Converting From Septic to Sewer: How the Process Works

When a sewer main reaches a street that used to be beyond it, the houses on septic face a choice, and sometimes a mandate. Converting is a plumbing job wrapped in two permit processes: one to connect to the sewer, one to properly abandon the septic system. Here is how the process runs.

What triggers a conversion

• A sewer extension. A utility or municipality extends a main past the property. Many jurisdictions require connection within a set window once sewer is available; others leave it optional until the septic system fails.
• A failing system. When a drainfield reaches end of life and sewer is available, connection often competes directly with replacement, and many health departments will not permit a new onsite system where sewer is reachable.
• Redevelopment. Additions, subdivisions, and rebuilds can trigger a connection requirement as a condition of approval.

The two permit tracks

1. The sewer connection. A connection or tap permit from the sewer utility, the physical lateral from the house to the main, and the utility's connection charges. The plumbing change itself is simple: the house line is rerouted from the tank to the new lateral.
2. Septic decommissioning. Health departments require the old system to be formally abandoned: tank pumped by a licensed hauler, then crushed and backfilled or removed, and the abandonment recorded. Our cost guide to septic tank abandonment walks the drivers.

Why the septic records matter in a sewer conversion

The as-built tells the contractor exactly where the tank and lines are before excavation starts, which shortens the job and protects the rest of the yard. The abandonment record matters even more afterward: it is the document that proves to a future buyer's inspector that the old tank was properly closed rather than left as a hazard. Pull what exists for your property through the records index or the parcel map before work begins.

Deciding when connection is optional

Where connection is not mandatory, the comparison is the utility's connection charges plus the lateral work on one side, against the remaining life of the septic system on the other. The system's recorded age and type, from the permit file, is the honest input to that decision.

Related guides

• Is My House on Septic or Sewer? How to Tell for Sure
• How Long Does a Septic System Last? Lifespan by Component
• Septic Permit Lookup by County

Know what is in the ground before you disconnect it

The recorded as-built shows where the tank and lines sit before excavation, and the permit file dates the system for the connect-or-keep decision. See what we hold for your property on the parcel map.

Find your county's septic records  Open the parcel map and design tool

Common questions

Do I have to connect when sewer reaches my street?

Depends entirely on local ordinance. Some jurisdictions mandate connection within a set window once sewer is available; others require it only at septic failure or redevelopment. Ask the sewer utility and the health department.

What happens to the old septic tank?

It must be formally decommissioned: pumped out by a licensed hauler, then crushed in place and backfilled or removed, with the abandonment documented. An abandoned-in-place tank that was never closed properly is a collapse hazard and a resale problem.

Can I keep using the septic system after sewer arrives?

Where connection is optional, yes, until the system fails. Many health departments will not permit a replacement onsite system once sewer is reachable, so failure usually becomes the connection point.

What records should exist after a conversion?

The sewer connection permit and the septic abandonment record. Keep both; the abandonment record is what satisfies a future buyer's inspector about the old tank.

Guide last reviewed 2026-09-08.