"The city handles sewer lines" is one of the most expensive myths in homeownership. In most of the country, you own the sewer lateral - the pipe running from your house to the city main - including, very often, the stretch under the sidewalk and street. When it clogs, cracks, or collapses, the bill is yours.
This guide draws the ownership map foot by foot, explains who pays when a backup makes a mess, decodes the two very different insurance products that cover sewer problems, and makes the case for the one inspection every home buyer should demand.
The Myth: "Sewers Are the City's Problem"
The city owns and maintains the main - the large pipe running down the street - and everything upstream of it is private property in most jurisdictions. That private pipe is the lateral, and it's typically the oldest, least-inspected, most root-attacked plumbing a house has. Homeowners discover the ownership rules at the worst possible moment: standing in a flooded basement, learning the word "lateral" from a claims adjuster.
The Ownership Map: House to Main, Foot by Foot
Upper lateral, lower lateral, and the tap
The upper lateral runs from the house to the property line; the lower lateral continues from property line to the main; the tap is the connection point itself. The pipe is continuous - the names exist because responsibility can change along it.
The three common models
Cities draw the line three ways: you own to the property line only; you own to the curb or cleanout; or - the most common and least expected - you own all the way to the tap at the main, street pavement included. Your public works department or sewer utility will tell you which model applies; know it before you need it.
Easements: your pipe under ground you don't control
Laterals sometimes cross neighboring parcels or public right-of-way inside an easement. The pipe stays your responsibility; the digging rules get more complicated and more expensive. Shared laterals - two houses, one pipe, common in older neighborhoods - add a co-owner to every repair decision, and the sharing agreement (if one was ever written) lives in the property records. Worth discovering before the backup, not during.
What Your Pipe Is Made Of - and Why It Matters
Age predicts material, and material predicts failure style. Clay (common pre-1970s) lasts a century structurally but invites roots at every mortared joint. Cast iron (1950s-1980s) rusts and scales from the inside, narrowing like an artery. Orangeburg - tar-impregnated wood fiber from the postwar years - deforms and blisters, and every camera operator who finds it says the same word: replace. PVC (1980s onward) is the boring, root-resistant good news. Knowing your era tells you what the camera will probably find.
Backups: Who Pays for the Mess
Blockage on your side
If the clog or break is in the lateral, cleanup, repair, and everything ruined in the basement is yours - unless you carry the right endorsement (below). The camera inspection is what establishes where the failure sits, which makes footage evidence, not upsell.
The surcharged city main
When the city main backs up into homes, municipalities can be liable - but claims run through strict notice rules: report in writing, fast, on the city's form, within its deadline. Miss the procedure and valid claims die. Photograph everything, file immediately, and keep the plumber's finding that the blockage was in the main.
The Insurance Nobody Reads Until It's Too Late
Two different products
Water/sewage backup endorsement covers the damage - the ruined basement - when sewage comes up your drains; it's a cheap add-on to homeowners policies and absent by default. Service-line coverage covers the pipe - excavation and repair of the lateral itself. They are separate endorsements answering separate disasters; plenty of homeowners buy one believing they bought both.
The mailer warranties
Those official-looking sewer-warranty letters are real products with real fine print: coverage caps that may not survive a deep excavation, waiting periods, and exclusions for pre-existing damage - which, on a 70-year-old clay line, is a large exclusion. Compare their cap and premium against a service-line endorsement from your own insurer before signing anything from an envelope.
Cleanouts: The Free Insurance You Already Own
A cleanout is the capped access point that lets a cable or camera enter the lateral without going through your house. Homes that have one get faster, cheaper service on every sewer visit forever; homes without one pay a premium every single time, or fund the retrofit. Find yours - usually a capped pipe near the foundation on the street side - and never landscape over it.
Buying a House? Scope the Sewer First
A pre-purchase sewer scope - a camera run of the lateral - costs a fraction of one percent of what lateral replacement costs, and standard home inspections do not include it. On any house older than 30 years, or younger ones with mature trees, it's the highest-leverage inspection money in the transaction: roots, offsets, bellies, and Orangeburg all become negotiating items instead of year-one surprises.
When the Lateral Fails: Repair, Line, or Replace
A localized break can take a spot repair. A structurally sound but leaky or root-prone line can often be lined - cured-in-place pipe (CIPP) builds a new pipe inside the old one with minimal digging. Collapsed or badly deformed pipe means excavation and replacement, at trench or trenchless pricing. Which one applies is exactly what camera footage decides, and lateral work is precisely the job to bid three ways - methods and prices vary enormously. The top-rated plumbing companies handle laterals, liners, and the city paperwork that comes with them.