Why draining sinks do not prove the sewer is clear
A standard home inspection runs plumbing fixtures for a few minutes during the walkthrough. Flushing a toilet uses 1.6 gallons of water, which will easily drain through a line that is 80% blocked by roots or sitting half-full of standing sludge.
Real plumbing problems appear when a household moves in and runs laundry, showers, and dishwashers simultaneously. By running a self-leveling color video camera through the line, an inspector evaluates pipe grade, joints, and physical defects before you finalize the purchase.
Common sewer pipe materials in Western Washington
The age of the home determines the pipe material buried in the yard. Each material has distinct failure points in Puget Sound soils.
Concrete and vitrified clay tile (pre-1970s)
Common in older neighborhoods throughout Tacoma, Olympia, Puyallup, and Centralia. These pipes were installed in short 3-foot to 4-foot sections with mortared joints. Over decades, tree roots from Douglas firs, cedars, and maples push into the joints to reach water, eventually cracking the pipe body.
Orangeburg pipe (1940s to 1970s)
Made from wood pulp fiber soaked in coal tar pitch. Orangeburg pipe has a structural lifespan of roughly 30 to 50 years. Under ground pressure and moisture, it blisters inside, flattens into an egg shape, and eventually collapses completely.
Cast iron (1950s to 1970s)
Subject to interior corrosion from sewer gases, known as tuberculation. Rust buildup catches toilet paper and solid waste, causing recurrent clogs. Over time, the bottom of the cast iron pipe corrodes entirely, dumping sewage into the soil beneath the house or lawn.
Modern ABS and PVC plastic (1980s to present)
Plastic pipes do not rust or rot, but they are not immune to failure. Heavy equipment driving over backfilled trenches can crush or crack plastic lines. Ground settling also causes low spots, known as pipe bellies, where waste pools and creates chronic blockages.
What sewer scope cameras uncover
| Defect | What it means | Typical remedy |
|---|---|---|
| Root intrusion | Roots enter joints or cracks, catching solids and creating total line blockages. | Hydro-jetting maintenance ($400-$800) or pipe relining ($7,000-$12,000). |
| Pipe belly (sag) | A low section of pipe where water and solids sit instead of draining by gravity. | Excavation and regrading if standing water is deeper than half the pipe diameter. |
| Offset joints | Two pipe sections shift out of alignment due to soil movement, catching waste. | Spot repair excavation or trenchless bursting. |
| Collapsed Orangeburg | Walls have flattened or broken under soil weight, blocking flow. | Full lateral replacement ($7,000-$15,000+). |
| Construction debris | Rocks, grout, or mortar left in lines during new home construction. | Mechanical clearing or builder warranty replacement. |
The municipal street repair trap in Washington
In most Washington municipalities—including Olympia, Lacey, Tumwater, and Tacoma—the homeowner is legally responsible for the private side sewer all the way to the city main line tap. This responsibility includes the portion of pipe running under public sidewalks and roads.
If a sewer lateral collapses beneath the street, the homeowner must pay for municipal right-of-way permits, traffic control, trenching, and road restoration. Those municipal requirements quickly escalate a standard $5,000 repair into a $20,000+ project.
Negotiating sewer repairs with NWMLS Form 35R
In Washington, a sewer scope is conducted under the NWMLS Form 35 inspection contingency. If the camera reveals significant defects, the buyer has three options under Form 35R:
- Request that the seller complete repairs using a licensed utility contractor prior to closing.
- Request a financial credit or purchase price reduction to cover the repair cost.
- Terminate the transaction and receive a full refund of earnest money.
Having a video recording and written inspection report gives buyers concrete evidence during contract negotiations, preventing surprise expenses after moving in.
Related inspection guides
Review our guide on what actually fails a home inspection in Washington State or learn more about our dedicated sewer scope video inspection service.