Before PVC: What Irrigation Pipe Actually Was
PVC pipe has only been standard in residential irrigation for about 60 years. Before that, we used galvanized steel, copper, clay, and some stuff that will surprise you.
PVC is newer than you think
If you started doing irrigation work in the last 30 years, you probably think of PVC as "the normal kind of pipe." It is cheap, it is easy to cut, it glues together with a primer and a can of solvent cement, and you can have a zone run in the ground in under an hour.
PVC has only been widely used in American residential irrigation since the early 1970s.
Before that, irrigation pipe was galvanized steel or copper, and you installed it with a pipe wrench, a threader, and a lot of patience. A 20-zone residential install that takes a modern contractor two days would have taken a 1960s contractor two weeks. Every joint had to be threaded and teflon-taped. Every fitting had to be wrenched on by hand. Every mistake meant cutting out a section and re-threading it.
When PVC arrived, it changed everything — but not overnight. A lot of older contractors did not trust it at first, and some of them had reasons.
What people used before
Galvanized steel was the default for most residential irrigation from roughly 1920 to 1970. It was strong, it did not rot, and you could find a plumber anywhere in America who knew how to work with it. The problem was that galvanized steel rusts from the inside out. The zinc coating protects the outside of the pipe, but the inside is exposed to water and slowly corrodes. Over 20-30 years, the rust builds up until the inside diameter of a ¾-inch pipe is barely ½ inch. Pressure drops. Flow rates crash. And when you try to replace it, the threaded joints are usually rusted solid and you end up replacing the whole run.
Every irrigation contractor over 50 has stories about cutting out galvanized lines that had been buried since the 1950s and finding them nearly choked closed. This is not a theoretical problem — it is still out there in older neighborhoods, waiting to surprise someone.
Copper was used in higher-end residential installs. It was expensive, it did not rust, and it lasted forever. Copper is still used today in a few specific situations — mostly above-ground main lines in freezing climates where flexibility matters. But the price went up every decade, and by the 1980s copper had priced itself out of almost all residential irrigation work.
Clay and concrete pipe were used in agricultural irrigation well into the 20th century. Large-diameter clay pipe for drainage is still around. Concrete pipe — yes, poured concrete, in sections, cast by the contractor on site using special forms — was used for irrigation main lines on big agricultural properties in the American Southwest from roughly 1900 to 1950. Some of these lines are still in service. They are slowly being replaced, but the sheer cost of digging them up and replacing them means a lot of farms are still running on 1920s concrete.
Redwood was used for flumes and open channels in the western US, especially in the lumber and mining industries. Not pipe exactly, but a way to move water from point A to point B. Some redwood flumes are still in service in California and Oregon, though they are getting rare. Redwood is surprisingly durable when it stays wet constantly — the trouble comes when it dries out, because that is when the wood splits.
Lead pipe was used for small-diameter service lines in American cities until the 1960s. For obvious reasons we do not use it anymore. But if you are ever working on a property built before 1960 and you find a service line that looks grayish-white and bends easily, that is lead. Do not reuse it. Cap it and run a new line.
What changed in 1970
PVC was invented in the 1920s and commercialized for municipal water and sewer use in the 1950s. But the solvent cement systems that make modern PVC joints quick and reliable did not really mature until the late 1960s, and the price of PVC did not come down to residential-affordable levels until about 1970.
Once that happened, the switch was fast. By 1975, most new residential irrigation installs in the American West were using PVC. By 1985, galvanized was almost extinct in new installs — only specialty situations (freeze-prone mainlines, industrial applications) still used it. By 1995, entire generations of installers had never seen a pipe threader.
The advantages were obvious. Cheaper material. Faster installation. No rust. Glued joints that never came loose. Lighter to carry. Easier to cut. The only real trade-off was that PVC becomes brittle after years of UV exposure, so you have to bury it or paint it if it is going to sit above ground. For buried irrigation, this is not a problem — PVC can last 50+ years underground without degrading.
The new kid: PEX and polyethylene
PVC is no longer the newest kid in the shop. Polyethylene pipe (poly, PE) has been used for drip irrigation and agricultural main lines since the 1960s — it is the black flexible stuff that comes in coils. And PEX (cross-linked polyethylene) has been used for potable water in the US since the 1980s and is now showing up in some specialty irrigation applications.
Neither has displaced PVC for the main job of residential irrigation. PVC is still cheaper, still easier to work with for rigid fittings, and still the industry default. But PEX has some advantages in freezing climates because it can expand without cracking when water inside it freezes. In 50 years, it is possible that PEX will be the new default — or it is possible PVC will still be running the show.
What you might still run into
If you are working on an older property, here is the quick identification guide:
- Threaded joints, gray metal, heavy — galvanized steel. Expect corrosion. Replace whole runs.
- Soldered joints, warm copper color — copper. Still good if it is not green with oxidation. Can usually be left in place.
- Thick-walled white pipe, glued joints — standard PVC. Normal.
- Thick-walled gray pipe, glued joints — Schedule 80 PVC or CPVC. Used where extra strength or heat resistance was needed. Still good.
- Flexible black pipe, hose clamps or compression fittings — polyethylene. Normal for drip systems. Still good.
- Gray-white, soft, bends easily, very old — lead. Do not reuse. Cap and run new.
And if you find concrete pipe, wood flumes, or clay tile — take a picture before you touch it, because you are looking at a piece of history.
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Sources: Wikipedia articles on Polyvinyl chloride, Galvanized steel, Polyethylene, and PEX (CC BY-SA 4.0). EPA documentation on lead service lines (public domain). Historical information on Western US redwood flumes and concrete pipe from US Bureau of Reclamation public records.