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Sewer Line Size and Replacement Calculator

IPC Tables 709.1 and 710.1(1), and the size limits in Sections 716 and 717

The International Plumbing Code limits pipe bursting to sewers 6 inches and smaller and relining to sewers 4 inches and larger, both at the same nominal size. A 3 inch house sewer can be burst but cannot be relined, and no sewer can be relined where the camera survey shows it has lost its slope. Price guides quote lining by the foot without either limit. This calculator sizes the sewer from its fixtures, checks the method against the pipe, and prices the run.

Size the building sewer and check the replacement method

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A bathroom group is a toilet, lavatory and bathtub or shower in one room. Count other fixtures outside a bathroom group in the last box using Table 709.1: a lavatory 1, a bathtub or shower 2, a floor drain 2.

Specification summary

Generated from on . Reopen that address to reproduce these figures exactly.

Entered

Result

This sewer is drawn from the fixtures and run you describe above.
Building sewer, house to street

Sewer line replacement prices

Per linear foot
ItemLowHighUnit
Complete replacement$60$250per foot
Cured in place lining$90$250per foot
Pipe bursting$60$200per foot

Source: HomeAdvisor, how much does sewer line replacement cost. Last price check: September 13, 2026.

The source prints these per foot ranges in a table without saying whether they include labour, materials or restoration, and attaches no pipe size to any of them. Under IPC 717.2 lining is limited to sewers 4 inches and larger and under 716.2 bursting to 6 inches and smaller, so check that a method is allowed on your pipe before comparing its price. The same guide gives $1,388 to $5,323 for a whole replacement, $3,319 on average.

Worked example

A house with three bathroom groups, a kitchen sink, a dishwasher and a clothes washer, on an existing 3 inch sewer 60 feet long at 1/4 inch per foot, quoted for relining.

  1. Fixture units. 3 × 5 + 2 + 2 + 2 = 21 dfu.
  2. Size. Table 710.1(1), 1/4 in per ft: 3 in takes 42. 3 in, which is also the minimum for a sewer serving a water closet.
  3. Fall. 1/4 × 60 = 15 in from the house to the street connection.
  4. Relining. Section 717.2 limits it to 4 in and larger: not permitted on this sewer.
  5. Pipe bursting. Section 716.2 allows 6 in and smaller, same nominal size, HDPE SDR 17: permitted.

On this house the lining quote is for work the code does not allow on the pipe. Bursting or digging are the options. At 4 inches both trenchless methods would be open, subject to the camera survey showing no loss of slope.

The formula

Add the fixture units, then read the smallest diameter whose capacity at your slope covers them:

load (dfu) = Σ fixtures × Table 709.1 value    size = smallest diameter with Table 710.1(1) capacity ≥ load    fall = slope × length
bathroom group
5 dfu with a 1.6 gpf toilet, 6 with a larger flush
kitchen sink, dishwasher, clothes washer, laundry tray
2 dfu each
3 in
the minimum building drain serving a water closet
1/8 in per ft
the least slope Table 704.1 allows on 3 to 6 inch pipe
716.2 and 717.2
bursting 6 in and smaller, relining 4 in and larger, same nominal size

Fixture units are a load factor, not gallons. They account for the chance that fixtures discharge at the same time, which is why a sewer's capacity in units grows much faster than its cross section.

Why this page reads the code before the price

Sewer replacement searches are almost all about cost, and the cost pages compare dig, burst and line as though every method were available on every pipe.

The IPC has a section for each trenchless method, and each opens with a size limit. Together they rule relining out on a 3 inch sewer and rule bursting out above 6 inches, and relining is refused outright where the pipe has lost its slope.

The size table and the fixture unit values are read from the Texas adoption of the 2021 IPC. The prices are HomeAdvisor's, bylined and dated, and this site publishes none of its own.

