What kind of pipes do I have?

Most homeowners never think about their pipes until one leaks. But the pipe material tells you a lot: some materials last for decades, and a few are known to fail. You can usually tell what you have in a few minutes with a flashlight, a coin and a refrigerator magnet.

This guide covers the two kinds of pipe in a house. Supply pipes carry clean water under pressure to your faucets, toilets and appliances. Drain pipes carry used water out of the house. They are often made of different materials.

If you already know you have a problem material, see what a whole-house repipe costs.

Where to look

Start where the main water line comes into the house. That is often in a basement, crawl space or utility closet, near the water meter or the main shutoff valve. [1] If you don't know where that is, see how to find and use your water shutoff.

Then check a few more spots, because one house can have more than one material:

Under the kitchen and bathroom sinks, where pipes come out of the wall
Behind the toilets
At the water heater, where pipes connect at the top
Along the ceiling or floor framing in an unfinished basement or crawl space

Polybutylene, for example, has been found joined to copper in homes that look like they have copper plumbing. Check the whole run where you can, not just one spot. [3]

The coin and magnet test

Your city's water utility may already have a guide for this. The City of Raleigh asks customers to scratch the pipe gently with a coin, then hold a magnet against it. [1]

What you see	Magnet	Likely material
Scratch shows a bright orange, penny color	Doesn't stick	Copper
Hard to scratch, stays dull gray	Sticks firmly	Galvanized steel
Scratches easily, shows shiny silver	Doesn't stick	Lead
White, blue, black or other plastic, no metal shine	Doesn't stick	Plastic (PEX, CPVC, PVC or polybutylene)

The test results above come from Raleigh's service line guide. [1] Raleigh reports it has not found lead pipes in its service area to date. If you think you have lead pipe anywhere, contact your water utility. It can explain testing and next steps.

Copper

Copper is a rigid metal pipe. New copper is shiny and orange. Older copper is usually dull brown, and a light scratch brings back the penny color. [1] Joints are usually soldered, so you'll see a smooth, silver-colored band where pipe meets fitting.

Copper tube often has a colored stripe or printing that shows its wall thickness: green for Type K, blue for Type L and red for Type M. Yellow marks DWV copper, used for drains and vents. [2]

Plan to replace? Usually not. Copper is a long-standing supply pipe. Leaks happen, but they are normally repaired one at a time. See pipe and drain repairs.

PEX

PEX (cross-linked polyethylene) is flexible plastic tubing. It bends around corners, so you'll see long curved runs with fewer fittings. It's sold in red, blue, white and a natural, slightly yellow color. The color doesn't change how the pipe performs. [8] Fittings are usually brass or plastic, held with metal crimp rings or expanded sleeves.

Like most plastic pipe, PEX usually has its type printed along the side. If you aren't sure, read that printing. [6]

Plan to replace? No. PEX is what most repipes use today. See repiping a house.

CPVC

CPVC (chlorinated polyvinyl chloride) is a rigid plastic pipe that carries both hot and cold water. [7] It is usually an off-white or yellowish cream color. [6] Joints are glued, so look for straight runs joined by elbow and tee fittings, with no threads or crimp rings.

CPVC looks a lot like PVC, the white plastic pipe used mostly for drains. PVC isn't rated for hot water, so it shouldn't be on the hot side of a supply system. The printing on the pipe tells you which one you have. [6]

Plan to replace? Not right away. HomeCloud reports flag CPVC pipes so you can keep an eye on them.

Polybutylene

Polybutylene is a flexible plastic supply pipe installed in many homes from 1978 to the mid-1990s. It's most often gray, but it can also be white, silver, black or blue. Blue is usually an outdoor line coming from the meter. Look for the code "PB2110" printed on the pipe. It's usually 1/2 inch to 1 inch around. [3]

Polybutylene was never used for drain lines. [3] Research found that disinfectants in public water can attack the pipe from the inside, so it can fail at any point along the line, not just at the joints, and it can leak without warning. [3]

Color alone isn't proof. Black pipe can be polyethylene, and white pipe can be PVC or PEX. If you aren't sure, a licensed plumber can confirm it. [3]

Plan to replace? Yes. See polybutylene piping and what a repipe costs.

Galvanized steel

Galvanized pipe is steel or iron coated with zinc. It's dull gray, hard to scratch, and a magnet sticks to it firmly. [1] [4] It is joined with threaded fittings, so look for screw-type connections at every turn.

The zinc wears away first, then the steel underneath starts to rust. Rust builds up inside the pipe and narrows it, which can cause low water pressure and discolored water. [4] Galvanized pipe was common before the 1960s and isn't generally used for drinking water today. [4] It eventually corrodes and leaks. [5]

Plan to replace? Yes, plan and budget for it. See galvanized supply piping and repiping a house.

Cast iron

Cast iron is a drain pipe, not a supply pipe. It's heavy, dark gray or black, and much wider than supply lines. A magnet sticks to it. Before 1960, cast iron was the main choice for drain lines, and it rusts over time. [5]

Newer drains are usually plastic: black ABS or white PVC. [5] [6] Many older homes have a mix, with cast iron in the main stack and plastic where drains were repaired.

Plan to replace? Not automatically. A sewer camera check can show the condition of older drains without digging anything up. See cast iron drain pipes and septic and sewer.

Quick summary

Material	Used for	What to do
Copper	Supply	Repair leaks as they come up
PEX	Supply	No action
CPVC	Supply	Keep an eye on it
Polybutylene	Supply	Plan to replace
Galvanized steel	Supply (older homes)	Plan to replace
Cast iron	Drains	Consider a camera check
PVC or ABS	Drains	No action unless it leaks

When to call a plumber

Call a licensed plumber if you find polybutylene or galvanized pipe, if you think you've found lead, or if you see active leaks, rust stains or white crust at the joints. Your local building department sets the rules for which materials are allowed and when a permit is needed, and those rules can differ from one city or county to the next.

HomeCloud is a licensed general contractor that evaluates homes, then prices and does the repairs, including repipes.