Mesa's amended plumbing code generally requires public-sewer connection. Existing lawful septic systems also have protections under City Code 8-4-10(C). Only Maricopa County Environmental Services can decide a sewer is not available, and then a private septic system meeting state and county rules is allowed. Tub, shower, bathroom sink and laundry drainage can go to a graywater system instead.
“The public sewer may be considered as not being available only when so determined by the Maricopa County Environmental Services Department (MCESD)”
- Applies to:
- Owners, builders and plumbing contractors connecting a Mesa building's drainage to the public sewer or a private system
- Official fee:
- Not stated in the plumbing code; a building sewer connection permit and sewer development fees are set separately by the city
- In force:
- 2024 International Plumbing Code with Mesa amendments (Mesa City Code 4-5-2, Ord. 5983)
- Last verified:
- October 4, 2026, against the official page
Section 701.2 of the plumbing code is the sentence that decides whether a building's drainage goes to the city sewer or a septic tank. Mesa rewrote it so that the answer is "the city sewer" unless the county says otherwise.
What does Mesa's amended 701.2 say?
Mesa's amendments to the 2024 International Plumbing Code appear in City Code 4-5-2. The amended 701.2 keeps the base rule and adds local detail:
- The requirement. Sanitary drainage from plumbing fixtures in buildings, and sanitary drainage systems from premises, "shall be connected to a public sewer."
- The fallback. Where a public sewer is not available, the drainage connects to a private sewage disposal system that complies with state or local requirements.
- The Mesa addition. Every building with plumbing fixtures and all premises with drainage piping must connect to a public sewer. The public sewer may be treated as unavailable "only when so determined by" Maricopa County Environmental Services (MCESD), acting under authority delegated by the Arizona Department of Environmental Quality and Arizona Administrative Code R18-9-A309.
- The exception. Drainage that carries only discharge from bathtubs, showers, lavatories, clothes washers and laundry trays need not connect to a public sewer or a private sewage disposal system if the piping connects to a system under IPC Chapter 13 or 14. Chapter 14 covers subsurface graywater soil absorption systems.
Mesa City Code 8-4-5 backs this up on the health side. It makes new septic tanks and cesspools unlawful except where no public sewer is available. The septic page explains that section and the rule for existing tanks.
What do the key terms mean?
- Sanitary drainage piping. The drain, waste and vent piping that carries wastewater from fixtures.
- MCESD. Maricopa County Environmental Services Department, which decides whether a public sewer is available for code purposes.
- Private sewage disposal system. A septic system permitted to state and county requirements.
- Graywater system. A system for handling drainage from tubs, showers, bathroom lavatories, clothes washers and laundry trays under IPC Chapter 13 or 14. Kitchen sinks are not on the list.
Who does this cover?
New builds, additions and other projects subject to Mesa's plumbing code, plus owners evaluating a sewer connection. City Code 8-4-10(C) separately allows an existing septic tank to continue while it meets county health standards. This general plumbing provision should not be read as an automatic order to replace every lawful existing tank. The county, not the city, is the one who decides that a sewer is unavailable, so a builder cannot self-certify.
Quick check: where does your drainage have to go?
| Situation | Where drainage goes | Basis |
|---|---|---|
| New building with fixtures, public sewer available | Public sewer | 701.2 |
| MCESD determines sewer is not available | Private system meeting state and county rules | 701.2, City Code 8-4-5(B) |
| Owner says the main is too far away | Still public sewer unless MCESD says otherwise | 701.2 |
| Only bath, shower, bathroom sink and laundry water | May go to a graywater system | 701.2 exception |
| Toilet and kitchen drainage | Public sewer or private system, never graywater | 701.2 |
What does this look like in real life?
A new home on an infill lot. A sewer main runs in the street. The plumbing plans show the building sewer tying into it. That is what 701.2 requires, and the connection needs its own permit under 8-4-8.
A rural-style parcel. The owner believes sewer is too far away. Under Mesa's wording the owner's belief does not count. MCESD has to determine that the public sewer is not available before a private system becomes the code path.
The edge case. A property with a laundry-to-landscape graywater setup. The exception lets the washer and shower drainage go to a system under Chapters 13 or 14, but the toilet and kitchen drainage still has to reach the public sewer or an approved private system.
What should you do next?
- 1Locate the nearest public sewer main and confirm whether it serves your parcel.
- 2If you believe sewer is unavailable, ask MCESD for the determination in writing before you design a septic system.
- 3Include the building sewer connection on the plumbing plans, and apply for the plumbing permit and the sewer connection permit.
- 4If you plan a graywater system, confirm it is designed under IPC Chapter 13 or 14 and gets its own review.
- 5Book the plumbing inspections through the city once the permit is issued, and keep the building sewer uncovered until it passes.
What do people get wrong?
- "Septic is my choice." In Mesa the county decides whether sewer is available, and where it is, drainage from fixtures connects to it.
- "Graywater means I skip the sewer entirely." Only the discharge from tubs, showers, lavatories, clothes washers and laundry trays qualifies, and only if it goes to a Chapter 13 or 14 system.
- "The 2024 IPC says the same everywhere." Mesa amended 701.2, and its city code is the version to use.
- "No sewer main out front means septic." The availability call belongs to MCESD.
How Do Other Valley Cities Handle It?
| Where | What applies | Source |
|---|---|---|
| Scottsdale | Scottsdale does not use one blanket rule. Its code requires connection when a public sewer is available and a trigger occurs, such as a new detached building with plumbing, a remodel of 50 percent or more of the building, or a county septic permit denial. | Scottsdale Revised Code 49-117 Verified September 29, 2026 |
| Chandler | Chandler lets a working private septic system continue after city sewer becomes available. A failed or unhealthy system must be abandoned to Maricopa County standards and the owner must connect. | Chandler City Code 51-3(F) Verified September 29, 2026 |
This page explains the rule. The official text at the source above governs.
Sewer Lines in Other Cities
- ChandlerDo you have to connect to Chandler city sewer if you have a septic tank? City Code 51-3
- ChandlerChandler sewer line responsibility: who repairs the pipe to the main
- ChandlerChandler sewer tap permit: what 51-7 and the street permit require
- GlendaleGlendale City Code 33-217: who repairs the sewer line from the building to the street
- PhoenixWho pays to extend a sewer main in Phoenix?
- PhoenixDo you need a permit to connect to or work on a public sewer in Phoenix?
More Mesa Codes and Permits
- Sewer LinesHow deep must a building sewer be in Mesa? Plumbing Code 305.4.1
- Sewer LinesCan you keep a septic tank in Mesa? City Code 8-4-5 and 8-4-10(C)
- Commercial PlumbingWhat is Mesa's Annual Facilities Permit for plumbing work? City Code 4-1-4(F)
- Commercial PlumbingCan a Mesa tenant improvement use permit-by-inspection? City Code 4-1-4(U)
- Permits and InspectionsWhat plumbing inspections does Mesa require? City Code 4-1-5 rough-in, concealment and final
- Commercial PlumbingDo you need a certificate of occupancy to open or change a Mesa business? City Code 4-1-6