Building sewer capacity and trenchless limits
Diameter, in1/16 in/ft1/8 in/ft1/4 in/ft1/2 in/ftPipe bursting (716.2)Relining (717.2)
1 1/4——11permittednot permitted
1 1/2——33permittednot permitted
2——2126permittednot permitted
2 1/2——2431permittednot permitted
3—364250permittednot permitted
4—180216250permittedpermitted
5—390480575permittedpermitted
6—7008401,000permittedpermitted
81,4001,6001,9202,300not permittedpermitted

Read 2026-09-13. IPC 2021 Table 710.1(1) and Sections 716.2 and 717.2 as adopted in Texas.

Download this table as CSV. Same cells as printed above, nothing added.

Sewer size is fixture units, and which trenchless method is legal depends on it

Table 710.1(1) sets the most drainage fixture units a building sewer may carry at each diameter and slope. Its footnote sets the floor for a house:

The minimum size of any building drain serving a water closet shall be 3 inches.

Maximum drainage fixture units on a building sewer, Table 710.1(1), with the pipe bursting and relining size limits from Sections 716.2 and 717.2
Diameter, in1/16 in/ft1/8 in/ft1/4 in/ft1/2 in/ftPipe bursting (716.2)Relining (717.2)
1 1/4——11permittednot permitted
1 1/2——33permittednot permitted
2——2126permittednot permitted
2 1/2——2431permittednot permitted
3—364250permittednot permitted
4—180216250permittedpermitted
5—390480575permittedpermitted
6—7008401,000permittedpermitted
81,4001,6001,9202,300not permittedpermitted

A 3 inch sewer at 1/4 inch per foot takes 42 units. A bathroom group with a 1.6 gallon toilet counts 5, a kitchen sink, dishwasher and clothes washer 2 each, so most houses sit well inside it. At 1/8 inch per foot, which Table 704.1 permits for 3 inch pipe, the same sewer takes 36.

The dashes are not gaps. Nothing is listed at 1/8 inch per foot below 3 inches, or at 1/16 below 8, because Table 704.1 does not allow those slopes on those sizes. The two tables agree cell for cell.

Pipe bursting stops at 6 inches, relining starts at 4

The code has a section for each of the two common trenchless replacements, and each opens with a size limit.

The replacement of building sewer and building drain piping by pipe-bursting methods shall be limited to gravity drainage piping of sizes 6 inches (152 mm) and smaller. The replacement piping shall be of the same nominal size as the existing piping.

The relining of existing building sewers and building drainage piping shall be limited to gravity drainage piping 4 inches (102 mm) in diameter and larger. The relined piping shall be of the same nominal size as the existing piping.

So a 3 inch building sewer can be burst and cannot be relined. Four to six inches can be either, above six only relined, and in every case the new pipe stays the nominal size of the old one: neither method is a way to upsize a sewer. Pipe bursting also fixes the material:

The replacement pipe shall be made of high-density polyethylene (HDPE) and shall have a standard dimension ratio (SDR) of 17. The pipe shall be in compliance with ASTM F714.

Relining has a gate before the permit. The code official reviews a recorded camera survey first, and:

Where review of the preinstallation recorded video camera survey reveals that piping systems are not installed correctly or defects exist, relining shall not be permitted. The defective portions of piping shall be exposed and repaired with pipe and fittings in accordance with this code. Defects include, but are not limited to, backgrade or insufficient slope, complete pipe wall deterioration or complete separations such as from tree root invasion or improper support.

A sewer that has settled flat or back towards the house cannot be lined. The flat run is dug up and relaid at a proper slope, and only then is the rest eligible.

Price guides do not carry either limit. The HomeAdvisor guide quoted below prices cured in place lining per foot with no diameter attached. Check the pipe size on the camera survey before comparing a lining quote with a bursting one.

Before any quote: the camera survey

Both trenchless methods start with a recorded video survey. Section 716.3 requires one before pipe bursting, noting cleanouts and the depth of connections; Section 717.3.1 requires one before relining, noting the address, cleanouts, fittings, approximate depth and the length at intervals of no more than 25 feet.

