Does my building need a sewage ejector or lift station?

It comes down to elevation. The 2024 International Plumbing Code (IPC), which Phoenix adopted in 2025 alongside the 2024 Uniform Plumbing Code, has a name for drains that can't reach the sewer on their own. It calls them a building subdrain: "that portion of a drainage system that does not drain by gravity into the building sewer."

IPC Section 712.1 says what happens to that water. Building subdrains "that cannot be discharged to the sewer by gravity flow shall be discharged into a tightly covered and vented sump from which the liquid shall be lifted and discharged into the building gravity drainage system by automatic pumping equipment." In other words, the low fixtures drain into a sealed pit, and a pump lifts the waste up to a pipe that can then run downhill.

Common reasons a commercial building ends up with one:

• A basement or below-grade level with restrooms, a break room sink or floor drains.
• A building pad set lower than the sewer main in the street, which happens on sloped lots and in older infill sites.
• A tenant space added below the building drain, such as a restroom built into a lower level during a remodel.
• A site with several buildings that can't all reach the public sewer by gravity, which moves the job from one pump to a site lift station.

Arizona's desert pads are mostly slab on grade, so basements are less common here than back East. That's why many Valley property managers never deal with a sewage pump until they buy or lease a building that has one.

The IPC is specific about the parts. Under Section 712, a building sewage pump system needs:

1. 1A sealed, vented pit. The sump pit must be at least 18 inches across and 24 inches deep, have a gastight removable cover set no more than 2 inches below the floor, and be vented under the code's venting chapter (712.3.2).
2. 2Only the drains that need it. In new buildings the sump "shall not receive drainage from any piping within the building capable of being discharged by gravity to the building sewer" (712.1). Fixtures that can drain by gravity must do so.
3. 3A check valve and a full-open valve on the discharge pipe, reachable for service, above the sump cover or in an access pit (712.2).
4. 4A pump sized for solids. A pump that takes toilet waste must pass spherical solids up to 2 inches; other sewage pumps must pass 1/2 inch solids. Grinder pumps get an exception with a smaller discharge opening (712.4.2).
5. 5Automatic operation. The pump must "automatically discharge the contents of the sump to the building drainage system" (712.4), and the level control must keep sewage from rising within 2 inches of the inlet pipe (712.3.4).

One more code rule sits right next to these. If fixtures are on a floor lower than the manhole cover of the next upstream manhole on the public sewer, IPC 714.1 requires a backwater valve to protect them from sewage flowing back in. A building low enough to need a pump is often low enough to need that valve too. Our page on when a backwater valve is required covers it.

The pit's vent follows its own rule. IPC 906.5.1 says "drainage piping below sewer level shall be vented in the same manner as that of a gravity system," and it sizes the sump vent by how many gallons per minute the pump discharges. A capped or missing vent is how sewer gas ends up in a basement office.

Cities amend these sections, and a Phoenix project may be designed to the UPC instead, which numbers its sump rules differently. The approved permit plans for your building are the final word.

This is where the rules change hands.

A sewage pump inside one building, feeding that building's own drain, is building plumbing. It is covered by the plumbing code and the city's building permit.

A system that collects sewage from across a site and pushes it to the public sewer is a different animal. Arizona's rule for sewage collection systems, A.A.C. R18-9-E301 (the ADEQ 4.01 General Permit), covers a system that includes a manhole, a system that "includes a force main or lift station serving more than one dwelling," and larger systems past the point where design flow reaches 3,000 gallons per day. Those need an engineered design, a Construction Authorization before building and a Discharge Authorization before use. Our page on whether a private lift station needs ADEQ approval walks through that process.

Phoenix's water and wastewater design manual describes the site version plainly: a private sewer and lift station is "a privately owned piping system designed expressly for the purpose of collecting wastewater generated within a private development site and transporting it to the public sanitary sewer system." Where your system falls between those two is a question for the design engineer and the reviewing agency, so ask before you build or expand.

If you're buying, leasing or taking over a property, a few quick checks tell you a lot:

• Look for a sealed lid in the floor of a basement, mechanical room or low level, usually with a vent pipe and a discharge pipe coming out of it. That's a sewage pump pit.
• Look outside for a buried concrete structure with a hatch, a control panel on a post or wall, and an alarm light. That points to a site lift station.
• Ask for the as-built plans and O&M manual. A permitted lift station should have an operation and maintenance manual, which the 4.01 rule requires the owner to keep.
• Check the lease or CC&Rs for who pays to run and repair it. Our guide to who owns and maintains a private lift station covers that question.

If you find one, learn what it is before it alarms. The sewage lift station basics page explains how the wet well, pumps and alarm work together, and sump pump vs ejector pump vs lift station sorts out the names.

No low drains, no pump. That's the short version. If your building does have one, it's a working part of the sewer, not an accessory, and it follows plumbing code rules on the pit, the valves and the pump.

When the drain lines leading to it are slow or backing up, that part is ordinary drain work. HQ Plumbing and Air can camera and clear commercial drain and sewer lines, 24/7, with the price given up front before work starts.