Materials
Pipe materials: how to identify the pipes in your home
Ten supply and drain materials side by side, where to look for each, and what a sighting does and does not tell you.
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Written by HyrePlumber Research Desk Primary-source research and fact checking
The short answer
Look where pipe is exposed: at the water heater, under sinks, in a basement or crawlspace, and at the water meter. The joints identify a material fastest.
Soldered means copper, threaded metal means galvanized steel, crimp rings mean PEX or polybutylene, and glued sockets mean CPVC, PVC or ABS. What you see is a sample: pipe inside the walls can differ.
What should you know before you identify a pipe?
The water heater, sinks, basement and meter are the easiest places to replace, so they may not match the walls.
A joint names a material faster than a length of pipe does. Photograph both.
It tells you what to look for. Seeing the pipe tells you what is there.
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How do the ten pipe materials compare?
A starting point for what to look at, not a verdict on what is behind the drywall. The first six carry supply water under pressure; the last four are drains.
| Material | Looks like | Joints | How it fails |
|---|---|---|---|
| Copper (supply) | Rigid reddish-brown to dull green metal, thin wall; a magnet does not stick | Soldered, with a silver-gray fillet | Pinholes from water chemistry, velocity or stray current; weeping solder joints |
| Galvanized steel (supply) | Rigid dull gray metal, thick wall; a magnet sticks | Threaded | Rust scale narrows the bore from inside; pressure falls, then threads leak |
| Lead (service line) | Dull gray soft metal, at the meter or where water enters; a magnet does not stick | Wiped, bulb-shaped joints or compression fittings | Can release lead into water; identify it with EPA’s penny-and-magnet check |
| Polybutylene (supply) | Flexible gray, blue or black plastic; can carry a PB2110 stamp | Crimped metal rings over inserts | Fittings and pipe fail, sometimes without warning |
| CPVC (supply) | Rigid cream, tan or light gray plastic, printed CPVC | Glued (solvent-welded) sockets | Turns brittle with age; cracks at or near fittings |
| PEX (supply) | Flexible plastic, red, blue or white, printed with its type | Crimp, clamp or expansion rings | Fittings, mechanical damage, rodents or sunlight exposure |
| Cast iron (drain) | Heavy black or rust-brown metal, wide; a magnet sticks | Hub and spigot, or banded no-hub couplings | Scale and corrosion along the bottom of the bore |
| Orangeburg (drain) | Dark fiber pipe, buried between the house and street | Push-together | Deforms oval and closes; found by a camera, not by eye |
| ABS (drain) | Rigid black plastic | Glued with black cement | Cracks from impact, poor joints, sags on long runs |
| PVC (drain) | Rigid white plastic, can show a purple primer ring | Glued with primer and cement | Cracks, poor joints, sags; buried lines settle or take roots |
Black steel pipe with threaded joints, running to a furnace, water heater burner or range, is likely gas pipe, not water pipe. Leave it alone; see the safety section below.
Where should you look for exposed pipe?
Take a flashlight and a phone to four places. Photograph the pipe, the fittings and any printed markings.
Hot and cold lines sit side by side. Heater connections are replaced with the heater, so they may not match the house.
You see the supply stops and risers, and the trap, which is drain material.
Long horizontal runs here are the closest look at what the house was plumbed with.
The service line entering the house. It can be a different material from everything after it, including lead.
Which pipes get mistaken for each other?
These pairs are confused because they share a color. The joint and a magnet separate them.
| Mistaken pair | How to tell them apart |
|---|---|
| Polybutylene and gray CPVC | Polybutylene is flexible with crimped rings. CPVC is rigid with glued sockets. |
| Polybutylene and PEX | Both flex and both crimp. PEX is color-coded and printed with “PEX”; polybutylene can carry a PB2110 stamp. Have a plumber confirm in person. |
| Galvanized steel and lead | Both look dull gray. A magnet sticks to galvanized steel and not to lead. EPA’s Protect Your Tap check walks through it with a penny or key and a magnet. |
| Galvanized and black iron | Both are threaded steel. Black iron is gas pipe. If it runs to a furnace, water heater burner or range, treat it as gas. |
| ABS and cast iron | Both are black. Cast iron is heavy, cold and magnetic; ABS is light plastic. |
What does each material mean for you?
