specific push-fit or crimp fittings rather than the soldered connections used with copper. PEX is not compatible with standard copper compression fittings — the correct transition fitting must be used wherever the two materials meet.
Galvanized steel pipe was standard in residential construction through the 1950s and remained in use into the 1960s. It's a steel pipe coated with zinc to delay corrosion — but that coating degrades over time, and once it's gone the steel itself corrodes from the inside out. The result is gradual internal narrowing that reduces water flow, discolored water, and eventually pinhole leaks or joint failures.
If your home has galvanized supply lines and was built before 1960, the pipes have exceeded or are approaching the end of their useful life. The symptom most homeowners notice first is low water pressure at fixtures farthest from the main — the corrosion builds up preferentially at horizontal runs and elbow fittings, creating flow restrictions that worsen over years. Replacing a galvanized supply system is a significant project but is typically more cost-effective than repairing individual failures as they occur.
Polybutylene (PB) pipe was installed in an estimated 6 to 10 million US homes between 1978 and 1995. It was inexpensive, flexible, and easy to work with — and it became the subject of a major class action settlement after widespread failures linked to chlorine degradation. The chlorine in municipal water reacts with the pipe material over time, causing surface cracking and eventual failure at fittings and along the pipe body.
Polybutylene is identifiable by its grey or blue color and flexible form — it resembles PEX but predates it. Fittings are typically grey plastic or aluminum compression fittings. If your home was built between 1978 and 1995 and you haven't confirmed the supply pipe material, checking an exposed section under a sink or in a utility room is worth the two minutes it takes.
There is no repair approach that addresses the underlying degradation. If polybutylene is present throughout the supply system, a full re-pipe is the recommended course of action. A licensed plumber can assess the extent of the material in your home and provide a replacement cost estimate. In areas where PB failures have been common, some homeowners insurance policies now exclude coverage for PB-related water damage.
Drain-waste-vent (DWV) pipes carry wastewater out by gravity and don't operate under pressure, which simplifies the material requirements considerably. Most homes fall into one of two categories based on age.
White PVC is the standard drain pipe material in homes built since the early 1970s. It's lightweight, easy to cut and join with solvent cement, and essentially indefinite in lifespan under normal drain conditions. PVC drain pipe rarely fails spontaneously — most issues involve joint failures from improper installation or physical damage.
Older homes typically have cast iron drain stacks — the large vertical pipes that run from the fixtures to the sewer line. Cast iron is heavy and durable, with a natural lifespan of 80 to 100 years, but failures occur at joints where the lead or rubber caulking has deteriorated, and at horizontal runs where the pipe sits in soil or concrete. A camera inspection of a cast iron drain system in a home over 50 years old is useful context before any significant plumbing work.