Two old metals turn up constantly in Longview houses, and people mix them up all the time. Galvanized steel carries water into the house. Cast iron carries it back out. They sit in different parts of the building, they fail in completely different ways, and one of them is far more urgent than the other depending on what stage it has reached.
What follows is how to work out which you have, what each one does as it wears out, and why the year the house was built is a starting point rather than a verdict.
Galvanized steel, and how it closes itself off
Galvanized is threaded steel pipe with a zinc coating applied to the inside to keep the steel away from the water. It was the standard supply material for decades, and it works exactly as intended until the zinc is used up. After that the bare steel underneath begins to rust, and rust does not wash away down the line. It builds up on the pipe wall in layers.
The result is a pipe that gradually strangles itself. Cut a long section of old galvanized in half and the opening left in the middle can be startling, with the rest of the diameter packed solid with scale. That is why a house that had good pressure when the family moved in has weak pressure at the far bathroom thirty years later, without anyone being able to name the year it changed.
Its symptoms are consistent. Pressure that fell off slowly rather than suddenly. Rusty or brown water from a fixture that has been sitting overnight, clearing after a minute of running. Hot water that swings hard when somebody flushes or starts the washer, which is a volume problem rather than a heater problem. And then, later, pinhole leaks showing up in different places, which is the pipe telling you the whole run has reached the end.
Cast iron, and how it thins from the bottom
Cast iron is drain pipe. It is heavy, dark gray, dull sounding when you tap it, and it was used under floors and out to the yard for generations because it lasts a very long time. It does eventually wear out, and the way it does is the part that catches people.
Waste water sits in the bottom of a drain line rather than filling it, so the bottom of the pipe is where corrosion concentrates. Cast iron rots from the channel upward. The top of a section can look perfectly sound while the invert underneath has thinned or gone entirely. You cannot judge it by looking at the outside, which is why we would rather put a camera down a line than tell you what is probably there.
It also scales inward as it ages, and rough interior walls catch what smooth ones would pass. That is why an old cast iron line clogs more readily than newer pipe of the same diameter. Its symptoms are slow drains across more than one fixture, gurgling, recurring backups, and sometimes odor. Where it has cracked or a joint has offset, roots find the opening.
Working out what you actually have
You can settle most of this yourself in a few minutes without opening anything.
Look where pipe is already visible: under sinks, at the water heater, at the meter, at the washer connections, and in a crawl space if the house has one. Galvanized supply is dull gray, threaded, and magnetic. Copper is unmistakable. PEX is flexible tubing, usually red, blue or white. CPVC is rigid cream colored plastic.
For drains, look at what leaves the fixtures and where you can see pipe running below the floor. Cast iron is heavy dark metal with a rough surface and no threads at the joints, hubbed rather than screwed together. Modern PVC drain pipe is white or off white plastic and obvious by comparison.
The most informative thing you can find is a mixture. Copper or PEX at the kitchen and galvanized at the back bathroom means a partial replacement stopped somewhere, and where it stopped is usually where the trouble waits.
What you cannot see this way is anything under a slab, and that is precisely where the oldest pipe usually is. A camera answers the drain side. Our plumbing inspection work covers the whole picture in one pass.
Why the build year is not the answer
Age tells you what was probably installed. It does not tell you what condition it is in now, and the gap between those two is wide enough that we would never quote off a build date.
Water chemistry drives a lot of it, along with how the house has been used and whether anybody worked on it along the way. We have opened walls in houses of the same era on the same kind of street and found one system with real life left and another consumed.
The ground has a hand in it too. Clay soil in this county gains volume in a wet season and loses it in a dry one, and it does that year after year underneath everything buried in it. Pipe has no way to take up that difference, so stress accumulates wherever a run is held at one end and moved at the other. Two identical cast iron lines can end up in different shape purely because of what the earth around each one did.
Housing stock compounds it. Postwar ranch construction and newer slab subdivisions sit near one another here, and the 1980s and 1990s neighborhoods bring polybutylene, which fails suddenly and which insurance carriers have opinions about. The material question is genuinely per house.
What we do with the answer
Neither material is automatically a replacement, which is worth saying plainly, because there is a version of this trade where every old pipe becomes a repipe quote.
On the supply side, a single leak in an accessible spot with sound pipe either side of it is a repair, and we will do it as one. Where the pipe we cut into looks like the pipe next to the last leak, patching has become paying in installments for a job you will end up doing anyway. We say that out loud rather than letting somebody find out one leak at a time. Our repiping page covers how that gets scoped when it is the right call.
On the drain side the camera decides. A line that is scaled but structurally sound can often be cleaned back toward its original diameter, and that is a maintenance job rather than an excavation. A line with a break, a belly, or a section rotted through is a different conversation, and sewer line repair here in Longview is often a spot repair rather than a full replacement once we can see exactly what failed and where.
The two systems fail on their own schedules, so we keep the decisions separate. The one time it makes sense to do both together is when a slab is already open or a crawl space is already accessible, which saves a second round of everything.
Where a drain problem starts looking like a clog
Old cast iron produces a specific pattern that is easy to misread. A drain clears, works fine for a while, then backs up again, and the cycle repeats on roughly the same interval. Clearing it each time treats the symptom and tells you nothing.
A drain that stopped once is a clog. A drain that clogs every spring is a line with a belly, roots, or a rough interior catching what passes. That distinction is worth insisting on, and why our drain cleaning work here includes a camera rather than just cabling it and driving away.
Questions we get about old pipe
Q. Is galvanized pipe dangerous or just inconvenient? Mostly it is a performance and reliability problem: pressure falls, discolored water shows up, and eventually leaks start. Where old galvanized was joined to lead components at some point in a system’s history, that is a separate question worth having answered, and looking at what you have will settle it either way.
Q. How long does cast iron drain pipe last? A long time, and the honest answer is that it varies too much to put a number on for your house specifically. Waste chemistry, ground movement, how much use the line got, and whether roots ever found a joint all change it. Two houses on the same street can be in different condition. A camera tells you where yours stands rather than guessing from the era.
Q. Can I tell what I have without a plumber? Largely yes, for the parts you can see. Galvanized is dull gray threaded steel and holds a magnet. Cast iron drain pipe is heavy dark metal, hubbed rather than threaded. Plastic and copper are obvious. What you cannot check yourself is anything under the slab, and that is where the oldest pipe usually is.
Q. My pressure dropped suddenly. Is that the galvanized? Probably not by itself. Scale builds gradually, so galvanized causes a slow decline over years. A sudden drop points at something else: a failed pressure regulator, a partially closed valve, a supply line problem, or a leak large enough to matter. It is worth checking promptly because a sudden change usually has an active cause.
Q. Do I have to replace everything at once? No. Supply and drain are separate systems that wear out on separate schedules, and work can be staged. What we would rather you not do is repeatedly patch a system that is clearly finished, because the accumulated repairs get you to the same place with less to show. We will tell you which situation you are in.
Find out what is behind the wall
If the pressure at the back of the house has been slipping, or a drain keeps coming back around, the useful next step is somebody with a flashlight and a camera telling you what is actually there.
Call 903-570-3051 and describe what the house is doing, or send the details over. Stephen is a licensed Master Plumber and the one who answers. There are finished jobs in our gallery, and everything we handle here is on our Longview page. You get a real price before we start, and we will tell you when the pipe has years left as readily as when it does not.