Do I have Orangeburg sewer pipe, and how long does it last?

What Orangeburg is

Orangeburg is the trade name that stuck to bituminised fibre pipe: layers of wood pulp pressed together and saturated with coal-tar pitch. It was light, inexpensive to make, easy to cut with a handsaw, and during and after the Second World War it was often the only sewer pipe a builder could get. Seattle's postwar boom — the ramblers of Lake City, north Ballard, the Delridge side of West Seattle, and the first waves of Shoreline and Lynnwood — was built on it. Production stopped in the early 1970s once PVC and ABS arrived.

How it fails

Fibre pipe has no rigid structure of its own; the pitch holds it in shape. Over decades, soil load and moisture soften it. The crown flattens and the pipe goes oval, which cuts capacity and gives roots a seam to work. Water gets between the layers and they delaminate, so the inside wall blisters and sheds fibres that catch debris. Eventually the crown drops and the pipe closes. The whole process is quiet; the house just needs clearing more and more often, and each cable pass takes a little more of the wall with it.

The manufacturers' own expectation was roughly 50 years in good conditions. Anything installed in Seattle is now 55 to 80 years old, and the wet, root-heavy soils of the Puget Sound lowlands are not good conditions. Orangeburg that old is often no longer round.

Telling it from clay and concrete

Why the usual fixes do not work on it

• Cabling cuts into the soft wall and accelerates delamination. Many Orangeburg lines are finished off by the third or fourth cleaning.
• Jetting at full pressure can punch through blistered wall.
• Lining needs a host pipe that will hold its shape while the liner cures and afterward. An ovalised, softening host does not, and a liner installed into it may deform with it or leave a void behind it.

Replacing it

Orangeburg is a replacement material, and the good news is that the replacement is usually trenchless. Pipe bursting pulls a new HDPE pipe through the old route, breaking the fibre pipe outward as it goes; it needs a pit at each end rather than a trench along the run, which can leave most of the yard undisturbed. Where the line is shallow, short and under open ground, a conventional open-trench replacement is sometimes simpler. The lining vs. bursting article covers how that decision is made; for Orangeburg it usually comes down to bursting versus digging.

What to do if you suspect it

1. Check the house's construction date. Between 1945 and 1972 is the window.
2. Get a camera inspection and ask specifically what the pipe material is and whether the bore is still round.
3. If it is round and intact, plan and budget. If it is ovalised or blistering, schedule the replacement before it schedules itself.
4. Pull the city's side sewer permit records; sometimes a previous owner replaced part of the run and only a section is still fibre.