Question 1

The 'Building Sewer' typically starts at a point ___ outside the building wall.

Accepted Answer

IPC Definitions state the Building Drain extends to 30 inches exterior of the building wall. Beyond that point, it becomes the Building Sewer.

Question 2

What is the minimum size of a building sewer?

Accepted Answer

IPC 710.1 requires the building sewer to be at least the size of the building drain. While 3 inch is theoretically possible by hydraulic calculation, practically and historically most codes mandate a 4-inch minimum for the main sewer lateral.

Question 3

A cleanout is required on the building sewer at the junction with the building drain and at intervals not exceeding ___ feet.

Accepted Answer

IPC 708.1.2 requires cleanouts every 100 feet in horizontal drainage lines, including the sewer.

Question 4

Building sewers 8 inches and larger require:

Accepted Answer

IPC 708.1.3 mandates manholes for larger sewers (8 inch+) at changes of direction or grade.

Question 5

The minimum slope for a 4-inch building sewer is:

Accepted Answer

IPC 704.1 allows 1/8 inch per foot for pipes 3 inches (where approved) or 4 inches and larger. Standard practice often targets 1/4 inch, but 1/8 inch is the code minimum for 4 inch.

Question 6

No building sewer shall be installed in the same trench as water service piping unless:

Accepted Answer

IPC 603.2 allows common trenching only if this separation and shelf requirement is met to protect the water supply from sewage leaks.

Question 7

When a building sewer is installed in filled or unstable ground, it shall be made of:

Accepted Answer

IPC 306.2 requires piping in unstable ground to be supported on a concrete pad, piles, or other approved methods to prevent settling and breakage.

Question 8

Under UPC, the building sewer must have a cleanout located within ___ feet of the property line.

Accepted Answer

UPC 719.1 requires a cleanout within 2 feet of the property line (often called a property line cleanout or test tee).

Question 9

Existing building sewers may be used for new building plumbing ONLY if:

Accepted Answer

IPC 701.2 allows reuse of existing sewers only after examination and testing confirm they comply with code requirements.

Question 10

Backwater valves used in a building sewer must be:

Accepted Answer

IPC 715.5 requires backwater valves to be accessible for inspection and maintenance (cleaning).

Question 11

The connection of the building sewer to the public sewer must be made:

Accepted Answer

Connections must use fittings that direct flow (wyes/saddles) and must be gas-tight and watertight.

Question 12

For testing a building sewer with water, the static water head must be at least:

Accepted Answer

IPC 312.6 requires a 10-foot head of water for testing gravity sewer piping.

Question 13

Forced main sewers (pumped sewage) piping shall be:

Accepted Answer

Pump discharge piping must be pressure rated to handle the pump head pressure; standard foam-core DWV is generally not acceptable for pressure.

Question 14

If the public sewer is not available, the building sewer shall connect to:

Accepted Answer

IPC 701.2 requires connection to an approved private sewage disposal system (septic) if public sewer is unavailable.

Question 15

Can a building sewer run under another building?

Accepted Answer

Typically, codes prohibit running one building's sewer under another building due to maintenance and easement issues.

Question 16

Tracer wire is required for:

Accepted Answer

While mandated heavily for gas, many local amendments and good practice (often referenced in IPC 306) require tracer wire for plastic sewers to allow locating them later.

Question 17

The minimum cover (burial depth) for a building sewer is:

Accepted Answer

IPC 305.4.1 leaves the specific depth to the local jurisdiction (to be inserted in the code text) based on local frost lines.

Question 18

Mechanical joints in underground sewer piping (e.g., ferncos with shear rings) must be:

Accepted Answer

Underground couplings, especially shielded ones, need proper bedding and support to prevent the weight of the earth from shearing the pipe connection.

Question 19

Sewer lines must be laid on:

Accepted Answer

IPC 306.2.3 requires proper bedding (sand, gravel) to support the pipe along its entire length.

Question 20

In the IPC, a building sewer cleanout is required for changes of direction greater than:

Accepted Answer

IPC 708.1.4 requires cleanouts at changes of direction greater than 45 degrees.

Question 21

Relining existing sewers (CIPP) requires:

Accepted Answer

Rehabilitation of piping systems (relining) is permitted but subject to approval (IPC 716) to ensure the reduced diameter still meets flow requirements.

Question 22

Septic tanks must be sized based on:

Accepted Answer

Private sewage disposal sizing (IPC Chapter 13 or local health code) is typically based on the potential occupant load (bedrooms) and the soil's ability to absorb effluent.

Question 23

When transitioning from Building Drain to Building Sewer, the fitting used is typically a:

Accepted Answer

A cleanout is required at the junction (IPC 708.1.1), so a cleanout fitting is installed.

Question 24

Using IPC Table 710.1(1), what is the DFU capacity of a 6-inch building sewer sloped at 1/4 inch per foot?

Accepted Answer

This specific value may vary by exact table edition, but typically a 6-inch sewer at 1/4 inch slope carries approx 840 DFU.

Question 25

Leak testing of a building sewer with air requires a pressure of:

Accepted Answer

IPC 312.3 allows air tests at 5 psi for 15 minutes (though many manufacturers prohibit air testing PVC due to shrapnel risk).

Sanitary Sewer Practice Questions

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