Identification changes what is worth checking next. It does not produce a verdict on the house.
It fails by closing up, so patching one length does nothing for the rest of the run. That is a repiping conversation.
One pinhole is a repair. A third in the same house within a couple of years points at the system and its water chemistry.
EPA: “Lead in drinking water irreparably harms children and adults.” Ask your water system for its public lead service line inventory. Replacing the service line is separate from a repipe.
Confirmed polybutylene is treated as a replacement case. Confirm it by sight, in more than one place, before anyone quotes.
Old CPVC does not like rough handling. Some sealants, spray foams and thread compounds can harm it, so tell anyone working near it.
Long runs with few joints mean less to fail inside a wall. Keep it out of sunlight.
Both fail out of sight. A camera shows which sections have failed, which turns a whole-line worry into a decision about sections. See sewer line repair.
Durable. On buried lines the ground causes the failures: settlement, roots and crushing. Whether the two can be joined is a local code question.
How do you identify a pipe, step by step?
The pipe material identifier asks these questions in order if you would rather answer than read.
Flexible supply pipe is PEX or polybutylene. Rigid is metal, CPVC or one of the drain plastics.
Tap it. Metal rings or thuds; plastic knocks lightly.
It sticks to galvanized steel, black iron and cast iron. It does not stick to copper or lead.
Soldered is copper. Threaded is steel. Crimp or expansion rings are PEX or polybutylene. Glued sockets are CPVC, PVC or ABS.
Plastic pipe and rigid copper carry printed markings: the material, type or schedule.
Note the location. Different materials at different points mean the house was worked on in sections, which is itself the finding.
What should a pipe inspection report say?
When the answer matters, because you are buying the house or deciding on a repipe, get the plumber’s findings in writing. Walls hide the rest.
Water heater, sinks, basement or crawlspace, meter, and anywhere opened.
Supply and drain, named, with photos.
Its material at the entry, and whether it could be lead.
Corrosion, pinholes, scale, sagging, past repairs, and where materials change.
Static pressure at a hose bib and whether a pressure-reducing valve works.
For the main drain: which sections, how much bore is left, and where roots enter.
The runs inside finished walls, stated plainly.
Which pipes should you not touch?
Identifying pipe means looking, photographing and using a magnet. It does not mean opening anything.
Threaded black iron or flexible yellow-coated tubing running to a burner is gas. If you smell gas, leave the house first, use no switches, phones or flames inside, and call 911 and the gas utility from outside.
Do not cut, sand or scrape it. EPA’s Protect Your Tap guide shows the penny-and-magnet check, and your utility can say what its records show.
Do not flex or tighten old galvanized or CPVC joints to test them. Note the spot and show a plumber.
Check several points, then decide what needs a plumber.
One sighting proves one point. Look at all four places and note where they disagree. If you are buying the house, facing a second leak in a year or deciding on a repipe, ask a plumber to inspect in person, and a camera for any main drain that has blocked more than twice.
What to ask a plumber who inspects your pipes
Where did you look, and can you show me?
Could any of it be lead?
What does that say about past repairs?
Is there a working pressure-reducing valve?
Has anyone run a camera down it?
And what would it take to find out?
What to have ready before an inspection
Pipe, fittings and markings, labeled by location.
As a prompt for what to check, not a conclusion.
Leaks, remodels and past plumbing work you know of.
From its public lead service line inventory.
How often the main line has blocked, and what was done.
Where does pipe identification go wrong?
Heater connections are replaced with each heater. Copper there says nothing about the walls.
Materials overlapped by region and builder, and houses get repiped in sections without records. A year tells you what to look for.
Gray CPVC and other plastics get mistaken for it. Check the joints and have a plumber confirm in person.
The pipe at the meter can differ from everything after it. That is where lead is found.
Orangeburg and scaled cast iron respond to cleaning for a while, then close again. Repeated blockages call for a camera.
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Questions
How do I find out what pipe my house has?
Does the year my house was built tell me what pipe it has?
How do I recognize polybutylene?
How do I check for a lead service line?
What is Orangeburg pipe?
Do I need to replace cast iron drain pipe?
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