Methodology
Last updated November 9, 2026
Every number on this site is either sourced or labelled as an estimate. This page explains the difference, and how a claim gets from a source document to a published page.
1. Primary sources first
Inspection and method claims follow the locally adopted plumbing code and the industry inspection standard named on the page. Liner claims follow the manufacturer's specification and the ASTM standard the liner is made to, plus the pipe diameter and condition it is rated for. Cost bands come from published US price guides, with the month checked stated on the page.
2. Cost models show their inputs
Installed cost is modelled from visible inputs: the material or equipment price, the labour and access scope (excavation, drain, electrical, permit), consumables, and a reserve for service or repair. We do not present a single "average cost" as if it were a quote; the range and what it includes are stated on the page.
3. How options are compared
We compare methods on the defect they address, the pipe material and diameter they suit, expected service life, and the excavation and restoration each requires. A method earns a recommendation for a stated defect; no contractor can buy a place in a comparison.
4. What we have not tested
We do not run a laboratory or a crew, and we do not carry out every job we write about. When a claim comes from a manufacturer document, an adopted code, a certification listing or a contractor report, we say which. We do not imply first-hand testing we did not perform.
5. Sources we work from
| Source type | What it decides | How it is cited |
|---|---|---|
| Locally adopted plumbing code | Permits, materials and inspection requirements | Section cited |
| Pipeline assessment and certification standard (NASSCO PACP) | How a camera defect is graded and recorded | Standard named |
| Liner manufacturer specifications (ASTM F1216 for CIPP) | Pipe diameter, condition limits and cure requirements | Standard and product named |
| State and local licensing boards | Which licence a repair contractor must hold | Board named, with its lookup link |
| Published US price guides | Installed cost bands | Band with the month it was checked |
When two sources disagree, the page says which one it followed and why. A figure that cannot be traced to a document is labelled an estimate, and an estimate is never presented as the price of a specific job.
6. Listings and directory data
The service-area directory is compiled from public business records: the firm's own website, its published address and phone number, and the state or local licence register named on the city page. A record is marked verified only when the name, address, phone and licence have been checked against those sources and the date of the check recorded; everything else is labelled. Where a source does not publish a ZIP code or a website, the field is left blank rather than guessed — and a firm being listed here is not an endorsement or a statement that it holds the right licence for your job.
7. Corrections
If a code, a specification or a listing changes, we update the article and its "last updated" date. Emailcontact@sewerlinelab.com with the page and the correction.