Short definition
ABS pipe (acrylonitrile butadiene styrene) is the black, rigid thermoplastic that dominates drain, waste, and vent (DWV) piping in Washington homes. It’s joined by single-step solvent cement, stays flexible at very low temperatures, and is not pressure-rated — never use it for water supply. Most Washington residential DWV systems built since the 1970s are ABS.
What it is
ABS shows up as the visible black DWV piping under sinks, behind walls, and through the attic to the roof vent. Standard residential DWV is Schedule 40 ABS, joined with ABS-specific solvent cement (single-step, no separate primer required by most codes — unlike PVC’s two-step primer-plus-cement process).
The reason ABS is dominant in the Pacific Northwest specifically: ABS stays flexible to about -40°F without becoming brittle. PVC, by contrast, gets fragile in cold attics. For unconditioned crawlspaces and attic vent runs in WA, ABS is the safer choice and that’s why the code-approved material in your house is almost certainly ABS.
Why it matters to a homeowner
Two things to know about ABS in older Washington homes:
- The 1980s “ABS rot” issue. Some lots of ABS pipe manufactured in the 1980s had quality-control problems — fines content and regrind material — that led to longitudinal cracking and joint separation over time. There was class-action litigation. Modern ABS doesn’t have these issues, but a pre-1990 home with original ABS DWV is worth inspecting at exposed joints. If you see brittle, cracked, or separated joints, you’re seeing the pattern.
- UV degradation at roof vent terminations. ABS exposed to sunlight goes brittle and crumbles over years. The fix is to paint the upper section with latex paint, or replace it with a section the sun can’t reach.
When mixing materials during a remodel, you cannot bond ABS to PVC with regular cement. Either use a dedicated ABS-PVC transition cement (where code permits) or — more commonly — a mechanical no-hub or Fernco coupling.
Common variants and what ABS is not
- ABS vs. PVC. Both are plastic DWV. ABS is black, single-cement, cold-tolerant; PVC is white or cream, two-step primer-plus-cement, more brittle in cold. Some jurisdictions allow only one in new residential work.
- ABS DWV vs. ABS pressure pipe. Standard residential ABS DWV is not pressure-rated. Don’t reuse leftover DWV pipe for water supply lines.
- Schedule 40 vs. Schedule 80 ABS. Residential DWV is Schedule 40. Schedule 80 is industrial.
Common failure modes
- 1980s ABS rot — joint separations and longitudinal cracks in pipe from that era.
- UV brittleness at exposed roof vent terminations.
- Glue failure at incorrectly cemented ABS-to-PVC transitions.
- Cracked vent termination from ladder impact or roof traffic.