What Changed in North Carolina’s Septic Rules (15A NCAC 18E)

Sourced from 15A NCAC 18E as published by the NC Office of Administrative Hearings, N.C. General Statutes Chapter 130A Article 11, and legislative directives under S.L. 2023-77, S.L. 2023-90 and S.L. 2024-49 — last checked August 2026.

Why the Rewrite Happened

The old rules, 15A NCAC 18A .1900, had been in place since 1990. Thirty-four years is a long time in any technical field, and the gap between what the code permitted and what septic technology could actually deliver had grown wide.

Rather than patch the old rules, the Division of Public Health’s On-Site Water Protection program repealed them and adopted an entirely new subchapter. Part of the stated reasoning was organizational — stakeholders had flagged that the old rules were difficult to navigate, and a clean reorganization makes future revisions easier.

The process was lengthy. The rules were adopted by the Commission for Public Health in August 2018 and approved by the Rules Review Commission in two parts that October and November. Forty-two of the ninety-nine rules then drew written objections requesting legislative review under G.S. 150B-21.3, which is why the effective date landed in 2024 rather than years earlier.

What Actually Changed for Homeowners

More approved system types. The old code recognized a limited menu of designs. The 2024 rules expanded that list and brought advanced treatment technologies — which had been operating under provisional approvals and variances — fully into the code.

This matters most in the Piedmont and the mountains, where challenging soils previously limited difficult lots to a handful of expensive engineered solutions. If your property was evaluated under the old rules and you were quoted a costly system, it is genuinely worth asking whether something less expensive now qualifies.

Updated soil evaluation. The criteria for soil morphology evaluation were refined and the classification system updated to better reflect North Carolina’s range — from Coastal Plain sands to mountain clay-loam.

Why You Will See Two Different Effective Dates

If you download 18E from one source and see “Eff. October 1, 2021” and from another see “Eff. January 1, 2024,” neither file is fake. The Commission for Public Health and the Rules Review Commission approved 18E to start in October 2021. The General Assembly stepped in before that happened.

House Bill 627, Session Law 2023-77, signed July 7, 2023, directed the Commission to implement 18E differently and to readopt its rules, setting out twenty specific directives covering applicability, improvement permits, septic tank capacity, dosing systems, maintenance, professional licensing, soil evaluation and available space. The codified rules at the Office of Administrative Hearings carry Eff. January 1, 2024 — that is the version your health department permits under today.

Each of those statutory directives sunsets only when a permanent rule consistent with it becomes effective. Until the Commission finishes readopting, the operative requirement on some points is the session law rather than the rule text. So if a contractor or a website quotes you an 18E rule, it is worth asking whether S.L. 2023-77 overrode that particular point — the health department applies the statute.

The change most likely to affect a homeowner is in .0207, which provides that an owner may obtain an IP or CA from the Local Health Department or a Notice of Intent from a professional engineer or Authorized On-Site Wastewater Evaluator. See our guide to the alternative permit routes.

Legislative directives implementing 18E have also addressed several practical points, including that an accessory dwelling unit is not treated as a separate dwelling unit when sizing a septic tank for a primary dwelling and an ADU, and that an ADU in common ownership with the primary dwelling does not require a multiparty agreement. Given how much interest there is in ADUs right now, that is worth knowing.

Where the Rules Live

The governing statute is N.C. General Statutes Chapter 130A, Article 11. The technical rules are 15A NCAC 18E, published by the Office of Administrative Hearings and by NC DHHS On-Site Water Protection.

Administration is by county Local Health Departments across all 100 counties, which is why practice varies between counties even though the rules are statewide.

What This Means Practically

If you are building or buying land, the expanded system options mean a lot that failed under the old rules may be worth re-evaluating.

If you are repairing an existing system, the same applies — the replacement you were quoted years ago may not be the only option now.

If you are working with a contractor, it is a fair question to ask which system types the current code approves for your soil conditions. A contractor still working from the pre-2024 menu is leaving options on the table.