Pipe size, trench depth at the house, fittings and cost for a gravity sewer lateral replacement.
Estimates are planning aids, not a professional quote. Double-check quantities and product coverage — and any local code or permit requirements — before you buy.
⚠ Tapping into a public sewer main almost always requires a permit and inspection from the local sewer authority or public works department, and many require the tap cut itself to be made by a licensed contractor or a city crew — confirm before scheduling any digging.
⚠ Call 811 before digging — a sewer lateral this deep commonly runs near water service, gas and other buried utilities.
| Plumbing & Heating | $346–$468 |
| Soil & Fill | $287–$388 |
| Total | $633–$856 |
Excludes tools, delivery, tax and permit fees. Labor not included — this is a DIY materials estimate.
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About this calculator
Give the Sewer Line Replacement Builder your lateral length, the invert depth at the main, and your home's drainage fixture unit (DFU) load, and it works the job the way a plumber does: pipe diameter off a code capacity table, then the trench depth at the house worked backward from the main's invert and the minimum required fall over the run. That backward geometry is the whole job — it's the one number a tape measure at the surface can't give you.
It builds the full parts list around that sizing — SDR-35 PVC or cast-iron pipe by the stock length, bedding sand and backfill by the cubic yard, long-sweep wyes and bends, a two-way cleanout at the property line, a shear gasket at the tap, and a sewage ejector pit if a basement fixture sits below the gravity invert. This is a planning estimate for budgeting and prep, not a substitute for your local sewer authority's permit and tap-in review.
Step by step
A step-by-step walkthrough to go with your plan above. Follow the product instructions and any local code or permit requirements as you work.
File for a sewer authority permit and call 811 for utility locates before anything else — most jurisdictions also require notifying them of the tap-in cut and won't let a general contractor make that connection alone.
Get the actual invert elevation from the utility's as-built drawing or a locate, rather than assuming — this single number, combined with the run length, sets how deep the house end has to be dug.
Add up your drainage fixture units and check them against the capacity table to confirm the pipe diameter, then pick SDR-35 PVC or cast iron based on local code and any depth-of-cover requirements.
Dig the trench to the calculated depth at both ends, checking the fall continuously with a laser level so it never dips back uphill anywhere along the run.
Place the bedding sand envelope, lay the pipe on a steady, unbroken grade, and set the long-sweep wyes and bends only where the run actually changes direction.
Install the two-way cleanout at the property line and any inline cleanouts the run length requires, bringing each one up to an accessible point at or near grade.
Connect at the main with the shear gasket per the utility's standard, whether that's your licensed contractor's cut or a scheduled visit from the utility's own crew.
Backfill in the sand envelope first, then the remaining fill in compacted lifts to grade, and restore the surface — schedule the inspection before covering anything the inspector needs to see.
Equip the job
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Answers
Pipe diameter is picked from your total drainage fixture unit (DFU) load against a standard building-sewer capacity table at a 1/4 inch per foot slope. Add up your fixtures — roughly 6 DFU per full bathroom, 2 for a kitchen sink, 2 for a dishwasher, 3 for a clothes washer standpipe — and a 4-inch pipe handles up to about 216 DFU, which is essentially every single-family home. A bigger lateral only shows up for a heavy load or a shared multi-unit connection, and code sets 4 inches as the practical minimum for a dwelling regardless of how low the DFU count comes out.
It's set backward from the main, not forward from the house: take the invert depth at the main (from the utility's as-built or a locate), then subtract the fall the whole run loses at the minimum slope — about 1/4 inch per foot. A 60-foot run at that slope drops 1.25 feet end to end, so an 8-foot-deep main puts the house end at roughly 6.75 feet. Longer runs or deeper mains push that number down fast, which is why you can't just measure the depth at the foundation stub and assume it holds all the way out.
SDR-35 PVC is the standard choice for a new gravity sewer lateral in most jurisdictions — it's lighter, cheaper, corrosion-proof, and joins with a simple gasketed bell and spigot. Cast iron (hubless, no-hub) is heavier and roughly twice the material cost, but some municipalities require it under a driveway, within a set distance of the building, or where a shallow bury can't get enough soil cover to protect PVC from surface loads. Check your local code and the section your inspector will actually be looking at before ordering pipe.
Almost always, yes — connecting to or disturbing a public sewer main is regulated by the local sewer authority or public works department, separate from any general plumbing permit for work at the house. Many jurisdictions also require that the actual tap-in cut at the main be performed by a licensed contractor or the utility's own crew rather than a general contractor, and will want to inspect the bedding and slope before the trench is backfilled. Call before you dig, both for the permit and for utility locates.
An ejector pit is a sealed basin with a submersible pump that collects waste from a fixture sitting below the elevation the lateral can reach by gravity — most often a basement bathroom or laundry room added after the original lateral was set. The pump discharges up and over into the gravity line through a small pressurized force main. It needs a dedicated, GFCI-protected circuit, a check valve to stop backflow into the pit, and typically a high-water alarm, so budget for an electrician alongside the plumbing work.
Code generally requires a cleanout at the property line (often a two-way cleanout that can be rodded in either direction), at the base of the stack near the house, at every change of direction greater than 45 degrees, and at intervals not exceeding about 100 feet along a straight run. A typical single-family lateral replacement ends up with two or three cleanouts total once those rules are applied — enough that a clog anywhere along the run can be reached from the surface without excavating.