For relining, the survey is reviewed before a permit is issued, and the code official decides whether the pipe can be lined to the manufacturer's requirements. A survey showing backgrade, insufficient slope, complete wall deterioration or separations ends the lining option for those sections.

Ask for the survey file. It shows the pipe's size and condition, which are the two facts every method and every price depends on.

The source, and what differs by state

Read 2026-09-13. Texas IHB Plumbing Code 2021, Chapter 7 Sanitary Drainage, International Plumbing Code 2021 as adopted with amendments in Texas, read through UpCodes with the jurisdiction and edition stated on the page. Sections 703.4, 704.1, 710.1, 716 and 717, Table 704.1, Table 709.1 and Table 710.1(1) with its footnote.

This is the International Plumbing Code. States on the Uniform Plumbing Code size building sewers from a different table with different fixture unit values, and the IPC's pipe bursting and relining sections have no equivalent there in the same form. The UPC's text could not be read for this page. Many cities and sewer utilities also set their own lateral size and material, and some require 4 inch laterals whatever the load.

When the whole drainage system is replaced, Section 703.4 requires the existing sewer to be camera inspected for slope, breaks, obstructions and size:

Where the entire sanitary drainage system of an existing building is replaced, existing building drains under concrete slabs and existing building sewers that will serve the new system shall be internally examined to verify that the piping is sloping in the correct direction, is not broken, is not obstructed and is sized for the drainage load of the new plumbing drainage system to be installed.

Frequently asked questions

What size should a house sewer line be?
Under the IPC, at least 3 inches for any building drain serving a water closet, and large enough for the fixture units at its slope. A 3 inch sewer takes 42 dfu at 1/4 inch per foot and 36 at 1/8, which covers most houses. Many sewer utilities require 4 inch laterals whatever the load.
How many fixture units is a bathroom?
A bathroom group with a 1.6 gallon per flush toilet counts 5 drainage fixture units in IPC Table 709.1, and 6 with a larger flush. Fixtures added to the group add their own value.
Can a 3 inch sewer line be relined?
Not under IPC Section 717.2, which limits relining to gravity drainage piping 4 inches in diameter and larger. A 3 inch sewer can be replaced by pipe bursting under Section 716.2, or dug up and replaced.
Can pipe bursting make my sewer bigger?
Not under the IPC. Section 716.2 requires the replacement pipe to be the same nominal size as the existing pipe, and relining under 717.2 has the same rule. Upsizing means conventional replacement.
Can a sewer with a belly be relined?
No, under IPC 717.5 relining is not permitted where the camera survey shows backgrade or insufficient slope. The defective section must be exposed and repaired with pipe and fittings first.
How much does sewer line replacement cost per foot?
HomeAdvisor's June 2026 guide gives $60 to $250 per foot for complete replacement, $90 to $250 for cured in place lining and $60 to $200 for pipe bursting, without saying what the figures include. Its whole-job range is $1,388 to $5,323, $3,319 on average.
What slope does a sewer line need?
IPC Table 704.1 requires at least 1/4 inch per foot for pipe 2 1/2 inches and smaller, 1/8 for 3 to 6 inches and 1/16 for 8 inches and larger. The drain slope calculator works out the fall over a run.
What pipe is used for pipe bursting?
IPC 716.4 requires high-density polyethylene pipe with a standard dimension ratio of 17, complying with ASTM F714, and HDPE fittings complying with ASTM D2683.

Check these numbers yourself

How every figure here is verified: Sources & Method. Who builds this: About. Found something wrong? Tell us and it gets fixed or removed.

Figures on this page last checked against the source documents on 2026-09-13. Codes are amended locally; confirm against the edition your jurisdiction enforces.

Related calculators

Sizes and method limits are quoted from the 2021 International Plumbing Code as adopted in Texas, read on 13 September 2026. States on the Uniform Plumbing Code, and many cities and sewer utilities, set different rules for building sewers and laterals. Sewer replacement is permit work. Prices are HomeAdvisor's, not this site's.