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Plumbingaka: house seweraka: sanitary service

Building Sewer

In Plain English

The underground pipe outside a building that connects the building's drain system to the city sewer or septic tank.

Definition

The pipe that extends from the building drain at the foundation wall to the public sewer main or private septic system. The building sewer is the responsibility of the building owner and must be installed with proper slope, cleanouts, and separation from water supply lines. Material options include PVC, ABS, cast iron, and vitrified clay pipe.

Why It Matters in Bidding

The building sewer is often the dividing line of responsibility between plumbing and sitework subs, so scope gaps here are a frequent source of disputes and missed line items at bid time. Its length, depth, tie-in fees, and connection to a public main or septic system can swing the underground portion of a bid significantly.

Example

An estimator bidding a commercial tenant project prices 120 feet of building sewer from the foundation to the street main, including a tap fee, two cleanouts, and trench shoring where the run exceeds five feet of bury depth.

Related Terms

Building DrainCleanoutSanitary SewerSoil Pipe

Frequently Asked Questions

The building owner typically owns the sewer lateral up to the public main, but the trade carrying it in the bid varies. Plumbers may run it from the building, while sitework subs handle deeper excavation. Define this boundary in the scope sheet to avoid a coverage gap between subs.
Beyond pipe and fittings, price trenching, bedding, backfill, compaction, cleanouts, and any required separation from water lines. On public connections, add the municipal tap or connection fee, which can be substantial and is easy to omit because it sits outside standard material pricing.
Yes. PVC and ABS are economical and common, while cast iron or vitrified clay carry higher cost and may be required by local code or soil conditions. Confirm the specified material before pricing, since assuming the cheapest option can make a bid non-responsive or trigger a change order.

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