Onsite and offsite describe where work sits relative to a development; an agency may define them for a particular program. They do not determine who owns or maintains a pipe. Check the utility’s service boundary, recorded easements and required permits, including for private laterals crossing public rights of way.
Where does onsite end and offsite begin?
Check the agency’s definition for the plan or program. A property boundary, easement boundary and utility service boundary are separate questions. A Water Services policy document defines a water service connection as the line running from the city's distribution main to the meter, which sits at the property line or the easement line. Phoenix's sewer code puts it in one sentence: off-site infrastructure is infrastructure necessary or beneficial to a development that is not located on the property of the development.
Here is how the two sides compare on a typical commercial site:
| Onsite | Offsite | |
|---|---|---|
| Location | Inside your lot and building | Street, alley, sidewalk area or easement |
| Examples | Fixtures, floor drains, grease interceptor, water heater, piping to the meter | Mains, taps, service lines to the property line, lift stations |
| Drawn on | Plumbing plans | Civil or engineering plans |
| Permit | Confirm plumbing/building and any easement approvals | Confirm engineering, utility and right-of-way approvals |
| Owner afterward | Check actual facilities and service terms | Check actual facilities and service terms, including private laterals |
A new restaurant's kitchen drains, floor sinks and grease interceptor are onsite. The sewer main in the street, the tap into it, and the pavement cut to reach it are offsite.
What counts as offsite plumbing work?
- Water mains and sewer mains built or extended to reach your parcel.
- Taps, the connections from your service line into the city main.
- Service lines between the main and your property line or meter.
- Lift stations and other pumping facilities that the sewer needs to reach your site.
- Street work that comes with any of it: trenching, traffic control, pavement restoration.
- Gas lines and services in the street or easement.
Why does it surprise people?
Because the plumbing drawings usually stop at the property line and the offsite work is drawn on separate civil plans. Phoenix's water code makes the point hard to miss. A developer must furnish the water mains inside the development and in the streets around it. The developer must also build any off-site water mains needed to complete a looped connection to existing city mains, "regardless of whether the water lines will directly serve the property being developed." The code sets minimum main sizes too: 12-inch mains on section line streets, 8-inch on mid-section line streets and 6-inch on other streets, unless peak demand and fire flow call for larger. The city can also require you to replace an undersized existing main along your frontage.
### Three quick tests to sort a line
If you are not sure which side a pipe falls on, ask three questions.
- 1Is it inside the property line? If yes, it is onsite, unless it sits in a utility easement that crosses your lot. Easement rules are different, and our page on utility easement vs right-of-way for sewer repair explains why.
- 2Would the city or utility own it once it is built? Public mains, taps and lift stations usually end up city property. That points to offsite work with public standards.
- 3Does the work touch the street, sidewalk or alley? If yes, expect a right-of-way permit and traffic control on top of the plumbing permit.
Use these as planning questions, not an ownership test. A service pipe can cross a lot boundary without a maintenance boundary occurring there. Utility terms, accepted public facilities, recorded easements and permit conditions control.
Who permits offsite work, and who does it?
Engineering, utility and right-of-way review may accompany building or plumbing review. In Scottsdale, offsite sewer tap plans go to the One Stop Shop, and a Permission to Work in the Right-of-Way (PWR) permit is required for all work within rights-of-way and easements granted for public purposes. Scottsdale also requires an approved barricade and traffic control plan before construction. Ask Mesa which engineering and permit reviews apply to the proposed work.
Outside the Valley the same split shows up. Pima County describes its Site Construction Permit as an engineering document that authorizes grading, paving, sewer design and "associated off-site ROW work."
The plumbing permit and the right-of-way permit are two separate approvals for two separate scopes. If you also need to dig the street, read do you need a permit to dig in the right-of-way in Phoenix and utility easement vs right-of-way for sewer repair.
Who does the work and who owns it afterward depends on the utility, and Phoenix shows how split it can be. For a sewer tap, city crews install the tap and wye, and the contractor installs the line from the wye to the property line. For a water tap and meter, city crews install the tap from the main to the property line, and the box, meter and tap remain city property. Mains that developers build under Phoenix code become and remain the city's property once the city accepts them. Phoenix's outside-city policy adds that service connections and main extensions go in public right-of-way, and a main extension in the right-of-way needs an easement, license or non-revocable permit.
What should you do first?
Ask the utility where its line ends and yours begins for your parcel, then get a survey and utility plans that show it. Ask for a written answer on service availability before you close on land: see what a will-serve letter is. Then find out who pays for anything that has to be extended in who pays to extend a water or sewer main, and how the connection itself works in how a tap works. Our page on who is responsible for the sewer line in Phoenix covers the repair side of the same boundary.
For available customer-side plumbing work, HQ Plumbing & Air can discuss the scope: we are licensed and insured, and the estimate is free. Requirements differ by city, so confirm the ones for your address with the utility and building department before you pull anything.
For the related service-planning question, see what happens when the nearest sewer main is not at your property.
For the related service-planning question, see who builds and owns an offsite gas line extension.
For the related service-planning question, see who approves and owns an underground fire line in the valley.