Can you keep a septic tank in Mesa? City Code 8-4-5 and 8-4-10(C)

Section 8-4-5(A) starts with a prohibition. Except as the chapter provides, it is unlawful to construct or maintain within the city any privy, privy vault, septic tank, cesspool or other facility used to dispose of wastewater.

Section 8-4-5(B) is the exception. Where a public sanitary sewer is not available within the city or in any area under its jurisdiction, the building sewer must connect to a private wastewater disposal system that follows the Arizona Department of Environmental Quality and the Sanitary Code of Maricopa County. That system has to be built, maintained and operated "in a sanitary manner" at all times.

Section 8-4-10(C) covers systems that already exist. The city "strongly encourages" connecting when sewer becomes available, but people with existing septic tanks "may continue to use them as long as they function in a manner which does not violate Maricopa County health standards." When the county determines that a tank violates the standards, "the person shall connect to the public sewer system."

The plumbing code reaches the same result from the other direction. Under the Mesa amendment to IPC 701.2, only Maricopa County Environmental Services can decide that a public sewer is not available. The Mesa 701.2 page covers that section.

• Public sewer available. Mesa's plumbing code leaves this to the county's determination, not to the property owner's opinion.
• Private wastewater disposal system. A septic tank and leach field or similar system permitted under state and county rules.
• Building sewer. The pipe that carries drainage from the building out toward the public sewer or private system.
• Sewer development fee. A city fee tied to connecting to the sewer, set outside these code sections. Section 8-4-10(B)3 gives a credit toward it for monthly charges paid earlier by a customer who was billed but not connected.

Owners of homes and businesses on septic tanks, inside Mesa city limits, buyers checking what a septic tank means for a purchase, and builders whose site has no sewer. It does not decide how the county judges a tank, which is a Maricopa County question. A home in an unincorporated county island is outside these sections and follows Maricopa County rules.

A 1970s home inside Mesa city limits. The owner has a working septic tank and a sewer main now runs down the street. Nothing in Mesa's code forces the swap today, because 8-4-10(C) lets the tank stay. If the county later finds it in violation, 8-4-10(C) makes connecting mandatory.

A buyer with a failed inspection. The tank fails its transfer inspection. If the county then determines that it violates the health standards, 8-4-10(C) says the owner shall connect to the public sewer, and that connection needs a building sewer permit under 8-4-8.

The edge case. A new building on a parcel with no main nearby. The owner cannot decide alone that sewer is unavailable. The county makes that call, and only then does the private system in 8-4-5(B) apply.

1. 1Find out from the seller, the county or your own inspection whether the tank is working and permitted.
2. 2If you may need to connect, ask Mesa Development Services about the plumbing permit and sewer connection permit.
3. 3Ask the city for the current sewer development fee and connection charges before you budget, since they are set outside the code sections above.
4. 4Have the building sewer scoped and located before anyone digs. Work in the street or alley is covered by the city's right of way rules, which the right of way permit page explains.
5. 5Ask Maricopa County Environmental Services what it requires for taking the old tank out of service once the new connection passes inspection.

• "A working septic tank is illegal in Mesa." Section 8-4-10(C) lets an existing tank continue while it meets county health standards.
• "I can build a new septic tank if I prefer it." New systems are barred where a public sewer is available, and the county decides availability.
• "The city will inspect my tank." The standard is Maricopa County's, and the county makes the finding that triggers a connection.
• "Connecting to sewer is just a plumbing job." It also involves a connection permit, fees and often a right of way permit. See the valley sewer ownership guide for who owns which piece of pipe.