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Check the soil around a sewer line

USDA soil survey under the address: corrosivity to iron and steel pipe, shrink-swell movement, water table. Free, no account required.

Usually 1–3 seconds. The USDA service occasionally takes longer.

How to read the result

Corrosion risk is the survey's own rating of what the ground does to buried pipe, in two columns: uncoated steel — the material family cast-iron laterals belong to — and concrete. Classes are Low, Moderate and High, defined in the USDA NRCS Soil Survey Manual, ch. 3 — risk of corrosion and shrink-swell (LEP) classes, from the soil's moisture, acidity, texture and dissolved salts. High-rated ground genuinely eats iron pipe from the outside; Low-rated ground makes “the soil destroyed your pipe” a claim worth asking to see on camera. The rating says nothing about clay, Orangeburg or plastic pipe, which do not rust.

Shrink-swell (linear extensibility) is how much the soil changes volume between wet and dry, driven by its clay. Expansive ground moves seasonally, and rigid, jointed pipe — clay tile, cast iron — takes that movement at the joints, which is where cameras find offsets and separations. We weight the value over the profile the survey records and report the class with the number behind it.

Water table is the shallowest depth the survey records groundwater in a typical year. When it stands at lateral depth for part of the year, groundwater pushes in through any bad joint (that flow is what keeps some “mystery” backups seasonal) and a repair trench may need dewatering, which shows up in excavation quotes.

Address-level vs. neighborhood estimate. Some map units — especially “Urban land” in city centers — are recorded without measured properties. When the point under the address is one of them we widen the search (400 m, then 800, 1,600 and 3,200) and report the surveyed ground around it, weighted by how much of the area each soil covers, with the radius and the share of that area that has data. City addresses hit this more often than rural ones; the result labels itself plainly when it happens.

What it does not say. Sewer Line Record is an independent reference built on public records and published sources. It is not an inspection, and nothing here states that a specific sewer line is failing, safe or code-compliant.

Full method, data provenance and the traps we hit: methodology.