Why it is not in a standard inspection
A general home inspection does not include the sewer lateral. It is one of the most expensive components of a property and one of the few nobody checks by default.
What it costs against what it finds
A scope is a small fraction of what a lateral replacement costs. On an older Northern Utah home it is one of the highest-value checks available before closing.
When it matters most
Pre-1970 housing. Mature trees between the house and the street. Any property where the seller mentions previous drain work, which is worth understanding in full.
What to do with the result
A fault found before closing is a negotiating position. The same fault found afterwards is simply your problem.
What to ask for in the report
The recording, the distance to anything found, and a plain statement of whether the line is serviceable. A verbal summary is not much use to you in a negotiation.
Timing it properly
It needs to happen inside the inspection period, which is short. Arranging it at the same time as the general inspection is usually the practical way, and worth raising with your agent early.
What a problem is worth in negotiation
A fault found before closing is a number that can be discussed. The identical fault found three months later is entirely your expense. That asymmetry is the whole argument for doing it beforehand.
Which houses most warrant it
Anything built before about 1970. Anything with mature trees between the house and the street. And any property where previous drain work is mentioned, which is worth understanding in full rather than taking as reassurance.