Service line coverage, also called underground utility coverage, is for the lines running from your house to the street connection. It is for any service underground that becomes rotted, decayed, breaks and is good for coverage up to $10,000! This applies to a home or a landlord who has a 1 to 4 family property. Why 1-4 family properties? Because those are considered a "personal lines" policy much like your homeowners insurance is a personal lines insurance policy.
So far, no insurance company has come out with this insurance policy endorsement for commercial property. I don't think it will either because those properties tend to have bigger service lines coming into the building. For example, a home's sewer line might be 2" in diameter but a commercial building could be 4" or greater. In addition, most insurance companies use a 3rd party - like Hartford Steam Boiler - to underwrite this coverage for them. So instead of the insurance company having these claims on their books, the 3rd party has the claims.
Do you have service line coverage on your home?